mirror of https://gitee.com/openkylin/linux.git
mq-deadline: add blk-mq adaptation of the deadline IO scheduler
This is basically identical to deadline-iosched, except it registers as a MQ capable scheduler. This is still a single queue design. Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Omar Sandoval <osandov@fb.com>
This commit is contained in:
Jens Axboe
parent
bd166ef183
commit
945ffb60c1
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@ -32,6 +32,12 @@ config IOSCHED_CFQ
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This is the default I/O scheduler.
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config MQ_IOSCHED_DEADLINE
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tristate "MQ deadline I/O scheduler"
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default y
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---help---
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MQ version of the deadline IO scheduler.
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config CFQ_GROUP_IOSCHED
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bool "CFQ Group Scheduling support"
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depends on IOSCHED_CFQ && BLK_CGROUP
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@ -18,6 +18,7 @@ obj-$(CONFIG_BLK_DEV_THROTTLING) += blk-throttle.o
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obj-$(CONFIG_IOSCHED_NOOP) += noop-iosched.o
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obj-$(CONFIG_IOSCHED_DEADLINE) += deadline-iosched.o
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obj-$(CONFIG_IOSCHED_CFQ) += cfq-iosched.o
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obj-$(CONFIG_MQ_IOSCHED_DEADLINE) += mq-deadline.o
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obj-$(CONFIG_BLOCK_COMPAT) += compat_ioctl.o
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obj-$(CONFIG_BLK_CMDLINE_PARSER) += cmdline-parser.o
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@ -0,0 +1,553 @@
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/*
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* MQ Deadline i/o scheduler - adaptation of the legacy deadline scheduler,
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* for the blk-mq scheduling framework
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*
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* Copyright (C) 2016 Jens Axboe <axboe@kernel.dk>
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*/
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#include <linux/kernel.h>
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#include <linux/fs.h>
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#include <linux/blkdev.h>
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#include <linux/blk-mq.h>
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#include <linux/elevator.h>
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#include <linux/bio.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/compiler.h>
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#include <linux/rbtree.h>
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#include <linux/sbitmap.h>
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#include "blk.h"
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#include "blk-mq.h"
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#include "blk-mq-tag.h"
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#include "blk-mq-sched.h"
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/*
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* See Documentation/block/deadline-iosched.txt
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*/
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static const int read_expire = HZ / 2; /* max time before a read is submitted. */
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static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
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static const int writes_starved = 2; /* max times reads can starve a write */
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static const int fifo_batch = 16; /* # of sequential requests treated as one
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by the above parameters. For throughput. */
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struct deadline_data {
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/*
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* run time data
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*/
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/*
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* requests (deadline_rq s) are present on both sort_list and fifo_list
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*/
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struct rb_root sort_list[2];
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struct list_head fifo_list[2];
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/*
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* next in sort order. read, write or both are NULL
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*/
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struct request *next_rq[2];
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unsigned int batching; /* number of sequential requests made */
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unsigned int starved; /* times reads have starved writes */
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/*
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* settings that change how the i/o scheduler behaves
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*/
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int fifo_expire[2];
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int fifo_batch;
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int writes_starved;
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int front_merges;
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spinlock_t lock;
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struct list_head dispatch;
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};
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static inline struct rb_root *
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deadline_rb_root(struct deadline_data *dd, struct request *rq)
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{
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return &dd->sort_list[rq_data_dir(rq)];
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}
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/*
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* get the request after `rq' in sector-sorted order
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*/
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static inline struct request *
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deadline_latter_request(struct request *rq)
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{
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struct rb_node *node = rb_next(&rq->rb_node);
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if (node)
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return rb_entry_rq(node);
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return NULL;
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}
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static void
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deadline_add_rq_rb(struct deadline_data *dd, struct request *rq)
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{
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struct rb_root *root = deadline_rb_root(dd, rq);
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elv_rb_add(root, rq);
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}
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static inline void
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deadline_del_rq_rb(struct deadline_data *dd, struct request *rq)
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{
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const int data_dir = rq_data_dir(rq);
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if (dd->next_rq[data_dir] == rq)
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dd->next_rq[data_dir] = deadline_latter_request(rq);
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elv_rb_del(deadline_rb_root(dd, rq), rq);
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}
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/*
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* remove rq from rbtree and fifo.
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*/
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static void deadline_remove_request(struct request_queue *q, struct request *rq)
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{
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struct deadline_data *dd = q->elevator->elevator_data;
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list_del_init(&rq->queuelist);
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/*
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* We might not be on the rbtree, if we are doing an insert merge
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*/
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if (!RB_EMPTY_NODE(&rq->rb_node))
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deadline_del_rq_rb(dd, rq);
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elv_rqhash_del(q, rq);
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if (q->last_merge == rq)
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q->last_merge = NULL;
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}
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static void dd_request_merged(struct request_queue *q, struct request *req,
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int type)
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{
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struct deadline_data *dd = q->elevator->elevator_data;
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/*
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* if the merge was a front merge, we need to reposition request
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*/
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if (type == ELEVATOR_FRONT_MERGE) {
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elv_rb_del(deadline_rb_root(dd, req), req);
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deadline_add_rq_rb(dd, req);
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}
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}
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static void dd_merged_requests(struct request_queue *q, struct request *req,
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struct request *next)
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{
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/*
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* if next expires before rq, assign its expire time to rq
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* and move into next position (next will be deleted) in fifo
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*/
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if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
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if (time_before((unsigned long)next->fifo_time,
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(unsigned long)req->fifo_time)) {
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list_move(&req->queuelist, &next->queuelist);
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req->fifo_time = next->fifo_time;
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}
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}
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/*
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* kill knowledge of next, this one is a goner
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*/
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deadline_remove_request(q, next);
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}
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/*
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* move an entry to dispatch queue
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*/
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static void
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deadline_move_request(struct deadline_data *dd, struct request *rq)
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{
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const int data_dir = rq_data_dir(rq);
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dd->next_rq[READ] = NULL;
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dd->next_rq[WRITE] = NULL;
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dd->next_rq[data_dir] = deadline_latter_request(rq);
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/*
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* take it off the sort and fifo list
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*/
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deadline_remove_request(rq->q, rq);
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}
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/*
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* deadline_check_fifo returns 0 if there are no expired requests on the fifo,
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* 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir])
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*/
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static inline int deadline_check_fifo(struct deadline_data *dd, int ddir)
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{
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struct request *rq = rq_entry_fifo(dd->fifo_list[ddir].next);
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/*
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* rq is expired!
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*/
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if (time_after_eq(jiffies, (unsigned long)rq->fifo_time))
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return 1;
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return 0;
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}
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/*
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* deadline_dispatch_requests selects the best request according to
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* read/write expire, fifo_batch, etc
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*/
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static struct request *__dd_dispatch_request(struct blk_mq_hw_ctx *hctx)
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{
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struct deadline_data *dd = hctx->queue->elevator->elevator_data;
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struct request *rq;
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bool reads, writes;
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int data_dir;
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if (!list_empty(&dd->dispatch)) {
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rq = list_first_entry(&dd->dispatch, struct request, queuelist);
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list_del_init(&rq->queuelist);
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goto done;
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}
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reads = !list_empty(&dd->fifo_list[READ]);
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writes = !list_empty(&dd->fifo_list[WRITE]);
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/*
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* batches are currently reads XOR writes
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*/
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if (dd->next_rq[WRITE])
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rq = dd->next_rq[WRITE];
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else
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rq = dd->next_rq[READ];
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if (rq && dd->batching < dd->fifo_batch)
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/* we have a next request are still entitled to batch */
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goto dispatch_request;
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/*
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* at this point we are not running a batch. select the appropriate
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* data direction (read / write)
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*/
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if (reads) {
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BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[READ]));
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if (writes && (dd->starved++ >= dd->writes_starved))
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goto dispatch_writes;
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data_dir = READ;
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goto dispatch_find_request;
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}
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/*
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* there are either no reads or writes have been starved
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*/
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if (writes) {
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dispatch_writes:
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BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[WRITE]));
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dd->starved = 0;
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data_dir = WRITE;
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goto dispatch_find_request;
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}
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return NULL;
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dispatch_find_request:
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/*
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* we are not running a batch, find best request for selected data_dir
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*/
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if (deadline_check_fifo(dd, data_dir) || !dd->next_rq[data_dir]) {
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/*
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* A deadline has expired, the last request was in the other
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* direction, or we have run out of higher-sectored requests.
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* Start again from the request with the earliest expiry time.
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*/
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rq = rq_entry_fifo(dd->fifo_list[data_dir].next);
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} else {
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/*
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* The last req was the same dir and we have a next request in
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* sort order. No expired requests so continue on from here.
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*/
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rq = dd->next_rq[data_dir];
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}
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dd->batching = 0;
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dispatch_request:
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/*
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* rq is the selected appropriate request.
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*/
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dd->batching++;
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deadline_move_request(dd, rq);
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done:
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rq->rq_flags |= RQF_STARTED;
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return rq;
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}
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static void dd_dispatch_requests(struct blk_mq_hw_ctx *hctx,
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struct list_head *rq_list)
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{
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struct deadline_data *dd = hctx->queue->elevator->elevator_data;
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spin_lock(&dd->lock);
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blk_mq_sched_move_to_dispatch(hctx, rq_list, __dd_dispatch_request);
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spin_unlock(&dd->lock);
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}
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static void dd_exit_queue(struct elevator_queue *e)
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{
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struct deadline_data *dd = e->elevator_data;
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BUG_ON(!list_empty(&dd->fifo_list[READ]));
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BUG_ON(!list_empty(&dd->fifo_list[WRITE]));
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kfree(dd);
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}
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/*
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* initialize elevator private data (deadline_data).
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*/
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static int dd_init_queue(struct request_queue *q, struct elevator_type *e)
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{
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struct deadline_data *dd;
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struct elevator_queue *eq;
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eq = elevator_alloc(q, e);
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if (!eq)
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return -ENOMEM;
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dd = kzalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
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if (!dd) {
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kobject_put(&eq->kobj);
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return -ENOMEM;
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}
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eq->elevator_data = dd;
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INIT_LIST_HEAD(&dd->fifo_list[READ]);
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INIT_LIST_HEAD(&dd->fifo_list[WRITE]);
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dd->sort_list[READ] = RB_ROOT;
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dd->sort_list[WRITE] = RB_ROOT;
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dd->fifo_expire[READ] = read_expire;
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dd->fifo_expire[WRITE] = write_expire;
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dd->writes_starved = writes_starved;
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dd->front_merges = 1;
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dd->fifo_batch = fifo_batch;
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spin_lock_init(&dd->lock);
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INIT_LIST_HEAD(&dd->dispatch);
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q->elevator = eq;
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return 0;
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}
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static int dd_request_merge(struct request_queue *q, struct request **rq,
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struct bio *bio)
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{
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struct deadline_data *dd = q->elevator->elevator_data;
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sector_t sector = bio_end_sector(bio);
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struct request *__rq;
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if (!dd->front_merges)
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return ELEVATOR_NO_MERGE;
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__rq = elv_rb_find(&dd->sort_list[bio_data_dir(bio)], sector);
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if (__rq) {
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BUG_ON(sector != blk_rq_pos(__rq));
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if (elv_bio_merge_ok(__rq, bio)) {
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*rq = __rq;
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return ELEVATOR_FRONT_MERGE;
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}
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}
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return ELEVATOR_NO_MERGE;
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}
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static bool dd_bio_merge(struct blk_mq_hw_ctx *hctx, struct bio *bio)
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{
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struct request_queue *q = hctx->queue;
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struct deadline_data *dd = q->elevator->elevator_data;
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int ret;
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spin_lock(&dd->lock);
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ret = blk_mq_sched_try_merge(q, bio);
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spin_unlock(&dd->lock);
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return ret;
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}
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/*
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* add rq to rbtree and fifo
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*/
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static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
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bool at_head)
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{
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struct request_queue *q = hctx->queue;
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struct deadline_data *dd = q->elevator->elevator_data;
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const int data_dir = rq_data_dir(rq);
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if (blk_mq_sched_try_insert_merge(q, rq))
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return;
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blk_mq_sched_request_inserted(rq);
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if (blk_mq_sched_bypass_insert(hctx, rq))
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return;
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if (at_head || rq->cmd_type != REQ_TYPE_FS) {
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if (at_head)
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list_add(&rq->queuelist, &dd->dispatch);
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else
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list_add_tail(&rq->queuelist, &dd->dispatch);
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} else {
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deadline_add_rq_rb(dd, rq);
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if (rq_mergeable(rq)) {
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elv_rqhash_add(q, rq);
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if (!q->last_merge)
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q->last_merge = rq;
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}
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/*
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* set expire time and add to fifo list
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*/
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rq->fifo_time = jiffies + dd->fifo_expire[data_dir];
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list_add_tail(&rq->queuelist, &dd->fifo_list[data_dir]);
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}
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}
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static void dd_insert_requests(struct blk_mq_hw_ctx *hctx,
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struct list_head *list, bool at_head)
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{
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struct request_queue *q = hctx->queue;
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struct deadline_data *dd = q->elevator->elevator_data;
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spin_lock(&dd->lock);
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while (!list_empty(list)) {
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struct request *rq;
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rq = list_first_entry(list, struct request, queuelist);
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list_del_init(&rq->queuelist);
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dd_insert_request(hctx, rq, at_head);
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}
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spin_unlock(&dd->lock);
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}
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static bool dd_has_work(struct blk_mq_hw_ctx *hctx)
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{
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struct deadline_data *dd = hctx->queue->elevator->elevator_data;
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return !list_empty_careful(&dd->dispatch) ||
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!list_empty_careful(&dd->fifo_list[0]) ||
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!list_empty_careful(&dd->fifo_list[1]);
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}
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/*
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* sysfs parts below
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*/
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static ssize_t
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deadline_var_show(int var, char *page)
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{
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return sprintf(page, "%d\n", var);
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}
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static ssize_t
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deadline_var_store(int *var, const char *page, size_t count)
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{
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char *p = (char *) page;
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*var = simple_strtol(p, &p, 10);
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return count;
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}
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#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
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static ssize_t __FUNC(struct elevator_queue *e, char *page) \
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{ \
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struct deadline_data *dd = e->elevator_data; \
|
||||
int __data = __VAR; \
|
||||
if (__CONV) \
|
||||
__data = jiffies_to_msecs(__data); \
|
||||
return deadline_var_show(__data, (page)); \
|
||||
}
|
||||
SHOW_FUNCTION(deadline_read_expire_show, dd->fifo_expire[READ], 1);
|
||||
SHOW_FUNCTION(deadline_write_expire_show, dd->fifo_expire[WRITE], 1);
|
||||
SHOW_FUNCTION(deadline_writes_starved_show, dd->writes_starved, 0);
|
||||
SHOW_FUNCTION(deadline_front_merges_show, dd->front_merges, 0);
|
||||
SHOW_FUNCTION(deadline_fifo_batch_show, dd->fifo_batch, 0);
|
||||
#undef SHOW_FUNCTION
|
||||
|
||||
#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
|
||||
static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
|
||||
{ \
|
||||
struct deadline_data *dd = e->elevator_data; \
|
||||
int __data; \
|
||||
int ret = deadline_var_store(&__data, (page), count); \
|
||||
if (__data < (MIN)) \
|
||||
__data = (MIN); \
|
||||
else if (__data > (MAX)) \
|
||||
__data = (MAX); \
|
||||
if (__CONV) \
|
||||
*(__PTR) = msecs_to_jiffies(__data); \
|
||||
else \
|
||||
*(__PTR) = __data; \
|
||||
return ret; \
|
||||
}
|
||||
STORE_FUNCTION(deadline_read_expire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1);
|
||||
STORE_FUNCTION(deadline_write_expire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1);
|
||||
STORE_FUNCTION(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0);
|
||||
STORE_FUNCTION(deadline_front_merges_store, &dd->front_merges, 0, 1, 0);
|
||||
STORE_FUNCTION(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX, 0);
|
||||
#undef STORE_FUNCTION
|
||||
|
||||
#define DD_ATTR(name) \
|
||||
__ATTR(name, S_IRUGO|S_IWUSR, deadline_##name##_show, \
|
||||
deadline_##name##_store)
|
||||
|
||||
static struct elv_fs_entry deadline_attrs[] = {
|
||||
DD_ATTR(read_expire),
|
||||
DD_ATTR(write_expire),
|
||||
DD_ATTR(writes_starved),
|
||||
DD_ATTR(front_merges),
|
||||
DD_ATTR(fifo_batch),
|
||||
__ATTR_NULL
|
||||
};
|
||||
|
||||
static struct elevator_type mq_deadline = {
|
||||
.ops.mq = {
|
||||
.insert_requests = dd_insert_requests,
|
||||
.dispatch_requests = dd_dispatch_requests,
|
||||
.next_request = elv_rb_latter_request,
|
||||
.former_request = elv_rb_former_request,
|
||||
.bio_merge = dd_bio_merge,
|
||||
.request_merge = dd_request_merge,
|
||||
.requests_merged = dd_merged_requests,
|
||||
.request_merged = dd_request_merged,
|
||||
.has_work = dd_has_work,
|
||||
.init_sched = dd_init_queue,
|
||||
.exit_sched = dd_exit_queue,
|
||||
},
|
||||
|
||||
.uses_mq = true,
|
||||
.elevator_attrs = deadline_attrs,
|
||||
.elevator_name = "mq-deadline",
|
||||
.elevator_owner = THIS_MODULE,
|
||||
};
|
||||
|
||||
static int __init deadline_init(void)
|
||||
{
|
||||
return elv_register(&mq_deadline);
|
||||
}
|
||||
|
||||
static void __exit deadline_exit(void)
|
||||
{
|
||||
elv_unregister(&mq_deadline);
|
||||
}
|
||||
|
||||
module_init(deadline_init);
|
||||
module_exit(deadline_exit);
|
||||
|
||||
MODULE_AUTHOR("Jens Axboe");
|
||||
MODULE_LICENSE("GPL");
|
||||
MODULE_DESCRIPTION("MQ deadline IO scheduler");
|
||||
Loading…
Reference in New Issue