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blk-mq: make per-sw-queue bio merge as default .bio_merge

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Because what the per-sw-queue bio merge does is basically same with
scheduler's .bio_merge(), this patch makes per-sw-queue bio merge
as the default .bio_merge if no scheduler is used or io scheduler
doesn't provide .bio_merge().

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Ming Lei 2017-05-26 19:53:20 +08:00 committed by Jens Axboe
parent ab42f35d9c
commit 9bddeb2a5b
3 changed files with 58 additions and 72 deletions
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62
block/blk-mq-sched.c
View file

@ -221,19 +221,71 @@ bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio,
}
EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge);
/*
* Reverse check our software queue for entries that we could potentially
* merge with. Currently includes a hand-wavy stop count of 8, to not spend
* too much time checking for merges.
*/
static bool blk_mq_attempt_merge(struct request_queue *q,
struct blk_mq_ctx *ctx, struct bio *bio)
{
struct request *rq;
int checked = 8;
list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
bool merged = false;
if (!checked--)
break;
if (!blk_rq_merge_ok(rq, bio))
continue;
switch (blk_try_merge(rq, bio)) {
case ELEVATOR_BACK_MERGE:
if (blk_mq_sched_allow_merge(q, rq, bio))
merged = bio_attempt_back_merge(q, rq, bio);
break;
case ELEVATOR_FRONT_MERGE:
if (blk_mq_sched_allow_merge(q, rq, bio))
merged = bio_attempt_front_merge(q, rq, bio);
break;
case ELEVATOR_DISCARD_MERGE:
merged = bio_attempt_discard_merge(q, rq, bio);
break;
default:
continue;
}
if (merged)
ctx->rq_merged++;
return merged;
}
return false;
}
bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)
{
struct elevator_queue *e = q->elevator;
struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
bool ret = false;
if (e->type->ops.mq.bio_merge) {
struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
if (e && e->type->ops.mq.bio_merge) {
blk_mq_put_ctx(ctx);
return e->type->ops.mq.bio_merge(hctx, bio);
}
return false;
if (hctx->flags & BLK_MQ_F_SHOULD_MERGE) {
/* default per sw-queue merge */
spin_lock(&ctx->lock);
ret = blk_mq_attempt_merge(q, ctx, bio);
spin_unlock(&ctx->lock);
}
blk_mq_put_ctx(ctx);
return ret;
}
bool blk_mq_sched_try_insert_merge(struct request_queue *q, struct request *rq)

4
block/blk-mq-sched.h
View file

@ -38,9 +38,7 @@ int blk_mq_sched_init(struct request_queue *q);
static inline bool
blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)
{
struct elevator_queue *e = q->elevator;
if (!e || blk_queue_nomerges(q) || !bio_mergeable(bio))
if (blk_queue_nomerges(q) || !bio_mergeable(bio))
return false;
return __blk_mq_sched_bio_merge(q, bio);

64
block/blk-mq.c
View file

@ -753,50 +753,6 @@ static void blk_mq_timeout_work(struct work_struct *work)
blk_queue_exit(q);
}
/*
* Reverse check our software queue for entries that we could potentially
* merge with. Currently includes a hand-wavy stop count of 8, to not spend
* too much time checking for merges.
*/
static bool blk_mq_attempt_merge(struct request_queue *q,
struct blk_mq_ctx *ctx, struct bio *bio)
{
struct request *rq;
int checked = 8;
list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
bool merged = false;
if (!checked--)
break;
if (!blk_rq_merge_ok(rq, bio))
continue;
switch (blk_try_merge(rq, bio)) {
case ELEVATOR_BACK_MERGE:
if (blk_mq_sched_allow_merge(q, rq, bio))
merged = bio_attempt_back_merge(q, rq, bio);
break;
case ELEVATOR_FRONT_MERGE:
if (blk_mq_sched_allow_merge(q, rq, bio))
merged = bio_attempt_front_merge(q, rq, bio);
break;
case ELEVATOR_DISCARD_MERGE:
merged = bio_attempt_discard_merge(q, rq, bio);
break;
default:
continue;
}
if (merged)
ctx->rq_merged++;
return merged;
}
return false;
}
struct flush_busy_ctx_data {
struct blk_mq_hw_ctx *hctx;
struct list_head *list;
@ -1427,23 +1383,6 @@ static inline bool hctx_allow_merges(struct blk_mq_hw_ctx *hctx)
!blk_queue_nomerges(hctx->queue);
}
/* attempt to merge bio into current sw queue */
static inline bool blk_mq_merge_bio(struct request_queue *q, struct bio *bio)
{
bool ret = false;
struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
if (hctx_allow_merges(hctx) && bio_mergeable(bio)) {
spin_lock(&ctx->lock);
ret = blk_mq_attempt_merge(q, ctx, bio);
spin_unlock(&ctx->lock);
}
blk_mq_put_ctx(ctx);
return ret;
}
static inline void blk_mq_queue_io(struct blk_mq_hw_ctx *hctx,
struct blk_mq_ctx *ctx,
struct request *rq)
@ -1549,9 +1488,6 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
if (blk_mq_sched_bio_merge(q, bio))
return BLK_QC_T_NONE;
if (blk_mq_merge_bio(q, bio))
return BLK_QC_T_NONE;
wb_acct = wbt_wait(q->rq_wb, bio, NULL);
trace_block_getrq(q, bio, bio->bi_opf);