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linux_old1/include/linux/elevator.h

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Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
#ifndef _LINUX_ELEVATOR_H
#define _LINUX_ELEVATOR_H
[PATCH] elevator: define ioc counting mechanism None of the in-kernel primitives for handling "atomic" counting seem to be a good fit. We need something that is essentially free for incrementing/decrementing, while the read side may be more expensive as we only ever need to do that when a device is removed from the kernel. Use a per-cpu variable for maintaining a per-cpu ioc count and define a reading mechanism that just sums up the values. Signed-off-by: Jens Axboe <axboe@suse.de>
2006-07-22 21:37:43 +08:00
#include <linux/percpu.h>
[PATCH] BLOCK: Make it possible to disable the block layer [try #6] Make it possible to disable the block layer. Not all embedded devices require it, some can make do with just JFFS2, NFS, ramfs, etc - none of which require the block layer to be present. This patch does the following: (*) Introduces CONFIG_BLOCK to disable the block layer, buffering and blockdev support. (*) Adds dependencies on CONFIG_BLOCK to any configuration item that controls an item that uses the block layer. This includes: (*) Block I/O tracing. (*) Disk partition code. (*) All filesystems that are block based, eg: Ext3, ReiserFS, ISOFS. (*) The SCSI layer. As far as I can tell, even SCSI chardevs use the block layer to do scheduling. Some drivers that use SCSI facilities - such as USB storage - end up disabled indirectly from this. (*) Various block-based device drivers, such as IDE and the old CDROM drivers. (*) MTD blockdev handling and FTL. (*) JFFS - which uses set_bdev_super(), something it could avoid doing by taking a leaf out of JFFS2's book. (*) Makes most of the contents of linux/blkdev.h, linux/buffer_head.h and linux/elevator.h contingent on CONFIG_BLOCK being set. sector_div() is, however, still used in places, and so is still available. (*) Also made contingent are the contents of linux/mpage.h, linux/genhd.h and parts of linux/fs.h. (*) Makes a number of files in fs/ contingent on CONFIG_BLOCK. (*) Makes mm/bounce.c (bounce buffering) contingent on CONFIG_BLOCK. (*) set_page_dirty() doesn't call __set_page_dirty_buffers() if CONFIG_BLOCK is not enabled. (*) fs/no-block.c is created to hold out-of-line stubs and things that are required when CONFIG_BLOCK is not set: (*) Default blockdev file operations (to give error ENODEV on opening). (*) Makes some /proc changes: (*) /proc/devices does not list any blockdevs. (*) /proc/diskstats and /proc/partitions are contingent on CONFIG_BLOCK. (*) Makes some compat ioctl handling contingent on CONFIG_BLOCK. (*) If CONFIG_BLOCK is not defined, makes sys_quotactl() return -ENODEV if given command other than Q_SYNC or if a special device is specified. (*) In init/do_mounts.c, no reference is made to the blockdev routines if CONFIG_BLOCK is not defined. This does not prohibit NFS roots or JFFS2. (*) The bdflush, ioprio_set and ioprio_get syscalls can now be absent (return error ENOSYS by way of cond_syscall if so). (*) The seclvl_bd_claim() and seclvl_bd_release() security calls do nothing if CONFIG_BLOCK is not set, since they can't then happen. Signed-Off-By: David Howells <dhowells@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2006-10-01 02:45:40 +08:00
#ifdef CONFIG_BLOCK
block, cfq: move io_cq exit/release to blk-ioc.c With kmem_cache managed by blk-ioc, io_cq exit/release can be moved to blk-ioc too. The odd ->io_cq->exit/release() callbacks are replaced with elevator_ops->elevator_exit_icq_fn() with unlinking from both ioc and q, and freeing automatically handled by blk-ioc. The elevator operation only need to perform exit operation specific to the elevator - in cfq's case, exiting the cfqq's. Also, clearing of io_cq's on q detach is moved to block core and automatically performed on elevator switch and q release. Because the q io_cq points to might be freed before RCU callback for the io_cq runs, blk-ioc code should remember to which cache the io_cq needs to be freed when the io_cq is released. New field io_cq->__rcu_icq_cache is added for this purpose. As both the new field and rcu_head are used only after io_cq is released and the q/ioc_node fields aren't, they are put into unions. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-12-14 07:33:42 +08:00
struct io_cq;
[BLOCK] Get rid of request_queue_t typedef Some of the code has been gradually transitioned to using the proper struct request_queue, but there's lots left. So do a full sweet of the kernel and get rid of this typedef and replace its uses with the proper type. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-24 15:28:11 +08:00
typedef int (elevator_merge_fn) (struct request_queue *, struct request **,
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
struct bio *);
[BLOCK] Get rid of request_queue_t typedef Some of the code has been gradually transitioned to using the proper struct request_queue, but there's lots left. So do a full sweet of the kernel and get rid of this typedef and replace its uses with the proper type. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-24 15:28:11 +08:00
typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
[BLOCK] Get rid of request_queue_t typedef Some of the code has been gradually transitioned to using the proper struct request_queue, but there's lots left. So do a full sweet of the kernel and get rid of this typedef and replace its uses with the proper type. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-24 15:28:11 +08:00
typedef void (elevator_merged_fn) (struct request_queue *, struct request *, int);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
[BLOCK] Get rid of request_queue_t typedef Some of the code has been gradually transitioned to using the proper struct request_queue, but there's lots left. So do a full sweet of the kernel and get rid of this typedef and replace its uses with the proper type. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-24 15:28:11 +08:00
typedef int (elevator_allow_merge_fn) (struct request_queue *, struct request *, struct bio *);
[PATCH] cfq-iosched: don't allow sync merges across queues Currently we allow any merge, even if the io originates from different processes. This can cause really bad starvation and unfairness, if those ios happen to be synchronous (reads or direct writes). So add a allow_merge hook to the io scheduler ops, so an io scheduler can help decide whether a bio/process combination may be merged with an existing request. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2006-12-20 18:04:12 +08:00
blkio: Add io_merged stat This includes both the number of bios merged into requests belonging to this cgroup as well as the number of requests merged together. In the past, we've observed different merging behavior across upstream kernels, some by design some actual bugs. This stat helps a lot in debugging such problems when applications report decreased throughput with a new kernel version. This needed adding an extra elevator function to capture bios being merged as I did not want to pollute elevator code with blkiocg knowledge and hence needed the accounting invocation to come from CFQ. Signed-off-by: Divyesh Shah<dpshah@google.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2010-04-09 12:14:23 +08:00
typedef void (elevator_bio_merged_fn) (struct request_queue *,
struct request *, struct bio *);
[BLOCK] Get rid of request_queue_t typedef Some of the code has been gradually transitioned to using the proper struct request_queue, but there's lots left. So do a full sweet of the kernel and get rid of this typedef and replace its uses with the proper type. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-24 15:28:11 +08:00
typedef int (elevator_dispatch_fn) (struct request_queue *, int);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
[BLOCK] Get rid of request_queue_t typedef Some of the code has been gradually transitioned to using the proper struct request_queue, but there's lots left. So do a full sweet of the kernel and get rid of this typedef and replace its uses with the proper type. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-24 15:28:11 +08:00
typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
typedef int (elevator_may_queue_fn) (struct request_queue *, int);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
block, cfq: restructure io_cq creation path for io_context interface cleanup Add elevator_ops->elevator_init_icq_fn() and restructure cfq_create_cic() and rename it to ioc_create_icq(). The new function expects its caller to pass in io_context, uses elevator_type->icq_cache, handles generic init, calls the new elevator operation for elevator specific initialization, and returns pointer to created or looked up icq. This leaves cfq_icq_pool variable without any user. Removed. This prepares for io_context interface cleanup and doesn't introduce any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-12-14 07:33:42 +08:00
typedef void (elevator_init_icq_fn) (struct io_cq *);
block, cfq: move io_cq exit/release to blk-ioc.c With kmem_cache managed by blk-ioc, io_cq exit/release can be moved to blk-ioc too. The odd ->io_cq->exit/release() callbacks are replaced with elevator_ops->elevator_exit_icq_fn() with unlinking from both ioc and q, and freeing automatically handled by blk-ioc. The elevator operation only need to perform exit operation specific to the elevator - in cfq's case, exiting the cfqq's. Also, clearing of io_cq's on q detach is moved to block core and automatically performed on elevator switch and q release. Because the q io_cq points to might be freed before RCU callback for the io_cq runs, blk-ioc code should remember to which cache the io_cq needs to be freed when the io_cq is released. New field io_cq->__rcu_icq_cache is added for this purpose. As both the new field and rcu_head are used only after io_cq is released and the q/ioc_node fields aren't, they are put into unions. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-12-14 07:33:42 +08:00
typedef void (elevator_exit_icq_fn) (struct io_cq *);
block: implement bio_associate_current() IO scheduling and cgroup are tied to the issuing task via io_context and cgroup of %current. Unfortunately, there are cases where IOs need to be routed via a different task which makes scheduling and cgroup limit enforcement applied completely incorrectly. For example, all bios delayed by blk-throttle end up being issued by a delayed work item and get assigned the io_context of the worker task which happens to serve the work item and dumped to the default block cgroup. This is double confusing as bios which aren't delayed end up in the correct cgroup and makes using blk-throttle and cfq propio together impossible. Any code which punts IO issuing to another task is affected which is getting more and more common (e.g. btrfs). As both io_context and cgroup are firmly tied to task including userland visible APIs to manipulate them, it makes a lot of sense to match up tasks to bios. This patch implements bio_associate_current() which associates the specified bio with %current. The bio will record the associated ioc and blkcg at that point and block layer will use the recorded ones regardless of which task actually ends up issuing the bio. bio release puts the associated ioc and blkcg. It grabs and remembers ioc and blkcg instead of the task itself because task may already be dead by the time the bio is issued making ioc and blkcg inaccessible and those are all block layer cares about. elevator_set_req_fn() is updated such that the bio elvdata is being allocated for is available to the elevator. This doesn't update block cgroup policies yet. Further patches will implement the support. -v2: #ifdef CONFIG_BLK_CGROUP added around bio->bi_ioc dereference in rq_ioc() to fix build breakage. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Kent Overstreet <koverstreet@google.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06 05:15:27 +08:00
typedef int (elevator_set_req_fn) (struct request_queue *, struct request *,
struct bio *, gfp_t);
[BLOCK] Cleanup unused variable passing - ->init_queue() does not need the elevator passed in - ->put_request() is a hot path and need not have the queue passed in - cfq_update_io_seektime() does not need cfqd passed in Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2006-12-01 17:42:33 +08:00
typedef void (elevator_put_req_fn) (struct request *);
[BLOCK] Get rid of request_queue_t typedef Some of the code has been gradually transitioned to using the proper struct request_queue, but there's lots left. So do a full sweet of the kernel and get rid of this typedef and replace its uses with the proper type. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-24 15:28:11 +08:00
typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
elevator: make elevator_init_fn() return 0/-errno elevator_ops->elevator_init_fn() has a weird return value. It returns a void * which the caller should assign to q->elevator->elevator_data and %NULL return denotes init failure. Update such that it returns integer 0/-errno and sets elevator_data directly as necessary. This makes the interface more conventional and eases further cleanup. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06 05:14:57 +08:00
typedef int (elevator_init_fn) (struct request_queue *);
block: get rid of elevator_t typedef Just use struct elevator_queue everywhere instead. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-31 17:05:07 +08:00
typedef void (elevator_exit_fn) (struct elevator_queue *);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
struct elevator_ops
{
elevator_merge_fn *elevator_merge_fn;
elevator_merged_fn *elevator_merged_fn;
elevator_merge_req_fn *elevator_merge_req_fn;
[PATCH] cfq-iosched: don't allow sync merges across queues Currently we allow any merge, even if the io originates from different processes. This can cause really bad starvation and unfairness, if those ios happen to be synchronous (reads or direct writes). So add a allow_merge hook to the io scheduler ops, so an io scheduler can help decide whether a bio/process combination may be merged with an existing request. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2006-12-20 18:04:12 +08:00
elevator_allow_merge_fn *elevator_allow_merge_fn;
blkio: Add io_merged stat This includes both the number of bios merged into requests belonging to this cgroup as well as the number of requests merged together. In the past, we've observed different merging behavior across upstream kernels, some by design some actual bugs. This stat helps a lot in debugging such problems when applications report decreased throughput with a new kernel version. This needed adding an extra elevator function to capture bios being merged as I did not want to pollute elevator code with blkiocg knowledge and hence needed the accounting invocation to come from CFQ. Signed-off-by: Divyesh Shah<dpshah@google.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2010-04-09 12:14:23 +08:00
elevator_bio_merged_fn *elevator_bio_merged_fn;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
[PATCH] 01/05 Implement generic dispatch queue Implements generic dispatch queue which can replace all dispatch queues implemented by each iosched. This reduces code duplication, eases enforcing semantics over dispatch queue, and simplifies specific ioscheds. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Jens Axboe <axboe@suse.de>
2005-10-20 22:23:44 +08:00
elevator_dispatch_fn *elevator_dispatch_fn;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
elevator_add_req_fn *elevator_add_req_fn;
[PATCH] 01/05 Implement generic dispatch queue Implements generic dispatch queue which can replace all dispatch queues implemented by each iosched. This reduces code duplication, eases enforcing semantics over dispatch queue, and simplifies specific ioscheds. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Jens Axboe <axboe@suse.de>
2005-10-20 22:23:44 +08:00
elevator_activate_req_fn *elevator_activate_req_fn;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
elevator_deactivate_req_fn *elevator_deactivate_req_fn;
elevator_completed_req_fn *elevator_completed_req_fn;
elevator_request_list_fn *elevator_former_req_fn;
elevator_request_list_fn *elevator_latter_req_fn;
block, cfq: move icq creation and rq->elv.icq association to block core Now block layer knows everything necessary to create and associate icq's with requests. Move ioc_create_icq() to blk-ioc.c and update get_request() such that, if elevator_type->icq_size is set, requests are automatically associated with their matching icq's before elv_set_request(). io_context reference is also managed by block core on request alloc/free. * Only ioprio/cgroup changed handling remains from cfq_get_cic(). Collapsed into cfq_set_request(). * This removes queue kicking on icq allocation failure (for now). As icq allocation failure is rare and the only effect of queue kicking achieved was possibily accelerating queue processing, this change shouldn't be noticeable. There is a larger underlying problem. Unlike request allocation, icq allocation is not guaranteed to succeed eventually after retries. The number of icq is unbound and thus mempool can't be the solution either. This effectively adds allocation dependency on memory free path and thus possibility of deadlock. This usually wouldn't happen because icq allocation is not a hot path and, even when the condition triggers, it's highly unlikely that none of the writeback workers already has icq. However, this is still possible especially if elevator is being switched under high memory pressure, so we better get it fixed. Probably the only solution is just bypassing elevator and appending to dispatch queue on any elevator allocation failure. * Comment added to explain how icq's are managed and synchronized. This completes cleanup of io_context interface. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-12-14 07:33:42 +08:00
elevator_init_icq_fn *elevator_init_icq_fn; /* see iocontext.h */
elevator_exit_icq_fn *elevator_exit_icq_fn; /* ditto */
block, cfq: move io_cq exit/release to blk-ioc.c With kmem_cache managed by blk-ioc, io_cq exit/release can be moved to blk-ioc too. The odd ->io_cq->exit/release() callbacks are replaced with elevator_ops->elevator_exit_icq_fn() with unlinking from both ioc and q, and freeing automatically handled by blk-ioc. The elevator operation only need to perform exit operation specific to the elevator - in cfq's case, exiting the cfqq's. Also, clearing of io_cq's on q detach is moved to block core and automatically performed on elevator switch and q release. Because the q io_cq points to might be freed before RCU callback for the io_cq runs, blk-ioc code should remember to which cache the io_cq needs to be freed when the io_cq is released. New field io_cq->__rcu_icq_cache is added for this purpose. As both the new field and rcu_head are used only after io_cq is released and the q/ioc_node fields aren't, they are put into unions. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-12-14 07:33:42 +08:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
elevator_set_req_fn *elevator_set_req_fn;
elevator_put_req_fn *elevator_put_req_fn;
elevator_may_queue_fn *elevator_may_queue_fn;
elevator_init_fn *elevator_init_fn;
elevator_exit_fn *elevator_exit_fn;
};
#define ELV_NAME_MAX (16)
[PATCH] fix rmmod problems with elevator attributes, clean them up
2006-03-19 11:27:18 +08:00
struct elv_fs_entry {
struct attribute attr;
block: get rid of elevator_t typedef Just use struct elevator_queue everywhere instead. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-31 17:05:07 +08:00
ssize_t (*show)(struct elevator_queue *, char *);
ssize_t (*store)(struct elevator_queue *, const char *, size_t);
[PATCH] fix rmmod problems with elevator attributes, clean them up
2006-03-19 11:27:18 +08:00
};
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
/*
* identifies an elevator type, such as AS or deadline
*/
struct elevator_type
{
block, cfq: move icq cache management to block core Let elevators set ->icq_size and ->icq_align in elevator_type and elv_register() and elv_unregister() respectively create and destroy kmem_cache for icq. * elv_register() now can return failure. All callers updated. * icq caches are automatically named "ELVNAME_io_cq". * cfq_slab_setup/kill() are collapsed into cfq_init/exit(). * While at it, minor indentation change for iosched_cfq.elevator_name for consistency. This will help moving icq management to block core. This doesn't introduce any functional change. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-12-14 07:33:42 +08:00
/* managed by elevator core */
struct kmem_cache *icq_cache;
/* fields provided by elevator implementation */
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
struct elevator_ops ops;
block, cfq: move icq creation and rq->elv.icq association to block core Now block layer knows everything necessary to create and associate icq's with requests. Move ioc_create_icq() to blk-ioc.c and update get_request() such that, if elevator_type->icq_size is set, requests are automatically associated with their matching icq's before elv_set_request(). io_context reference is also managed by block core on request alloc/free. * Only ioprio/cgroup changed handling remains from cfq_get_cic(). Collapsed into cfq_set_request(). * This removes queue kicking on icq allocation failure (for now). As icq allocation failure is rare and the only effect of queue kicking achieved was possibily accelerating queue processing, this change shouldn't be noticeable. There is a larger underlying problem. Unlike request allocation, icq allocation is not guaranteed to succeed eventually after retries. The number of icq is unbound and thus mempool can't be the solution either. This effectively adds allocation dependency on memory free path and thus possibility of deadlock. This usually wouldn't happen because icq allocation is not a hot path and, even when the condition triggers, it's highly unlikely that none of the writeback workers already has icq. However, this is still possible especially if elevator is being switched under high memory pressure, so we better get it fixed. Probably the only solution is just bypassing elevator and appending to dispatch queue on any elevator allocation failure. * Comment added to explain how icq's are managed and synchronized. This completes cleanup of io_context interface. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-12-14 07:33:42 +08:00
size_t icq_size; /* see iocontext.h */
size_t icq_align; /* ditto */
[PATCH] fix rmmod problems with elevator attributes, clean them up
2006-03-19 11:27:18 +08:00
struct elv_fs_entry *elevator_attrs;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
char elevator_name[ELV_NAME_MAX];
struct module *elevator_owner;
block, cfq: move icq cache management to block core Let elevators set ->icq_size and ->icq_align in elevator_type and elv_register() and elv_unregister() respectively create and destroy kmem_cache for icq. * elv_register() now can return failure. All callers updated. * icq caches are automatically named "ELVNAME_io_cq". * cfq_slab_setup/kill() are collapsed into cfq_init/exit(). * While at it, minor indentation change for iosched_cfq.elevator_name for consistency. This will help moving icq management to block core. This doesn't introduce any functional change. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-12-14 07:33:42 +08:00
/* managed by elevator core */
char icq_cache_name[ELV_NAME_MAX + 5]; /* elvname + "_io_cq" */
block: remove elevator_queue->ops elevator_queue->ops points to the same ops struct ->elevator_type.ops is pointing to. The only effect of caching it in elevator_queue is shorter notation - it doesn't save any indirect derefence. Relocate elevator_type->list which used only during module init/exit to the end of the structure, rename elevator_queue->elevator_type to ->type, and replace elevator_queue->ops with elevator_queue->type.ops. This doesn't introduce any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-12-14 07:33:41 +08:00
struct list_head list;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
};
/*
s/assoicated/associated/ Signed-off-by: Adrian Bunk <bunk@stusta.de>
2006-01-10 07:09:36 +08:00
* each queue has an elevator_queue associated with it
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
*/
struct elevator_queue
{
block: remove elevator_queue->ops elevator_queue->ops points to the same ops struct ->elevator_type.ops is pointing to. The only effect of caching it in elevator_queue is shorter notation - it doesn't save any indirect derefence. Relocate elevator_type->list which used only during module init/exit to the end of the structure, rename elevator_queue->elevator_type to ->type, and replace elevator_queue->ops with elevator_queue->type.ops. This doesn't introduce any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-12-14 07:33:41 +08:00
struct elevator_type *type;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
void *elevator_data;
struct kobject kobj;
[PATCH] elevator_t lifetime rules and sysfs fixes
2006-03-19 07:35:43 +08:00
struct mutex sysfs_lock;
[PATCH] elevator: move the backmerging logic into the elevator core Right now, every IO scheduler implements its own backmerging (except for noop, which does no merging). That results in duplicated code for essentially the same operation, which is never a good thing. This patch moves the backmerging out of the io schedulers and into the elevator core. We save 1.6kb of text and as a bonus get backmerging for noop as well. Win-win! Signed-off-by: Jens Axboe <axboe@suse.de>
2006-07-28 15:23:08 +08:00
struct hlist_head *hash;
elevator: fix oops on early call to elevator_change() 2.6.36 introduces an API for drivers to switch the IO scheduler instead of manually calling the elevator exit and init functions. This API was added since q->elevator must be cleared in between those two calls. And since we already have this functionality directly from use by the sysfs interface to switch schedulers online, it was prudent to reuse it internally too. But this API needs the queue to be in a fully initialized state before it is called, or it will attempt to unregister elevator kobjects before they have been added. This results in an oops like this: BUG: unable to handle kernel NULL pointer dereference at 0000000000000051 IP: [<ffffffff8116f15e>] sysfs_create_dir+0x2e/0xc0 PGD 47ddfc067 PUD 47c6a1067 PMD 0 Oops: 0000 [#1] PREEMPT SMP last sysfs file: /sys/devices/pci0000:00/0000:00:02.0/0000:04:00.1/irq CPU 2 Modules linked in: t(+) loop hid_apple usbhid ahci ehci_hcd uhci_hcd libahci usbcore nls_base igb Pid: 7319, comm: modprobe Not tainted 2.6.36-rc6+ #132 QSSC-S4R/QSSC-S4R RIP: 0010:[<ffffffff8116f15e>] [<ffffffff8116f15e>] sysfs_create_dir+0x2e/0xc0 RSP: 0018:ffff88027da25d08 EFLAGS: 00010246 RAX: ffff88047c68c528 RBX: 00000000fffffffe RCX: 0000000000000000 RDX: 000000000000002f RSI: 000000000000002f RDI: ffff88047e196c88 RBP: ffff88027da25d38 R08: 0000000000000000 R09: d84156c5635688c0 R10: d84156c5635688c0 R11: 0000000000000000 R12: ffff88047e196c88 R13: 0000000000000000 R14: 0000000000000000 R15: ffff88047c68c528 FS: 00007fcb0b26f6e0(0000) GS:ffff880287400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000000000051 CR3: 000000047e76e000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process modprobe (pid: 7319, threadinfo ffff88027da24000, task ffff88027d377090) Stack: ffff88027da25d58 ffff88047c68c528 00000000fffffffe ffff88047e196c88 <0> ffff88047c68c528 ffff88047e05bd90 ffff88027da25d78 ffffffff8123fb77 <0> ffff88047e05bd90 0000000000000000 ffff88047e196c88 ffff88047c68c528 Call Trace: [<ffffffff8123fb77>] kobject_add_internal+0xe7/0x1f0 [<ffffffff8123fd98>] kobject_add_varg+0x38/0x60 [<ffffffff8123feb9>] kobject_add+0x69/0x90 [<ffffffff8116efe0>] ? sysfs_remove_dir+0x20/0xa0 [<ffffffff8103d48d>] ? sub_preempt_count+0x9d/0xe0 [<ffffffff8143de20>] ? _raw_spin_unlock+0x30/0x50 [<ffffffff8116efe0>] ? sysfs_remove_dir+0x20/0xa0 [<ffffffff8116eff4>] ? sysfs_remove_dir+0x34/0xa0 [<ffffffff81224204>] elv_register_queue+0x34/0xa0 [<ffffffff81224aad>] elevator_change+0xfd/0x250 [<ffffffffa007e000>] ? t_init+0x0/0x361 [t] [<ffffffffa007e000>] ? t_init+0x0/0x361 [t] [<ffffffffa007e0a8>] t_init+0xa8/0x361 [t] [<ffffffff810001de>] do_one_initcall+0x3e/0x170 [<ffffffff8108c3fd>] sys_init_module+0xbd/0x220 [<ffffffff81002f2b>] system_call_fastpath+0x16/0x1b Code: e5 41 56 41 55 41 54 49 89 fc 53 48 83 ec 10 48 85 ff 74 52 48 8b 47 18 49 c7 c5 00 46 61 81 48 85 c0 74 04 4c 8b 68 30 45 31 f6 <41> 80 7d 51 00 74 0e 49 8b 44 24 28 4c 89 e7 ff 50 20 49 89 c6 RIP [<ffffffff8116f15e>] sysfs_create_dir+0x2e/0xc0 RSP <ffff88027da25d08> CR2: 0000000000000051 ---[ end trace a6541d3bf07945df ]--- Fix this by adding a registered bit to the elevator queue, which is set when the sysfs kobjects have been registered. Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-10-07 15:35:16 +08:00
unsigned int registered:1;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
};
/*
* block elevator interface
*/
[BLOCK] Get rid of request_queue_t typedef Some of the code has been gradually transitioned to using the proper struct request_queue, but there's lots left. So do a full sweet of the kernel and get rid of this typedef and replace its uses with the proper type. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-24 15:28:11 +08:00
extern void elv_dispatch_sort(struct request_queue *, struct request *);
extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
block: remove per-queue plugging Code has been converted over to the new explicit on-stack plugging, and delay users have been converted to use the new API for that. So lets kill off the old plugging along with aops->sync_page(). Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-03-10 15:52:07 +08:00
extern void elv_add_request(struct request_queue *, struct request *, int);
extern void __elv_add_request(struct request_queue *, struct request *, int);
[BLOCK] Get rid of request_queue_t typedef Some of the code has been gradually transitioned to using the proper struct request_queue, but there's lots left. So do a full sweet of the kernel and get rid of this typedef and replace its uses with the proper type. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-24 15:28:11 +08:00
extern int elv_merge(struct request_queue *, struct request **, struct bio *);
extern void elv_merge_requests(struct request_queue *, struct request *,
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
struct request *);
[BLOCK] Get rid of request_queue_t typedef Some of the code has been gradually transitioned to using the proper struct request_queue, but there's lots left. So do a full sweet of the kernel and get rid of this typedef and replace its uses with the proper type. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-24 15:28:11 +08:00
extern void elv_merged_request(struct request_queue *, struct request *, int);
blkio: Add io_merged stat This includes both the number of bios merged into requests belonging to this cgroup as well as the number of requests merged together. In the past, we've observed different merging behavior across upstream kernels, some by design some actual bugs. This stat helps a lot in debugging such problems when applications report decreased throughput with a new kernel version. This needed adding an extra elevator function to capture bios being merged as I did not want to pollute elevator code with blkiocg knowledge and hence needed the accounting invocation to come from CFQ. Signed-off-by: Divyesh Shah<dpshah@google.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2010-04-09 12:14:23 +08:00
extern void elv_bio_merged(struct request_queue *q, struct request *,
struct bio *);
[BLOCK] Get rid of request_queue_t typedef Some of the code has been gradually transitioned to using the proper struct request_queue, but there's lots left. So do a full sweet of the kernel and get rid of this typedef and replace its uses with the proper type. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-24 15:28:11 +08:00
extern void elv_requeue_request(struct request_queue *, struct request *);
extern struct request *elv_former_request(struct request_queue *, struct request *);
extern struct request *elv_latter_request(struct request_queue *, struct request *);
extern int elv_register_queue(struct request_queue *q);
extern void elv_unregister_queue(struct request_queue *q);
extern int elv_may_queue(struct request_queue *, int);
block: Add interface to abort queued requests Signed-off-by: Mike Anderson <andmike@linux.vnet.ibm.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-09-14 02:31:27 +08:00
extern void elv_abort_queue(struct request_queue *);
[BLOCK] Get rid of request_queue_t typedef Some of the code has been gradually transitioned to using the proper struct request_queue, but there's lots left. So do a full sweet of the kernel and get rid of this typedef and replace its uses with the proper type. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-24 15:28:11 +08:00
extern void elv_completed_request(struct request_queue *, struct request *);
block: implement bio_associate_current() IO scheduling and cgroup are tied to the issuing task via io_context and cgroup of %current. Unfortunately, there are cases where IOs need to be routed via a different task which makes scheduling and cgroup limit enforcement applied completely incorrectly. For example, all bios delayed by blk-throttle end up being issued by a delayed work item and get assigned the io_context of the worker task which happens to serve the work item and dumped to the default block cgroup. This is double confusing as bios which aren't delayed end up in the correct cgroup and makes using blk-throttle and cfq propio together impossible. Any code which punts IO issuing to another task is affected which is getting more and more common (e.g. btrfs). As both io_context and cgroup are firmly tied to task including userland visible APIs to manipulate them, it makes a lot of sense to match up tasks to bios. This patch implements bio_associate_current() which associates the specified bio with %current. The bio will record the associated ioc and blkcg at that point and block layer will use the recorded ones regardless of which task actually ends up issuing the bio. bio release puts the associated ioc and blkcg. It grabs and remembers ioc and blkcg instead of the task itself because task may already be dead by the time the bio is issued making ioc and blkcg inaccessible and those are all block layer cares about. elevator_set_req_fn() is updated such that the bio elvdata is being allocated for is available to the elevator. This doesn't update block cgroup policies yet. Further patches will implement the support. -v2: #ifdef CONFIG_BLK_CGROUP added around bio->bi_ioc dereference in rq_ioc() to fix build breakage. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Kent Overstreet <koverstreet@google.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06 05:15:27 +08:00
extern int elv_set_request(struct request_queue *q, struct request *rq,
struct bio *bio, gfp_t gfp_mask);
[BLOCK] Get rid of request_queue_t typedef Some of the code has been gradually transitioned to using the proper struct request_queue, but there's lots left. So do a full sweet of the kernel and get rid of this typedef and replace its uses with the proper type. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-24 15:28:11 +08:00
extern void elv_put_request(struct request_queue *, struct request *);
block: fix inconsistency in I/O stat accounting code This forces in_flight to be zero when turning off or on the I/O stat accounting and stops updating I/O stats in attempt_merge() when accounting is turned off. Signed-off-by: Jerome Marchand <jmarchan@redhat.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-03-27 17:31:51 +08:00
extern void elv_drain_elevator(struct request_queue *);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
/*
* io scheduler registration
*/
block, cfq: move icq cache management to block core Let elevators set ->icq_size and ->icq_align in elevator_type and elv_register() and elv_unregister() respectively create and destroy kmem_cache for icq. * elv_register() now can return failure. All callers updated. * icq caches are automatically named "ELVNAME_io_cq". * cfq_slab_setup/kill() are collapsed into cfq_init/exit(). * While at it, minor indentation change for iosched_cfq.elevator_name for consistency. This will help moving icq management to block core. This doesn't introduce any functional change. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-12-14 07:33:42 +08:00
extern int elv_register(struct elevator_type *);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
extern void elv_unregister(struct elevator_type *);
/*
* io scheduler sysfs switching
*/
[BLOCK] Get rid of request_queue_t typedef Some of the code has been gradually transitioned to using the proper struct request_queue, but there's lots left. So do a full sweet of the kernel and get rid of this typedef and replace its uses with the proper type. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-24 15:28:11 +08:00
extern ssize_t elv_iosched_show(struct request_queue *, char *);
extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
[BLOCK] Get rid of request_queue_t typedef Some of the code has been gradually transitioned to using the proper struct request_queue, but there's lots left. So do a full sweet of the kernel and get rid of this typedef and replace its uses with the proper type. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-24 15:28:11 +08:00
extern int elevator_init(struct request_queue *, char *);
block: get rid of elevator_t typedef Just use struct elevator_queue everywhere instead. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-31 17:05:07 +08:00
extern void elevator_exit(struct elevator_queue *);
block: add function call to switch the IO scheduler from a driver Currently drivers must do an elevator_exit() + elevator_init() to switch IO schedulers. There are a few problems with this: - Since commit 1abec4fdbb142e3ccb6ce99832fae42129134a96, elevator_init() requires a zeroed out q->elevator pointer. The two existing in-kernel users don't do that. - It will only work at initialization time, since using the above two-staged construct does not properly quisce the queue. So add elevator_change() which takes care of this, and convert the elv_iosched_store() sysfs interface to use this helper as well. Reported-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com> Reported-by: Kevin Vigor <kevin@vigor.nu> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-08-23 19:52:19 +08:00
extern int elevator_change(struct request_queue *, const char *);
block: separate out blk_rq_merge_ok() and blk_try_merge() from elevator functions blk_rq_merge_ok() is the elevator-neutral part of merge eligibility test. blk_try_merge() determines merge direction and expects the caller to have tested elv_rq_merge_ok() previously. elv_rq_merge_ok() now wraps blk_rq_merge_ok() and then calls elv_iosched_allow_merge(). elv_try_merge() is removed and the two callers are updated to call elv_rq_merge_ok() explicitly followed by blk_try_merge(). While at it, make rq_merge_ok() functions return bool. This is to prepare for plug merge update and doesn't introduce any behavior change. This is based on Jens' patch to skip elevator_allow_merge_fn() from plug merge. Signed-off-by: Tejun Heo <tj@kernel.org> LKML-Reference: <4F16F3CA.90904@kernel.dk> Original-patch-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-02-08 16:19:38 +08:00
extern bool elv_rq_merge_ok(struct request *, struct bio *);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
[PATCH] elevator: abstract out the rbtree sort handling The rbtree sort/lookup/reposition logic is mostly duplicated in cfq/deadline/as, so move it to the elevator core. The io schedulers still provide the actual rb root, as we don't want to impose any sort of specific handling on the schedulers. Introduce the helpers and rb_node in struct request to help migrate the IO schedulers. Signed-off-by: Jens Axboe <axboe@suse.de>
2006-07-13 17:55:04 +08:00
/*
* Helper functions.
*/
[BLOCK] Get rid of request_queue_t typedef Some of the code has been gradually transitioned to using the proper struct request_queue, but there's lots left. So do a full sweet of the kernel and get rid of this typedef and replace its uses with the proper type. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-24 15:28:11 +08:00
extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
[PATCH] elevator: abstract out the rbtree sort handling The rbtree sort/lookup/reposition logic is mostly duplicated in cfq/deadline/as, so move it to the elevator core. The io schedulers still provide the actual rb root, as we don't want to impose any sort of specific handling on the schedulers. Introduce the helpers and rb_node in struct request to help migrate the IO schedulers. Signed-off-by: Jens Axboe <axboe@suse.de>
2006-07-13 17:55:04 +08:00
/*
* rb support functions.
*/
iosched: prevent aliased requests from starving other I/O Hi, Jens, If you recall, I posted an RFC patch for this back in July of last year: http://lkml.org/lkml/2010/7/13/279 The basic problem is that a process can issue a never-ending stream of async direct I/Os to the same sector on a device, thus starving out other I/O in the system (due to the way the alias handling works in both cfq and deadline). The solution I proposed back then was to start dispatching from the fifo after a certain number of aliases had been dispatched. Vivek asked why we had to treat aliases differently at all, and I never had a good answer. So, I put together a simple patch which allows aliases to be added to the rb tree (it adds them to the right, though that doesn't matter as the order isn't guaranteed anyway). I think this is the preferred solution, as it doesn't break up time slices in CFQ or batches in deadline. I've tested it, and it does solve the starvation issue. Let me know what you think. Cheers, Jeff Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-06-03 03:19:05 +08:00
extern void elv_rb_add(struct rb_root *, struct request *);
[PATCH] elevator: abstract out the rbtree sort handling The rbtree sort/lookup/reposition logic is mostly duplicated in cfq/deadline/as, so move it to the elevator core. The io schedulers still provide the actual rb root, as we don't want to impose any sort of specific handling on the schedulers. Introduce the helpers and rb_node in struct request to help migrate the IO schedulers. Signed-off-by: Jens Axboe <axboe@suse.de>
2006-07-13 17:55:04 +08:00
extern void elv_rb_del(struct rb_root *, struct request *);
extern struct request *elv_rb_find(struct rb_root *, sector_t);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
/*
* Return values from elevator merger
*/
#define ELEVATOR_NO_MERGE 0
#define ELEVATOR_FRONT_MERGE 1
#define ELEVATOR_BACK_MERGE 2
/*
* Insertion selection
*/
#define ELEVATOR_INSERT_FRONT 1
#define ELEVATOR_INSERT_BACK 2
#define ELEVATOR_INSERT_SORT 3
[BLOCK] reimplement handling of barrier request Reimplement handling of barrier requests. * Flexible handling to deal with various capabilities of target devices. * Retry support for falling back. * Tagged queues which don't support ordered tag can do ordered. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Jens Axboe <axboe@suse.de>
2006-01-06 16:51:03 +08:00
#define ELEVATOR_INSERT_REQUEUE 4
block: reimplement FLUSH/FUA to support merge The current FLUSH/FUA support has evolved from the implementation which had to perform queue draining. As such, sequencing is done queue-wide one flush request after another. However, with the draining requirement gone, there's no reason to keep the queue-wide sequential approach. This patch reimplements FLUSH/FUA support such that each FLUSH/FUA request is sequenced individually. The actual FLUSH execution is double buffered and whenever a request wants to execute one for either PRE or POSTFLUSH, it queues on the pending queue. Once certain conditions are met, a flush request is issued and on its completion all pending requests proceed to the next sequence. This allows arbitrary merging of different type of flushes. How they are merged can be primarily controlled and tuned by adjusting the above said 'conditions' used to determine when to issue the next flush. This is inspired by Darrick's patches to merge multiple zero-data flushes which helps workloads with highly concurrent fsync requests. * As flush requests are never put on the IO scheduler, request fields used for flush share space with rq->rb_node. rq->completion_data is moved out of the union. This increases the request size by one pointer. As rq->elevator_private* are used only by the iosched too, it is possible to reduce the request size further. However, to do that, we need to modify request allocation path such that iosched data is not allocated for flush requests. * FLUSH/FUA processing happens on insertion now instead of dispatch. - Comments updated as per Vivek and Mike. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: "Darrick J. Wong" <djwong@us.ibm.com> Cc: Shaohua Li <shli@kernel.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-01-25 19:43:54 +08:00
#define ELEVATOR_INSERT_FLUSH 5
block: attempt to merge with existing requests on plug flush One of the disadvantages of on-stack plugging is that we potentially lose out on merging since all pending IO isn't always visible to everybody. When we flush the on-stack plugs, right now we don't do any checks to see if potential merge candidates could be utilized. Correct this by adding a new insert variant, ELEVATOR_INSERT_SORT_MERGE. It works just ELEVATOR_INSERT_SORT, but first checks whether we can merge with an existing request before doing the insertion (if we fail merging). This fixes a regression with multiple processes issuing IO that can be merged. Thanks to Shaohua Li <shaohua.li@intel.com> for testing and fixing an accounting bug. Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-03-21 17:14:27 +08:00
#define ELEVATOR_INSERT_SORT_MERGE 6
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
/*
* return values from elevator_may_queue_fn
*/
enum {
ELV_MQUEUE_MAY,
ELV_MQUEUE_NO,
ELV_MQUEUE_MUST,
};
block: drop request->hard_* and *nr_sectors struct request has had a few different ways to represent some properties of a request. ->hard_* represent block layer's view of the request progress (completion cursor) and the ones without the prefix are supposed to represent the issue cursor and allowed to be updated as necessary by the low level drivers. The thing is that as block layer supports partial completion, the two cursors really aren't necessary and only cause confusion. In addition, manual management of request detail from low level drivers is cumbersome and error-prone at the very least. Another interesting duplicate fields are rq->[hard_]nr_sectors and rq->{hard_cur|current}_nr_sectors against rq->data_len and rq->bio->bi_size. This is more convoluted than the hard_ case. rq->[hard_]nr_sectors are initialized for requests with bio but blk_rq_bytes() uses it only for !pc requests. rq->data_len is initialized for all request but blk_rq_bytes() uses it only for pc requests. This causes good amount of confusion throughout block layer and its drivers and determining the request length has been a bit of black magic which may or may not work depending on circumstances and what the specific LLD is actually doing. rq->{hard_cur|current}_nr_sectors represent the number of sectors in the contiguous data area at the front. This is mainly used by drivers which transfers data by walking request segment-by-segment. This value always equals rq->bio->bi_size >> 9. However, data length for pc requests may not be multiple of 512 bytes and using this field becomes a bit confusing. In general, having multiple fields to represent the same property leads only to confusion and subtle bugs. With recent block low level driver cleanups, no driver is accessing or manipulating these duplicate fields directly. Drop all the duplicates. Now rq->sector means the current sector, rq->data_len the current total length and rq->bio->bi_size the current segment length. Everything else is defined in terms of these three and available only through accessors. * blk_recalc_rq_sectors() is collapsed into blk_update_request() and now handles pc and fs requests equally other than rq->sector update. This means that now pc requests can use partial completion too (no in-kernel user yet tho). * bio_cur_sectors() is replaced with bio_cur_bytes() as block layer now uses byte count as the primary data length. * blk_rq_pos() is now guranteed to be always correct. In-block users converted. * blk_rq_bytes() is now guaranteed to be always valid as is blk_rq_sectors(). In-block users converted. * blk_rq_sectors() is now guaranteed to equal blk_rq_bytes() >> 9. More convenient one is used. * blk_rq_bytes() and blk_rq_cur_bytes() are now inlined and take const pointer to request. [ Impact: API cleanup, single way to represent one property of a request ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-05-07 21:24:41 +08:00
#define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
[PATCH] elevator: abstract out the rbtree sort handling The rbtree sort/lookup/reposition logic is mostly duplicated in cfq/deadline/as, so move it to the elevator core. The io schedulers still provide the actual rb root, as we don't want to impose any sort of specific handling on the schedulers. Introduce the helpers and rb_node in struct request to help migrate the IO schedulers. Signed-off-by: Jens Axboe <axboe@suse.de>
2006-07-13 17:55:04 +08:00
#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
[PATCH] generic dispatch fixes - Split elv_dispatch_insert() into two functions - Rename rq_last_sector() to rq_end_sector() Signed-off-by: Jens Axboe <axboe@suse.de>
2005-10-20 22:37:00 +08:00
[PATCH] elevator: introduce a way to reuse rq for internal FIFO handling The io schedulers can use this instead of having to allocate space for it themselves. Signed-off-by: Jens Axboe <axboe@suse.de>
2006-07-12 03:49:15 +08:00
/*
block: add support for IO CPU affinity This patch adds support for controlling the IO completion CPU of either all requests on a queue, or on a per-request basis. We export a sysfs variable (rq_affinity) which, if set, migrates completions of requests to the CPU that originally submitted it. A bio helper (bio_set_completion_cpu()) is also added, so that queuers can ask for completion on that specific CPU. In testing, this has been show to cut the system time by as much as 20-40% on synthetic workloads where CPU affinity is desired. This requires a little help from the architecture, so it'll only work as designed for archs that are using the new generic smp helper infrastructure. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-09-14 02:26:01 +08:00
* Hack to reuse the csd.list list_head as the fifo time holder while
[PATCH] elevator: introduce a way to reuse rq for internal FIFO handling The io schedulers can use this instead of having to allocate space for it themselves. Signed-off-by: Jens Axboe <axboe@suse.de>
2006-07-12 03:49:15 +08:00
* the request is in the io scheduler. Saves an unsigned long in rq.
*/
block: add support for IO CPU affinity This patch adds support for controlling the IO completion CPU of either all requests on a queue, or on a per-request basis. We export a sysfs variable (rq_affinity) which, if set, migrates completions of requests to the CPU that originally submitted it. A bio helper (bio_set_completion_cpu()) is also added, so that queuers can ask for completion on that specific CPU. In testing, this has been show to cut the system time by as much as 20-40% on synthetic workloads where CPU affinity is desired. This requires a little help from the architecture, so it'll only work as designed for archs that are using the new generic smp helper infrastructure. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-09-14 02:26:01 +08:00
#define rq_fifo_time(rq) ((unsigned long) (rq)->csd.list.next)
#define rq_set_fifo_time(rq,exp) ((rq)->csd.list.next = (void *) (exp))
[PATCH] elevator: introduce a way to reuse rq for internal FIFO handling The io schedulers can use this instead of having to allocate space for it themselves. Signed-off-by: Jens Axboe <axboe@suse.de>
2006-07-12 03:49:15 +08:00
#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
#define rq_fifo_clear(rq) do { \
list_del_init(&(rq)->queuelist); \
block: add support for IO CPU affinity This patch adds support for controlling the IO completion CPU of either all requests on a queue, or on a per-request basis. We export a sysfs variable (rq_affinity) which, if set, migrates completions of requests to the CPU that originally submitted it. A bio helper (bio_set_completion_cpu()) is also added, so that queuers can ask for completion on that specific CPU. In testing, this has been show to cut the system time by as much as 20-40% on synthetic workloads where CPU affinity is desired. This requires a little help from the architecture, so it'll only work as designed for archs that are using the new generic smp helper infrastructure. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-09-14 02:26:01 +08:00
INIT_LIST_HEAD(&(rq)->csd.list); \
[PATCH] elevator: introduce a way to reuse rq for internal FIFO handling The io schedulers can use this instead of having to allocate space for it themselves. Signed-off-by: Jens Axboe <axboe@suse.de>
2006-07-12 03:49:15 +08:00
} while (0)
[PATCH] BLOCK: Make it possible to disable the block layer [try #6] Make it possible to disable the block layer. Not all embedded devices require it, some can make do with just JFFS2, NFS, ramfs, etc - none of which require the block layer to be present. This patch does the following: (*) Introduces CONFIG_BLOCK to disable the block layer, buffering and blockdev support. (*) Adds dependencies on CONFIG_BLOCK to any configuration item that controls an item that uses the block layer. This includes: (*) Block I/O tracing. (*) Disk partition code. (*) All filesystems that are block based, eg: Ext3, ReiserFS, ISOFS. (*) The SCSI layer. As far as I can tell, even SCSI chardevs use the block layer to do scheduling. Some drivers that use SCSI facilities - such as USB storage - end up disabled indirectly from this. (*) Various block-based device drivers, such as IDE and the old CDROM drivers. (*) MTD blockdev handling and FTL. (*) JFFS - which uses set_bdev_super(), something it could avoid doing by taking a leaf out of JFFS2's book. (*) Makes most of the contents of linux/blkdev.h, linux/buffer_head.h and linux/elevator.h contingent on CONFIG_BLOCK being set. sector_div() is, however, still used in places, and so is still available. (*) Also made contingent are the contents of linux/mpage.h, linux/genhd.h and parts of linux/fs.h. (*) Makes a number of files in fs/ contingent on CONFIG_BLOCK. (*) Makes mm/bounce.c (bounce buffering) contingent on CONFIG_BLOCK. (*) set_page_dirty() doesn't call __set_page_dirty_buffers() if CONFIG_BLOCK is not enabled. (*) fs/no-block.c is created to hold out-of-line stubs and things that are required when CONFIG_BLOCK is not set: (*) Default blockdev file operations (to give error ENODEV on opening). (*) Makes some /proc changes: (*) /proc/devices does not list any blockdevs. (*) /proc/diskstats and /proc/partitions are contingent on CONFIG_BLOCK. (*) Makes some compat ioctl handling contingent on CONFIG_BLOCK. (*) If CONFIG_BLOCK is not defined, makes sys_quotactl() return -ENODEV if given command other than Q_SYNC or if a special device is specified. (*) In init/do_mounts.c, no reference is made to the blockdev routines if CONFIG_BLOCK is not defined. This does not prohibit NFS roots or JFFS2. (*) The bdflush, ioprio_set and ioprio_get syscalls can now be absent (return error ENOSYS by way of cond_syscall if so). (*) The seclvl_bd_claim() and seclvl_bd_release() security calls do nothing if CONFIG_BLOCK is not set, since they can't then happen. Signed-Off-By: David Howells <dhowells@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2006-10-01 02:45:40 +08:00
#endif /* CONFIG_BLOCK */
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
#endif