linux/block/blk-cgroup.h

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#ifndef _BLK_CGROUP_H
#define _BLK_CGROUP_H
/*
* Common Block IO controller cgroup interface
*
* Based on ideas and code from CFQ, CFS and BFQ:
* Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
*
* Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
* Paolo Valente <paolo.valente@unimore.it>
*
* Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
* Nauman Rafique <nauman@google.com>
*/
#include <linux/cgroup.h>
#include <linux/u64_stats_sync.h>
enum blkio_policy_id {
BLKIO_POLICY_PROP = 0, /* Proportional Bandwidth division */
BLKIO_POLICY_THROTL, /* Throttling */
BLKIO_NR_POLICIES,
};
/* Max limits for throttle policy */
#define THROTL_IOPS_MAX UINT_MAX
#ifdef CONFIG_BLK_CGROUP
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enum stat_type {
/* Total time spent (in ns) between request dispatch to the driver and
* request completion for IOs doen by this cgroup. This may not be
* accurate when NCQ is turned on. */
BLKIO_STAT_SERVICE_TIME = 0,
/* Total time spent waiting in scheduler queue in ns */
BLKIO_STAT_WAIT_TIME,
/* Number of IOs queued up */
BLKIO_STAT_QUEUED,
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/* All the single valued stats go below this */
BLKIO_STAT_TIME,
#ifdef CONFIG_DEBUG_BLK_CGROUP
/* Time not charged to this cgroup */
BLKIO_STAT_UNACCOUNTED_TIME,
BLKIO_STAT_AVG_QUEUE_SIZE,
blkio: Add more debug-only per-cgroup stats 1) group_wait_time - This is the amount of time the cgroup had to wait to get a timeslice for one of its queues from when it became busy, i.e., went from 0 to 1 request queued. This is different from the io_wait_time which is the cumulative total of the amount of time spent by each IO in that cgroup waiting in the scheduler queue. This stat is a great way to find out any jobs in the fleet that are being starved or waiting for longer than what is expected (due to an IO controller bug or any other issue). 2) empty_time - This is the amount of time a cgroup spends w/o any pending requests. This stat is useful when a job does not seem to be able to use its assigned disk share by helping check if that is happening due to an IO controller bug or because the job is not submitting enough IOs. 3) idle_time - This is the amount of time spent by the IO scheduler idling for a given cgroup in anticipation of a better request than the exising ones from other queues/cgroups. All these stats are recorded using start and stop events. When reading these stats, we do not add the delta between the current time and the last start time if we're between the start and stop events. We avoid doing this to make sure that these numbers are always monotonically increasing when read. Since we're using sched_clock() which may use the tsc as its source, it may induce some inconsistency (due to tsc resync across cpus) if we included the current delta. Signed-off-by: Divyesh Shah<dpshah@google.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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BLKIO_STAT_IDLE_TIME,
BLKIO_STAT_EMPTY_TIME,
BLKIO_STAT_GROUP_WAIT_TIME,
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BLKIO_STAT_DEQUEUE
#endif
};
/* Per cpu stats */
enum stat_type_cpu {
BLKIO_STAT_CPU_SECTORS,
/* Total bytes transferred */
BLKIO_STAT_CPU_SERVICE_BYTES,
/* Total IOs serviced, post merge */
BLKIO_STAT_CPU_SERVICED,
/* Number of IOs merged */
BLKIO_STAT_CPU_MERGED,
BLKIO_STAT_CPU_NR
};
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enum stat_sub_type {
BLKIO_STAT_READ = 0,
BLKIO_STAT_WRITE,
BLKIO_STAT_SYNC,
BLKIO_STAT_ASYNC,
BLKIO_STAT_TOTAL
};
blkio: Add more debug-only per-cgroup stats 1) group_wait_time - This is the amount of time the cgroup had to wait to get a timeslice for one of its queues from when it became busy, i.e., went from 0 to 1 request queued. This is different from the io_wait_time which is the cumulative total of the amount of time spent by each IO in that cgroup waiting in the scheduler queue. This stat is a great way to find out any jobs in the fleet that are being starved or waiting for longer than what is expected (due to an IO controller bug or any other issue). 2) empty_time - This is the amount of time a cgroup spends w/o any pending requests. This stat is useful when a job does not seem to be able to use its assigned disk share by helping check if that is happening due to an IO controller bug or because the job is not submitting enough IOs. 3) idle_time - This is the amount of time spent by the IO scheduler idling for a given cgroup in anticipation of a better request than the exising ones from other queues/cgroups. All these stats are recorded using start and stop events. When reading these stats, we do not add the delta between the current time and the last start time if we're between the start and stop events. We avoid doing this to make sure that these numbers are always monotonically increasing when read. Since we're using sched_clock() which may use the tsc as its source, it may induce some inconsistency (due to tsc resync across cpus) if we included the current delta. Signed-off-by: Divyesh Shah<dpshah@google.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2010-04-09 12:15:35 +08:00
/* blkg state flags */
enum blkg_state_flags {
BLKG_waiting = 0,
BLKG_idling,
BLKG_empty,
};
/* cgroup files owned by proportional weight policy */
enum blkcg_file_name_prop {
BLKIO_PROP_weight = 1,
BLKIO_PROP_weight_device,
BLKIO_PROP_io_service_bytes,
BLKIO_PROP_io_serviced,
BLKIO_PROP_time,
BLKIO_PROP_sectors,
BLKIO_PROP_unaccounted_time,
BLKIO_PROP_io_service_time,
BLKIO_PROP_io_wait_time,
BLKIO_PROP_io_merged,
BLKIO_PROP_io_queued,
BLKIO_PROP_avg_queue_size,
BLKIO_PROP_group_wait_time,
BLKIO_PROP_idle_time,
BLKIO_PROP_empty_time,
BLKIO_PROP_dequeue,
};
/* cgroup files owned by throttle policy */
enum blkcg_file_name_throtl {
BLKIO_THROTL_read_bps_device,
BLKIO_THROTL_write_bps_device,
BLKIO_THROTL_read_iops_device,
BLKIO_THROTL_write_iops_device,
BLKIO_THROTL_io_service_bytes,
BLKIO_THROTL_io_serviced,
};
struct blkio_cgroup {
struct cgroup_subsys_state css;
unsigned int weight;
spinlock_t lock;
struct hlist_head blkg_list;
};
struct blkio_group_stats {
/* total disk time and nr sectors dispatched by this group */
uint64_t time;
uint64_t stat_arr[BLKIO_STAT_QUEUED + 1][BLKIO_STAT_TOTAL];
#ifdef CONFIG_DEBUG_BLK_CGROUP
/* Time not charged to this cgroup */
uint64_t unaccounted_time;
/* Sum of number of IOs queued across all samples */
uint64_t avg_queue_size_sum;
/* Count of samples taken for average */
uint64_t avg_queue_size_samples;
/* How many times this group has been removed from service tree */
unsigned long dequeue;
blkio: Add more debug-only per-cgroup stats 1) group_wait_time - This is the amount of time the cgroup had to wait to get a timeslice for one of its queues from when it became busy, i.e., went from 0 to 1 request queued. This is different from the io_wait_time which is the cumulative total of the amount of time spent by each IO in that cgroup waiting in the scheduler queue. This stat is a great way to find out any jobs in the fleet that are being starved or waiting for longer than what is expected (due to an IO controller bug or any other issue). 2) empty_time - This is the amount of time a cgroup spends w/o any pending requests. This stat is useful when a job does not seem to be able to use its assigned disk share by helping check if that is happening due to an IO controller bug or because the job is not submitting enough IOs. 3) idle_time - This is the amount of time spent by the IO scheduler idling for a given cgroup in anticipation of a better request than the exising ones from other queues/cgroups. All these stats are recorded using start and stop events. When reading these stats, we do not add the delta between the current time and the last start time if we're between the start and stop events. We avoid doing this to make sure that these numbers are always monotonically increasing when read. Since we're using sched_clock() which may use the tsc as its source, it may induce some inconsistency (due to tsc resync across cpus) if we included the current delta. Signed-off-by: Divyesh Shah<dpshah@google.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2010-04-09 12:15:35 +08:00
/* Total time spent waiting for it to be assigned a timeslice. */
uint64_t group_wait_time;
uint64_t start_group_wait_time;
/* Time spent idling for this blkio_group */
uint64_t idle_time;
uint64_t start_idle_time;
/*
* Total time when we have requests queued and do not contain the
* current active queue.
*/
uint64_t empty_time;
uint64_t start_empty_time;
uint16_t flags;
#endif
};
/* Per cpu blkio group stats */
struct blkio_group_stats_cpu {
uint64_t sectors;
uint64_t stat_arr_cpu[BLKIO_STAT_CPU_NR][BLKIO_STAT_TOTAL];
struct u64_stats_sync syncp;
};
blkcg: don't allow or retain configuration of missing devices blkcg is very peculiar in that it allows setting and remembering configurations for non-existent devices by maintaining separate data structures for configuration. This behavior is completely out of the usual norms and outright confusing; furthermore, it uses dev_t number to match the configuration to devices, which is unpredictable to begin with and becomes completely unuseable if EXT_DEVT is fully used. It is wholely unnecessary - we already have fully functional userland mechanism to program devices being hotplugged which has full access to device identification, connection topology and filesystem information. Add a new struct blkio_group_conf which contains all blkcg configurations to blkio_group and let blkio_group, which can be created iff the associated device exists and is removed when the associated device goes away, carry all configurations. Note that, after this patch, all newly created blkg's will always have the default configuration (unlimited for throttling and blkcg's weight for propio). This patch makes blkio_policy_node meaningless but doesn't remove it. The next patch will. -v2: Updated to retry after short sleep if blkg lookup/creation failed due to the queue being temporarily bypassed as indicated by -EBUSY return. Pointed out by Vivek. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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struct blkio_group_conf {
unsigned int weight;
unsigned int iops[2];
u64 bps[2];
};
/* per-blkg per-policy data */
struct blkg_policy_data {
/* the blkg this per-policy data belongs to */
struct blkio_group *blkg;
/* pol->pdata_size bytes of private data used by policy impl */
char pdata[] __aligned(__alignof__(unsigned long long));
};
struct blkio_group {
/* Pointer to the associated request_queue, RCU protected */
struct request_queue __rcu *q;
struct hlist_node blkcg_node;
struct blkio_cgroup *blkcg;
/* Store cgroup path */
char path[128];
/* policy which owns this blk group */
enum blkio_policy_id plid;
blkcg: don't allow or retain configuration of missing devices blkcg is very peculiar in that it allows setting and remembering configurations for non-existent devices by maintaining separate data structures for configuration. This behavior is completely out of the usual norms and outright confusing; furthermore, it uses dev_t number to match the configuration to devices, which is unpredictable to begin with and becomes completely unuseable if EXT_DEVT is fully used. It is wholely unnecessary - we already have fully functional userland mechanism to program devices being hotplugged which has full access to device identification, connection topology and filesystem information. Add a new struct blkio_group_conf which contains all blkcg configurations to blkio_group and let blkio_group, which can be created iff the associated device exists and is removed when the associated device goes away, carry all configurations. Note that, after this patch, all newly created blkg's will always have the default configuration (unlimited for throttling and blkcg's weight for propio). This patch makes blkio_policy_node meaningless but doesn't remove it. The next patch will. -v2: Updated to retry after short sleep if blkg lookup/creation failed due to the queue being temporarily bypassed as indicated by -EBUSY return. Pointed out by Vivek. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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/* Configuration */
struct blkio_group_conf conf;
/* Need to serialize the stats in the case of reset/update */
spinlock_t stats_lock;
struct blkio_group_stats stats;
/* Per cpu stats pointer */
struct blkio_group_stats_cpu __percpu *stats_cpu;
struct blkg_policy_data *pd;
};
typedef void (blkio_init_group_fn)(struct blkio_group *blkg);
blkcg: factor out blkio_group creation Currently both blk-throttle and cfq-iosched implement their own blkio_group creation code in throtl_get_tg() and cfq_get_cfqg(). This patch factors out the common code into blkg_lookup_create(), which returns ERR_PTR value so that transitional failures due to queue bypass can be distinguished from other failures. * New plkio_policy_ops methods blkio_alloc_group_fn() and blkio_link_group_fn added. Both are transitional and will be removed once the blkg management code is fully moved into blk-cgroup.c. * blkio_alloc_group_fn() allocates policy-specific blkg which is usually a larger data structure with blkg as the first entry and intiailizes it. Note that initialization of blkg proper, including percpu stats, is responsibility of blk-cgroup proper. Note that default config (weight, bps...) initialization is done from this method; otherwise, we end up violating locking order between blkcg and q locks via blkcg_get_CONF() functions. * blkio_link_group_fn() is called under queue_lock and responsible for linking the blkg to the queue. blkcg side is handled by blk-cgroup proper. * The common blkg creation function is named blkg_lookup_create() and blkiocg_lookup_group() is renamed to blkg_lookup() for consistency. Also, throtl / cfq related functions are similarly [re]named for consistency. This simplifies blkcg policy implementations and enables further cleanup. -v2: Vivek noticed that blkg_lookup_create() incorrectly tested blk_queue_dead() instead of blk_queue_bypass() leading a user of the function ending up creating a new blkg on bypassing queue. This is a bug introduced while relocating bypass patches before this one. Fixed. -v3: ERR_PTR patch folded into this one. @for_root added to blkg_lookup_create() to allow creating root group on a bypassed queue during elevator switch. 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 05:15:06 +08:00
typedef void (blkio_link_group_fn)(struct request_queue *q,
struct blkio_group *blkg);
typedef void (blkio_unlink_group_fn)(struct request_queue *q,
struct blkio_group *blkg);
blkcg: shoot down blkio_groups on elevator switch Elevator switch may involve changes to blkcg policies. Implement shoot down of blkio_groups. Combined with the previous bypass updates, the end goal is updating blkcg core such that it can ensure that blkcg's being affected become quiescent and don't have any per-blkg data hanging around before commencing any policy updates. Until queues are made aware of the policies that applies to them, as an interim step, all per-policy blkg data will be shot down. * blk-throtl doesn't need this change as it can't be disabled for a live queue; however, update it anyway as the scheduled blkg unification requires this behavior change. This means that blk-throtl configuration will be unnecessarily lost over elevator switch. This oddity will be removed after blkcg learns to associate individual policies with request_queues. * blk-throtl dosen't shoot down root_tg. This is to ease transition. Unified blkg will always have persistent root group and not shooting down root_tg for now eases transition to that point by avoiding having to update td->root_tg and is safe as blk-throtl can never be disabled -v2: Vivek pointed out that group list is not guaranteed to be empty on return from clear function if it raced cgroup removal and lost. Fix it by waiting a bit and retrying. This kludge will soon be removed once locking is updated such that blkg is never in limbo state between blkcg and request_queue locks. blk-throtl no longer shoots down root_tg to avoid breaking td->root_tg. Also, Nest queue_lock inside blkio_list_lock not the other way around to avoid introduce possible deadlock via blkcg lock. -v3: blkcg_clear_queue() repositioned and renamed to blkg_destroy_all() to increase consistency with later changes. cfq_clear_queue() updated to check q->elevator before dereferencing it to avoid NULL dereference on not fully initialized queues (used by later change). 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 05:15:00 +08:00
typedef bool (blkio_clear_queue_fn)(struct request_queue *q);
typedef void (blkio_update_group_weight_fn)(struct request_queue *q,
struct blkio_group *blkg, unsigned int weight);
typedef void (blkio_update_group_read_bps_fn)(struct request_queue *q,
struct blkio_group *blkg, u64 read_bps);
typedef void (blkio_update_group_write_bps_fn)(struct request_queue *q,
struct blkio_group *blkg, u64 write_bps);
typedef void (blkio_update_group_read_iops_fn)(struct request_queue *q,
struct blkio_group *blkg, unsigned int read_iops);
typedef void (blkio_update_group_write_iops_fn)(struct request_queue *q,
struct blkio_group *blkg, unsigned int write_iops);
struct blkio_policy_ops {
blkio_init_group_fn *blkio_init_group_fn;
blkcg: factor out blkio_group creation Currently both blk-throttle and cfq-iosched implement their own blkio_group creation code in throtl_get_tg() and cfq_get_cfqg(). This patch factors out the common code into blkg_lookup_create(), which returns ERR_PTR value so that transitional failures due to queue bypass can be distinguished from other failures. * New plkio_policy_ops methods blkio_alloc_group_fn() and blkio_link_group_fn added. Both are transitional and will be removed once the blkg management code is fully moved into blk-cgroup.c. * blkio_alloc_group_fn() allocates policy-specific blkg which is usually a larger data structure with blkg as the first entry and intiailizes it. Note that initialization of blkg proper, including percpu stats, is responsibility of blk-cgroup proper. Note that default config (weight, bps...) initialization is done from this method; otherwise, we end up violating locking order between blkcg and q locks via blkcg_get_CONF() functions. * blkio_link_group_fn() is called under queue_lock and responsible for linking the blkg to the queue. blkcg side is handled by blk-cgroup proper. * The common blkg creation function is named blkg_lookup_create() and blkiocg_lookup_group() is renamed to blkg_lookup() for consistency. Also, throtl / cfq related functions are similarly [re]named for consistency. This simplifies blkcg policy implementations and enables further cleanup. -v2: Vivek noticed that blkg_lookup_create() incorrectly tested blk_queue_dead() instead of blk_queue_bypass() leading a user of the function ending up creating a new blkg on bypassing queue. This is a bug introduced while relocating bypass patches before this one. Fixed. -v3: ERR_PTR patch folded into this one. @for_root added to blkg_lookup_create() to allow creating root group on a bypassed queue during elevator switch. 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 05:15:06 +08:00
blkio_link_group_fn *blkio_link_group_fn;
blkio_unlink_group_fn *blkio_unlink_group_fn;
blkcg: shoot down blkio_groups on elevator switch Elevator switch may involve changes to blkcg policies. Implement shoot down of blkio_groups. Combined with the previous bypass updates, the end goal is updating blkcg core such that it can ensure that blkcg's being affected become quiescent and don't have any per-blkg data hanging around before commencing any policy updates. Until queues are made aware of the policies that applies to them, as an interim step, all per-policy blkg data will be shot down. * blk-throtl doesn't need this change as it can't be disabled for a live queue; however, update it anyway as the scheduled blkg unification requires this behavior change. This means that blk-throtl configuration will be unnecessarily lost over elevator switch. This oddity will be removed after blkcg learns to associate individual policies with request_queues. * blk-throtl dosen't shoot down root_tg. This is to ease transition. Unified blkg will always have persistent root group and not shooting down root_tg for now eases transition to that point by avoiding having to update td->root_tg and is safe as blk-throtl can never be disabled -v2: Vivek pointed out that group list is not guaranteed to be empty on return from clear function if it raced cgroup removal and lost. Fix it by waiting a bit and retrying. This kludge will soon be removed once locking is updated such that blkg is never in limbo state between blkcg and request_queue locks. blk-throtl no longer shoots down root_tg to avoid breaking td->root_tg. Also, Nest queue_lock inside blkio_list_lock not the other way around to avoid introduce possible deadlock via blkcg lock. -v3: blkcg_clear_queue() repositioned and renamed to blkg_destroy_all() to increase consistency with later changes. cfq_clear_queue() updated to check q->elevator before dereferencing it to avoid NULL dereference on not fully initialized queues (used by later change). 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 05:15:00 +08:00
blkio_clear_queue_fn *blkio_clear_queue_fn;
blkio_update_group_weight_fn *blkio_update_group_weight_fn;
blkio_update_group_read_bps_fn *blkio_update_group_read_bps_fn;
blkio_update_group_write_bps_fn *blkio_update_group_write_bps_fn;
blkio_update_group_read_iops_fn *blkio_update_group_read_iops_fn;
blkio_update_group_write_iops_fn *blkio_update_group_write_iops_fn;
};
struct blkio_policy_type {
struct list_head list;
struct blkio_policy_ops ops;
enum blkio_policy_id plid;
size_t pdata_size; /* policy specific private data size */
};
extern int blkcg_init_queue(struct request_queue *q);
extern void blkcg_drain_queue(struct request_queue *q);
extern void blkcg_exit_queue(struct request_queue *q);
/* Blkio controller policy registration */
extern void blkio_policy_register(struct blkio_policy_type *);
extern void blkio_policy_unregister(struct blkio_policy_type *);
blkcg: shoot down blkio_groups on elevator switch Elevator switch may involve changes to blkcg policies. Implement shoot down of blkio_groups. Combined with the previous bypass updates, the end goal is updating blkcg core such that it can ensure that blkcg's being affected become quiescent and don't have any per-blkg data hanging around before commencing any policy updates. Until queues are made aware of the policies that applies to them, as an interim step, all per-policy blkg data will be shot down. * blk-throtl doesn't need this change as it can't be disabled for a live queue; however, update it anyway as the scheduled blkg unification requires this behavior change. This means that blk-throtl configuration will be unnecessarily lost over elevator switch. This oddity will be removed after blkcg learns to associate individual policies with request_queues. * blk-throtl dosen't shoot down root_tg. This is to ease transition. Unified blkg will always have persistent root group and not shooting down root_tg for now eases transition to that point by avoiding having to update td->root_tg and is safe as blk-throtl can never be disabled -v2: Vivek pointed out that group list is not guaranteed to be empty on return from clear function if it raced cgroup removal and lost. Fix it by waiting a bit and retrying. This kludge will soon be removed once locking is updated such that blkg is never in limbo state between blkcg and request_queue locks. blk-throtl no longer shoots down root_tg to avoid breaking td->root_tg. Also, Nest queue_lock inside blkio_list_lock not the other way around to avoid introduce possible deadlock via blkcg lock. -v3: blkcg_clear_queue() repositioned and renamed to blkg_destroy_all() to increase consistency with later changes. cfq_clear_queue() updated to check q->elevator before dereferencing it to avoid NULL dereference on not fully initialized queues (used by later change). 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 05:15:00 +08:00
extern void blkg_destroy_all(struct request_queue *q);
/**
* blkg_to_pdata - get policy private data
* @blkg: blkg of interest
* @pol: policy of interest
*
* Return pointer to private data associated with the @blkg-@pol pair.
*/
static inline void *blkg_to_pdata(struct blkio_group *blkg,
struct blkio_policy_type *pol)
{
return blkg ? blkg->pd->pdata : NULL;
}
/**
* pdata_to_blkg - get blkg associated with policy private data
* @pdata: policy private data of interest
* @pol: policy @pdata is for
*
* @pdata is policy private data for @pol. Determine the blkg it's
* associated with.
*/
static inline struct blkio_group *pdata_to_blkg(void *pdata,
struct blkio_policy_type *pol)
{
if (pdata) {
struct blkg_policy_data *pd =
container_of(pdata, struct blkg_policy_data, pdata);
return pd->blkg;
}
return NULL;
}
static inline char *blkg_path(struct blkio_group *blkg)
{
return blkg->path;
}
#else
struct blkio_group {
};
struct blkio_policy_type {
};
static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
static inline void blkcg_drain_queue(struct request_queue *q) { }
static inline void blkcg_exit_queue(struct request_queue *q) { }
static inline void blkio_policy_register(struct blkio_policy_type *blkiop) { }
static inline void blkio_policy_unregister(struct blkio_policy_type *blkiop) { }
blkcg: shoot down blkio_groups on elevator switch Elevator switch may involve changes to blkcg policies. Implement shoot down of blkio_groups. Combined with the previous bypass updates, the end goal is updating blkcg core such that it can ensure that blkcg's being affected become quiescent and don't have any per-blkg data hanging around before commencing any policy updates. Until queues are made aware of the policies that applies to them, as an interim step, all per-policy blkg data will be shot down. * blk-throtl doesn't need this change as it can't be disabled for a live queue; however, update it anyway as the scheduled blkg unification requires this behavior change. This means that blk-throtl configuration will be unnecessarily lost over elevator switch. This oddity will be removed after blkcg learns to associate individual policies with request_queues. * blk-throtl dosen't shoot down root_tg. This is to ease transition. Unified blkg will always have persistent root group and not shooting down root_tg for now eases transition to that point by avoiding having to update td->root_tg and is safe as blk-throtl can never be disabled -v2: Vivek pointed out that group list is not guaranteed to be empty on return from clear function if it raced cgroup removal and lost. Fix it by waiting a bit and retrying. This kludge will soon be removed once locking is updated such that blkg is never in limbo state between blkcg and request_queue locks. blk-throtl no longer shoots down root_tg to avoid breaking td->root_tg. Also, Nest queue_lock inside blkio_list_lock not the other way around to avoid introduce possible deadlock via blkcg lock. -v3: blkcg_clear_queue() repositioned and renamed to blkg_destroy_all() to increase consistency with later changes. cfq_clear_queue() updated to check q->elevator before dereferencing it to avoid NULL dereference on not fully initialized queues (used by later change). 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 05:15:00 +08:00
static inline void blkg_destroy_all(struct request_queue *q) { }
static inline void *blkg_to_pdata(struct blkio_group *blkg,
struct blkio_policy_type *pol) { return NULL; }
static inline struct blkio_group *pdata_to_blkg(void *pdata,
struct blkio_policy_type *pol) { return NULL; }
static inline char *blkg_path(struct blkio_group *blkg) { return NULL; }
#endif
#define BLKIO_WEIGHT_MIN 10
#define BLKIO_WEIGHT_MAX 1000
#define BLKIO_WEIGHT_DEFAULT 500
#ifdef CONFIG_DEBUG_BLK_CGROUP
void blkiocg_update_avg_queue_size_stats(struct blkio_group *blkg);
void blkiocg_update_dequeue_stats(struct blkio_group *blkg,
unsigned long dequeue);
blkio: Add more debug-only per-cgroup stats 1) group_wait_time - This is the amount of time the cgroup had to wait to get a timeslice for one of its queues from when it became busy, i.e., went from 0 to 1 request queued. This is different from the io_wait_time which is the cumulative total of the amount of time spent by each IO in that cgroup waiting in the scheduler queue. This stat is a great way to find out any jobs in the fleet that are being starved or waiting for longer than what is expected (due to an IO controller bug or any other issue). 2) empty_time - This is the amount of time a cgroup spends w/o any pending requests. This stat is useful when a job does not seem to be able to use its assigned disk share by helping check if that is happening due to an IO controller bug or because the job is not submitting enough IOs. 3) idle_time - This is the amount of time spent by the IO scheduler idling for a given cgroup in anticipation of a better request than the exising ones from other queues/cgroups. All these stats are recorded using start and stop events. When reading these stats, we do not add the delta between the current time and the last start time if we're between the start and stop events. We avoid doing this to make sure that these numbers are always monotonically increasing when read. Since we're using sched_clock() which may use the tsc as its source, it may induce some inconsistency (due to tsc resync across cpus) if we included the current delta. Signed-off-by: Divyesh Shah<dpshah@google.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2010-04-09 12:15:35 +08:00
void blkiocg_update_set_idle_time_stats(struct blkio_group *blkg);
void blkiocg_update_idle_time_stats(struct blkio_group *blkg);
blkio: Fix another BUG_ON() crash due to cfqq movement across groups o Once in a while, I was hitting a BUG_ON() in blkio code. empty_time was assuming that upon slice expiry, group can't be marked empty already (except forced dispatch). But this assumption is broken if cfqq can move (group_isolation=0) across groups after receiving a request. I think most likely in this case we got a request in a cfqq and accounted the rq in one group, later while adding the cfqq to tree, we moved the queue to a different group which was already marked empty and after dispatch from slice we found group already marked empty and raised alarm. This patch does not error out if group is already marked empty. This can introduce some empty_time stat error only in case of group_isolation=0. This is better than crashing. In case of group_isolation=1 we should still get same stats as before this patch. [ 222.308546] ------------[ cut here ]------------ [ 222.309311] kernel BUG at block/blk-cgroup.c:236! [ 222.309311] invalid opcode: 0000 [#1] SMP [ 222.309311] last sysfs file: /sys/devices/virtual/block/dm-3/queue/scheduler [ 222.309311] CPU 1 [ 222.309311] Modules linked in: dm_round_robin dm_multipath qla2xxx scsi_transport_fc dm_zero dm_mirror dm_region_hash dm_log dm_mod [last unloaded: scsi_wait_scan] [ 222.309311] [ 222.309311] Pid: 4780, comm: fio Not tainted 2.6.34-rc4-blkio-config #68 0A98h/HP xw8600 Workstation [ 222.309311] RIP: 0010:[<ffffffff8121ad88>] [<ffffffff8121ad88>] blkiocg_set_start_empty_time+0x50/0x83 [ 222.309311] RSP: 0018:ffff8800ba6e79f8 EFLAGS: 00010002 [ 222.309311] RAX: 0000000000000082 RBX: ffff8800a13b7990 RCX: ffff8800a13b7808 [ 222.309311] RDX: 0000000000002121 RSI: 0000000000000082 RDI: ffff8800a13b7a30 [ 222.309311] RBP: ffff8800ba6e7a18 R08: 0000000000000000 R09: 0000000000000001 [ 222.309311] R10: 000000000002f8c8 R11: ffff8800ba6e7ad8 R12: ffff8800a13b78ff [ 222.309311] R13: ffff8800a13b7990 R14: 0000000000000001 R15: ffff8800a13b7808 [ 222.309311] FS: 00007f3beec476f0(0000) GS:ffff880001e40000(0000) knlGS:0000000000000000 [ 222.309311] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 222.309311] CR2: 000000000040e7f0 CR3: 00000000a12d5000 CR4: 00000000000006e0 [ 222.309311] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 222.309311] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 222.309311] Process fio (pid: 4780, threadinfo ffff8800ba6e6000, task ffff8800b3d6bf00) [ 222.309311] Stack: [ 222.309311] 0000000000000001 ffff8800bab17a48 ffff8800bab17a48 ffff8800a13b7800 [ 222.309311] <0> ffff8800ba6e7a68 ffffffff8121da35 ffff880000000001 00ff8800ba5c5698 [ 222.309311] <0> ffff8800ba6e7a68 ffff8800a13b7800 0000000000000000 ffff8800bab17a48 [ 222.309311] Call Trace: [ 222.309311] [<ffffffff8121da35>] __cfq_slice_expired+0x2af/0x3ec [ 222.309311] [<ffffffff8121fd7b>] cfq_dispatch_requests+0x2c8/0x8e8 [ 222.309311] [<ffffffff8120f1cd>] ? spin_unlock_irqrestore+0xe/0x10 [ 222.309311] [<ffffffff8120fb1a>] ? blk_insert_cloned_request+0x70/0x7b [ 222.309311] [<ffffffff81210461>] blk_peek_request+0x191/0x1a7 [ 222.309311] [<ffffffffa0002799>] dm_request_fn+0x38/0x14c [dm_mod] [ 222.309311] [<ffffffff810ae61f>] ? sync_page_killable+0x0/0x35 [ 222.309311] [<ffffffff81210fd4>] __generic_unplug_device+0x32/0x37 [ 222.309311] [<ffffffff81211274>] generic_unplug_device+0x2e/0x3c [ 222.309311] [<ffffffffa00011a6>] dm_unplug_all+0x42/0x5b [dm_mod] [ 222.309311] [<ffffffff8120ca37>] blk_unplug+0x29/0x2d [ 222.309311] [<ffffffff8120ca4d>] blk_backing_dev_unplug+0x12/0x14 [ 222.309311] [<ffffffff81109a7a>] block_sync_page+0x35/0x39 [ 222.309311] [<ffffffff810ae616>] sync_page+0x41/0x4a [ 222.309311] [<ffffffff810ae62d>] sync_page_killable+0xe/0x35 [ 222.309311] [<ffffffff8158aa59>] __wait_on_bit_lock+0x46/0x8f [ 222.309311] [<ffffffff810ae4f5>] __lock_page_killable+0x66/0x6d [ 222.309311] [<ffffffff81056f9c>] ? wake_bit_function+0x0/0x33 [ 222.309311] [<ffffffff810ae528>] lock_page_killable+0x2c/0x2e [ 222.309311] [<ffffffff810afbc5>] generic_file_aio_read+0x361/0x4f0 [ 222.309311] [<ffffffff810ea044>] do_sync_read+0xcb/0x108 [ 222.309311] [<ffffffff811e42f7>] ? security_file_permission+0x16/0x18 [ 222.309311] [<ffffffff810ea6ab>] vfs_read+0xab/0x108 [ 222.309311] [<ffffffff810ea7c8>] sys_read+0x4a/0x6e [ 222.309311] [<ffffffff81002b5b>] system_call_fastpath+0x16/0x1b [ 222.309311] Code: 58 01 00 00 00 48 89 c6 75 0a 48 83 bb 60 01 00 00 00 74 09 48 8d bb a0 00 00 00 eb 35 41 fe cc 74 0d f6 83 c0 01 00 00 04 74 04 <0f> 0b eb fe 48 89 75 e8 e8 be e0 de ff 66 83 8b c0 01 00 00 04 [ 222.309311] RIP [<ffffffff8121ad88>] blkiocg_set_start_empty_time+0x50/0x83 [ 222.309311] RSP <ffff8800ba6e79f8> [ 222.309311] ---[ end trace 32b4f71dffc15712 ]--- Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Divyesh Shah <dpshah@google.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2010-04-27 01:25:11 +08:00
void blkiocg_set_start_empty_time(struct blkio_group *blkg);
blkio: Add more debug-only per-cgroup stats 1) group_wait_time - This is the amount of time the cgroup had to wait to get a timeslice for one of its queues from when it became busy, i.e., went from 0 to 1 request queued. This is different from the io_wait_time which is the cumulative total of the amount of time spent by each IO in that cgroup waiting in the scheduler queue. This stat is a great way to find out any jobs in the fleet that are being starved or waiting for longer than what is expected (due to an IO controller bug or any other issue). 2) empty_time - This is the amount of time a cgroup spends w/o any pending requests. This stat is useful when a job does not seem to be able to use its assigned disk share by helping check if that is happening due to an IO controller bug or because the job is not submitting enough IOs. 3) idle_time - This is the amount of time spent by the IO scheduler idling for a given cgroup in anticipation of a better request than the exising ones from other queues/cgroups. All these stats are recorded using start and stop events. When reading these stats, we do not add the delta between the current time and the last start time if we're between the start and stop events. We avoid doing this to make sure that these numbers are always monotonically increasing when read. Since we're using sched_clock() which may use the tsc as its source, it may induce some inconsistency (due to tsc resync across cpus) if we included the current delta. Signed-off-by: Divyesh Shah<dpshah@google.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2010-04-09 12:15:35 +08:00
#define BLKG_FLAG_FNS(name) \
static inline void blkio_mark_blkg_##name( \
struct blkio_group_stats *stats) \
{ \
stats->flags |= (1 << BLKG_##name); \
} \
static inline void blkio_clear_blkg_##name( \
struct blkio_group_stats *stats) \
{ \
stats->flags &= ~(1 << BLKG_##name); \
} \
static inline int blkio_blkg_##name(struct blkio_group_stats *stats) \
{ \
return (stats->flags & (1 << BLKG_##name)) != 0; \
} \
BLKG_FLAG_FNS(waiting)
BLKG_FLAG_FNS(idling)
BLKG_FLAG_FNS(empty)
#undef BLKG_FLAG_FNS
#else
static inline void blkiocg_update_avg_queue_size_stats(
struct blkio_group *blkg) {}
static inline void blkiocg_update_dequeue_stats(struct blkio_group *blkg,
unsigned long dequeue) {}
blkio: Add more debug-only per-cgroup stats 1) group_wait_time - This is the amount of time the cgroup had to wait to get a timeslice for one of its queues from when it became busy, i.e., went from 0 to 1 request queued. This is different from the io_wait_time which is the cumulative total of the amount of time spent by each IO in that cgroup waiting in the scheduler queue. This stat is a great way to find out any jobs in the fleet that are being starved or waiting for longer than what is expected (due to an IO controller bug or any other issue). 2) empty_time - This is the amount of time a cgroup spends w/o any pending requests. This stat is useful when a job does not seem to be able to use its assigned disk share by helping check if that is happening due to an IO controller bug or because the job is not submitting enough IOs. 3) idle_time - This is the amount of time spent by the IO scheduler idling for a given cgroup in anticipation of a better request than the exising ones from other queues/cgroups. All these stats are recorded using start and stop events. When reading these stats, we do not add the delta between the current time and the last start time if we're between the start and stop events. We avoid doing this to make sure that these numbers are always monotonically increasing when read. Since we're using sched_clock() which may use the tsc as its source, it may induce some inconsistency (due to tsc resync across cpus) if we included the current delta. Signed-off-by: Divyesh Shah<dpshah@google.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2010-04-09 12:15:35 +08:00
static inline void blkiocg_update_set_idle_time_stats(struct blkio_group *blkg)
{}
static inline void blkiocg_update_idle_time_stats(struct blkio_group *blkg) {}
blkio: Fix another BUG_ON() crash due to cfqq movement across groups o Once in a while, I was hitting a BUG_ON() in blkio code. empty_time was assuming that upon slice expiry, group can't be marked empty already (except forced dispatch). But this assumption is broken if cfqq can move (group_isolation=0) across groups after receiving a request. I think most likely in this case we got a request in a cfqq and accounted the rq in one group, later while adding the cfqq to tree, we moved the queue to a different group which was already marked empty and after dispatch from slice we found group already marked empty and raised alarm. This patch does not error out if group is already marked empty. This can introduce some empty_time stat error only in case of group_isolation=0. This is better than crashing. In case of group_isolation=1 we should still get same stats as before this patch. [ 222.308546] ------------[ cut here ]------------ [ 222.309311] kernel BUG at block/blk-cgroup.c:236! [ 222.309311] invalid opcode: 0000 [#1] SMP [ 222.309311] last sysfs file: /sys/devices/virtual/block/dm-3/queue/scheduler [ 222.309311] CPU 1 [ 222.309311] Modules linked in: dm_round_robin dm_multipath qla2xxx scsi_transport_fc dm_zero dm_mirror dm_region_hash dm_log dm_mod [last unloaded: scsi_wait_scan] [ 222.309311] [ 222.309311] Pid: 4780, comm: fio Not tainted 2.6.34-rc4-blkio-config #68 0A98h/HP xw8600 Workstation [ 222.309311] RIP: 0010:[<ffffffff8121ad88>] [<ffffffff8121ad88>] blkiocg_set_start_empty_time+0x50/0x83 [ 222.309311] RSP: 0018:ffff8800ba6e79f8 EFLAGS: 00010002 [ 222.309311] RAX: 0000000000000082 RBX: ffff8800a13b7990 RCX: ffff8800a13b7808 [ 222.309311] RDX: 0000000000002121 RSI: 0000000000000082 RDI: ffff8800a13b7a30 [ 222.309311] RBP: ffff8800ba6e7a18 R08: 0000000000000000 R09: 0000000000000001 [ 222.309311] R10: 000000000002f8c8 R11: ffff8800ba6e7ad8 R12: ffff8800a13b78ff [ 222.309311] R13: ffff8800a13b7990 R14: 0000000000000001 R15: ffff8800a13b7808 [ 222.309311] FS: 00007f3beec476f0(0000) GS:ffff880001e40000(0000) knlGS:0000000000000000 [ 222.309311] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 222.309311] CR2: 000000000040e7f0 CR3: 00000000a12d5000 CR4: 00000000000006e0 [ 222.309311] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 222.309311] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 222.309311] Process fio (pid: 4780, threadinfo ffff8800ba6e6000, task ffff8800b3d6bf00) [ 222.309311] Stack: [ 222.309311] 0000000000000001 ffff8800bab17a48 ffff8800bab17a48 ffff8800a13b7800 [ 222.309311] <0> ffff8800ba6e7a68 ffffffff8121da35 ffff880000000001 00ff8800ba5c5698 [ 222.309311] <0> ffff8800ba6e7a68 ffff8800a13b7800 0000000000000000 ffff8800bab17a48 [ 222.309311] Call Trace: [ 222.309311] [<ffffffff8121da35>] __cfq_slice_expired+0x2af/0x3ec [ 222.309311] [<ffffffff8121fd7b>] cfq_dispatch_requests+0x2c8/0x8e8 [ 222.309311] [<ffffffff8120f1cd>] ? spin_unlock_irqrestore+0xe/0x10 [ 222.309311] [<ffffffff8120fb1a>] ? blk_insert_cloned_request+0x70/0x7b [ 222.309311] [<ffffffff81210461>] blk_peek_request+0x191/0x1a7 [ 222.309311] [<ffffffffa0002799>] dm_request_fn+0x38/0x14c [dm_mod] [ 222.309311] [<ffffffff810ae61f>] ? sync_page_killable+0x0/0x35 [ 222.309311] [<ffffffff81210fd4>] __generic_unplug_device+0x32/0x37 [ 222.309311] [<ffffffff81211274>] generic_unplug_device+0x2e/0x3c [ 222.309311] [<ffffffffa00011a6>] dm_unplug_all+0x42/0x5b [dm_mod] [ 222.309311] [<ffffffff8120ca37>] blk_unplug+0x29/0x2d [ 222.309311] [<ffffffff8120ca4d>] blk_backing_dev_unplug+0x12/0x14 [ 222.309311] [<ffffffff81109a7a>] block_sync_page+0x35/0x39 [ 222.309311] [<ffffffff810ae616>] sync_page+0x41/0x4a [ 222.309311] [<ffffffff810ae62d>] sync_page_killable+0xe/0x35 [ 222.309311] [<ffffffff8158aa59>] __wait_on_bit_lock+0x46/0x8f [ 222.309311] [<ffffffff810ae4f5>] __lock_page_killable+0x66/0x6d [ 222.309311] [<ffffffff81056f9c>] ? wake_bit_function+0x0/0x33 [ 222.309311] [<ffffffff810ae528>] lock_page_killable+0x2c/0x2e [ 222.309311] [<ffffffff810afbc5>] generic_file_aio_read+0x361/0x4f0 [ 222.309311] [<ffffffff810ea044>] do_sync_read+0xcb/0x108 [ 222.309311] [<ffffffff811e42f7>] ? security_file_permission+0x16/0x18 [ 222.309311] [<ffffffff810ea6ab>] vfs_read+0xab/0x108 [ 222.309311] [<ffffffff810ea7c8>] sys_read+0x4a/0x6e [ 222.309311] [<ffffffff81002b5b>] system_call_fastpath+0x16/0x1b [ 222.309311] Code: 58 01 00 00 00 48 89 c6 75 0a 48 83 bb 60 01 00 00 00 74 09 48 8d bb a0 00 00 00 eb 35 41 fe cc 74 0d f6 83 c0 01 00 00 04 74 04 <0f> 0b eb fe 48 89 75 e8 e8 be e0 de ff 66 83 8b c0 01 00 00 04 [ 222.309311] RIP [<ffffffff8121ad88>] blkiocg_set_start_empty_time+0x50/0x83 [ 222.309311] RSP <ffff8800ba6e79f8> [ 222.309311] ---[ end trace 32b4f71dffc15712 ]--- Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Divyesh Shah <dpshah@google.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2010-04-27 01:25:11 +08:00
static inline void blkiocg_set_start_empty_time(struct blkio_group *blkg) {}
#endif
#ifdef CONFIG_BLK_CGROUP
extern struct blkio_cgroup blkio_root_cgroup;
extern struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup);
extern struct blkio_cgroup *task_blkio_cgroup(struct task_struct *tsk);
extern int blkiocg_del_blkio_group(struct blkio_group *blkg);
blkcg: factor out blkio_group creation Currently both blk-throttle and cfq-iosched implement their own blkio_group creation code in throtl_get_tg() and cfq_get_cfqg(). This patch factors out the common code into blkg_lookup_create(), which returns ERR_PTR value so that transitional failures due to queue bypass can be distinguished from other failures. * New plkio_policy_ops methods blkio_alloc_group_fn() and blkio_link_group_fn added. Both are transitional and will be removed once the blkg management code is fully moved into blk-cgroup.c. * blkio_alloc_group_fn() allocates policy-specific blkg which is usually a larger data structure with blkg as the first entry and intiailizes it. Note that initialization of blkg proper, including percpu stats, is responsibility of blk-cgroup proper. Note that default config (weight, bps...) initialization is done from this method; otherwise, we end up violating locking order between blkcg and q locks via blkcg_get_CONF() functions. * blkio_link_group_fn() is called under queue_lock and responsible for linking the blkg to the queue. blkcg side is handled by blk-cgroup proper. * The common blkg creation function is named blkg_lookup_create() and blkiocg_lookup_group() is renamed to blkg_lookup() for consistency. Also, throtl / cfq related functions are similarly [re]named for consistency. This simplifies blkcg policy implementations and enables further cleanup. -v2: Vivek noticed that blkg_lookup_create() incorrectly tested blk_queue_dead() instead of blk_queue_bypass() leading a user of the function ending up creating a new blkg on bypassing queue. This is a bug introduced while relocating bypass patches before this one. Fixed. -v3: ERR_PTR patch folded into this one. @for_root added to blkg_lookup_create() to allow creating root group on a bypassed queue during elevator switch. 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 05:15:06 +08:00
extern struct blkio_group *blkg_lookup(struct blkio_cgroup *blkcg,
struct request_queue *q,
enum blkio_policy_id plid);
struct blkio_group *blkg_lookup_create(struct blkio_cgroup *blkcg,
struct request_queue *q,
enum blkio_policy_id plid,
bool for_root);
void blkiocg_update_timeslice_used(struct blkio_group *blkg,
unsigned long time,
unsigned long unaccounted_time);
2010-04-09 14:31:19 +08:00
void blkiocg_update_dispatch_stats(struct blkio_group *blkg, uint64_t bytes,
bool direction, bool sync);
void blkiocg_update_completion_stats(struct blkio_group *blkg,
uint64_t start_time, uint64_t io_start_time, bool direction, bool sync);
void blkiocg_update_io_merged_stats(struct blkio_group *blkg, bool direction,
bool sync);
void blkiocg_update_io_add_stats(struct blkio_group *blkg,
struct blkio_group *curr_blkg, bool direction, bool sync);
void blkiocg_update_io_remove_stats(struct blkio_group *blkg,
bool direction, bool sync);
#else
struct cgroup;
static inline struct blkio_cgroup *
cgroup_to_blkio_cgroup(struct cgroup *cgroup) { return NULL; }
static inline struct blkio_cgroup *
task_blkio_cgroup(struct task_struct *tsk) { return NULL; }
static inline int
blkiocg_del_blkio_group(struct blkio_group *blkg) { return 0; }
blkcg: factor out blkio_group creation Currently both blk-throttle and cfq-iosched implement their own blkio_group creation code in throtl_get_tg() and cfq_get_cfqg(). This patch factors out the common code into blkg_lookup_create(), which returns ERR_PTR value so that transitional failures due to queue bypass can be distinguished from other failures. * New plkio_policy_ops methods blkio_alloc_group_fn() and blkio_link_group_fn added. Both are transitional and will be removed once the blkg management code is fully moved into blk-cgroup.c. * blkio_alloc_group_fn() allocates policy-specific blkg which is usually a larger data structure with blkg as the first entry and intiailizes it. Note that initialization of blkg proper, including percpu stats, is responsibility of blk-cgroup proper. Note that default config (weight, bps...) initialization is done from this method; otherwise, we end up violating locking order between blkcg and q locks via blkcg_get_CONF() functions. * blkio_link_group_fn() is called under queue_lock and responsible for linking the blkg to the queue. blkcg side is handled by blk-cgroup proper. * The common blkg creation function is named blkg_lookup_create() and blkiocg_lookup_group() is renamed to blkg_lookup() for consistency. Also, throtl / cfq related functions are similarly [re]named for consistency. This simplifies blkcg policy implementations and enables further cleanup. -v2: Vivek noticed that blkg_lookup_create() incorrectly tested blk_queue_dead() instead of blk_queue_bypass() leading a user of the function ending up creating a new blkg on bypassing queue. This is a bug introduced while relocating bypass patches before this one. Fixed. -v3: ERR_PTR patch folded into this one. @for_root added to blkg_lookup_create() to allow creating root group on a bypassed queue during elevator switch. 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 05:15:06 +08:00
static inline struct blkio_group *blkg_lookup(struct blkio_cgroup *blkcg,
void *key) { return NULL; }
static inline void blkiocg_update_timeslice_used(struct blkio_group *blkg,
unsigned long time,
unsigned long unaccounted_time)
{}
2010-04-09 14:31:19 +08:00
static inline void blkiocg_update_dispatch_stats(struct blkio_group *blkg,
uint64_t bytes, bool direction, bool sync) {}
static inline void blkiocg_update_completion_stats(struct blkio_group *blkg,
uint64_t start_time, uint64_t io_start_time, bool direction,
bool sync) {}
static inline void blkiocg_update_io_merged_stats(struct blkio_group *blkg,
bool direction, bool sync) {}
static inline void blkiocg_update_io_add_stats(struct blkio_group *blkg,
struct blkio_group *curr_blkg, bool direction, bool sync) {}
static inline void blkiocg_update_io_remove_stats(struct blkio_group *blkg,
bool direction, bool sync) {}
#endif
#endif /* _BLK_CGROUP_H */