diff options
author | Ming Lei <ming.lei@redhat.com> | 2021-01-22 03:33:12 +0100 |
---|---|---|
committer | Martin K. Petersen <martin.petersen@oracle.com> | 2021-03-04 23:36:59 +0100 |
commit | 2a5a24aa83382a88c43d18a901fab66e6ffe1199 (patch) | |
tree | 85d9a1aa8d76bb25fe9fdc56f9a1b74f575ce485 /block/blk-mq.c | |
parent | scsi: blk-mq: Add callbacks for storing & retrieving budget token (diff) | |
download | linux-2a5a24aa83382a88c43d18a901fab66e6ffe1199.tar.xz linux-2a5a24aa83382a88c43d18a901fab66e6ffe1199.zip |
scsi: blk-mq: Return budget token from .get_budget callback
SCSI uses a global atomic variable to track queue depth for each
LUN/request queue.
This doesn't scale well when there are lots of CPU cores and the disk is
very fast. It has been observed that IOPS is affected a lot by tracking
queue depth via sdev->device_busy in the I/O path.
Return budget token from .get_budget callback. The budget token can be
passed to driver so that we can replace the atomic variable with
sbitmap_queue and alleviate the scaling problems that way.
Link: https://lore.kernel.org/r/20210122023317.687987-9-ming.lei@redhat.com
Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'block/blk-mq.c')
-rw-r--r-- | block/blk-mq.c | 36 |
1 files changed, 25 insertions, 11 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c index 2e8c94e00f58..2e825a7a3606 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1277,10 +1277,15 @@ static enum prep_dispatch blk_mq_prep_dispatch_rq(struct request *rq, bool need_budget) { struct blk_mq_hw_ctx *hctx = rq->mq_hctx; + int budget_token = -1; - if (need_budget && !blk_mq_get_dispatch_budget(rq->q)) { - blk_mq_put_driver_tag(rq); - return PREP_DISPATCH_NO_BUDGET; + if (need_budget) { + budget_token = blk_mq_get_dispatch_budget(rq->q); + if (budget_token < 0) { + blk_mq_put_driver_tag(rq); + return PREP_DISPATCH_NO_BUDGET; + } + blk_mq_set_rq_budget_token(rq, budget_token); } if (!blk_mq_get_driver_tag(rq)) { @@ -1297,7 +1302,7 @@ static enum prep_dispatch blk_mq_prep_dispatch_rq(struct request *rq, * together during handling partial dispatch */ if (need_budget) - blk_mq_put_dispatch_budget(rq->q); + blk_mq_put_dispatch_budget(rq->q, budget_token); return PREP_DISPATCH_NO_TAG; } } @@ -1307,12 +1312,16 @@ static enum prep_dispatch blk_mq_prep_dispatch_rq(struct request *rq, /* release all allocated budgets before calling to blk_mq_dispatch_rq_list */ static void blk_mq_release_budgets(struct request_queue *q, - unsigned int nr_budgets) + struct list_head *list) { - int i; + struct request *rq; - for (i = 0; i < nr_budgets; i++) - blk_mq_put_dispatch_budget(q); + list_for_each_entry(rq, list, queuelist) { + int budget_token = blk_mq_get_rq_budget_token(rq); + + if (budget_token >= 0) + blk_mq_put_dispatch_budget(q, budget_token); + } } /* @@ -1410,7 +1419,8 @@ out: (hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED); bool no_budget_avail = prep == PREP_DISPATCH_NO_BUDGET; - blk_mq_release_budgets(q, nr_budgets); + if (nr_budgets) + blk_mq_release_budgets(q, list); spin_lock(&hctx->lock); list_splice_tail_init(list, &hctx->dispatch); @@ -2009,6 +2019,7 @@ static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, { struct request_queue *q = rq->q; bool run_queue = true; + int budget_token; /* * RCU or SRCU read lock is needed before checking quiesced flag. @@ -2026,11 +2037,14 @@ static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, if (q->elevator && !bypass_insert) goto insert; - if (!blk_mq_get_dispatch_budget(q)) + budget_token = blk_mq_get_dispatch_budget(q); + if (budget_token < 0) goto insert; + blk_mq_set_rq_budget_token(rq, budget_token); + if (!blk_mq_get_driver_tag(rq)) { - blk_mq_put_dispatch_budget(q); + blk_mq_put_dispatch_budget(q, budget_token); goto insert; } |