From: Bart Van Assche <bvanassche@acm.org>
To: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, linux-scsi@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 09/14] blk-mq: ensure that plug lists don't straddle hardware queues
Date: Mon, 29 Oct 2018 12:27:58 -0700 [thread overview]
Message-ID: <1540841278.196084.84.camel@acm.org> (raw)
In-Reply-To: <20181029163738.10172-10-axboe@kernel.dk>
On Mon, 2018-10-29 at 10:37 -0600, Jens Axboe wrote:
> void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
> {
> struct blk_mq_ctx *this_ctx;
> @@ -1628,7 +1649,7 @@ void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
> struct request *rq;
> LIST_HEAD(list);
> LIST_HEAD(ctx_list);
> - unsigned int depth;
> + unsigned int depth, this_flags;
>
> list_splice_init(&plug->mq_list, &list);
>
> @@ -1636,13 +1657,14 @@ void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
>
> this_q = NULL;
> this_ctx = NULL;
> + this_flags = 0;
> depth = 0;
>
> while (!list_empty(&list)) {
> rq = list_entry_rq(list.next);
> list_del_init(&rq->queuelist);
> BUG_ON(!rq->q);
> - if (rq->mq_ctx != this_ctx) {
> + if (!ctx_match(rq, this_ctx, this_flags)) {
> if (this_ctx) {
> trace_block_unplug(this_q, depth, !from_schedule);
> blk_mq_sched_insert_requests(this_q, this_ctx,
> @@ -1650,6 +1672,7 @@ void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
> from_schedule);
> }
>
> + this_flags = rq->cmd_flags;
> this_ctx = rq->mq_ctx;
> this_q = rq->q;
> depth = 0;
This patch will cause the function stored in the flags_to_type pointer to be
called 2 * (n - 1) times where n is the number of elements in 'list' when
blk_mq_sched_insert_requests() is called. Have you considered to rearrange
the code such that that number of calls is reduced to n?
Thanks,
Bart.
next prev parent reply other threads:[~2018-10-29 19:28 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-29 16:37 [PATCHSET v2 0/14] blk-mq: Add support for multiple queue maps Jens Axboe
2018-10-29 16:37 ` [PATCH 01/14] blk-mq: kill q->mq_map Jens Axboe
2018-10-29 16:46 ` Bart Van Assche
2018-10-29 16:51 ` Jens Axboe
2018-10-29 16:37 ` [PATCH 02/14] blk-mq: abstract out queue map Jens Axboe
2018-10-29 18:33 ` Bart Van Assche
2018-10-29 16:37 ` [PATCH 03/14] blk-mq: provide dummy blk_mq_map_queue_type() helper Jens Axboe
2018-10-29 17:22 ` Bart Van Assche
2018-10-29 17:27 ` Jens Axboe
2018-10-29 16:37 ` [PATCH 04/14] blk-mq: pass in request/bio flags to queue mapping Jens Axboe
2018-10-29 17:30 ` Bart Van Assche
2018-10-29 17:33 ` Jens Axboe
2018-10-29 16:37 ` [PATCH 05/14] blk-mq: allow software queue to map to multiple hardware queues Jens Axboe
2018-10-29 17:34 ` Bart Van Assche
2018-10-29 17:35 ` Jens Axboe
2018-10-29 16:37 ` [PATCH 06/14] blk-mq: add 'type' attribute to the sysfs hctx directory Jens Axboe
2018-10-29 17:40 ` Bart Van Assche
2018-10-29 16:37 ` [PATCH 07/14] blk-mq: support multiple hctx maps Jens Axboe
2018-10-29 18:15 ` Bart Van Assche
2018-10-29 19:24 ` Jens Axboe
2018-10-29 16:37 ` [PATCH 08/14] blk-mq: separate number of hardware queues from nr_cpu_ids Jens Axboe
2018-10-29 18:31 ` Bart Van Assche
2018-10-29 16:37 ` [PATCH 09/14] blk-mq: ensure that plug lists don't straddle hardware queues Jens Axboe
2018-10-29 19:27 ` Bart Van Assche [this message]
2018-10-29 19:30 ` Jens Axboe
2018-10-29 19:49 ` Jens Axboe
2018-10-30 8:08 ` Ming Lei
2018-10-30 17:22 ` Jens Axboe
2018-10-29 16:37 ` [PATCH 10/14] blk-mq: initial support for multiple queue maps Jens Axboe
2018-10-29 19:40 ` Bart Van Assche
2018-10-29 19:53 ` Jens Axboe
2018-10-29 20:00 ` Bart Van Assche
2018-10-29 20:09 ` Jens Axboe
2018-10-29 20:25 ` Bart Van Assche
2018-10-29 20:29 ` Jens Axboe
2018-10-29 16:37 ` [PATCH 11/14] irq: add support for allocating (and affinitizing) sets of IRQs Jens Axboe
2018-10-29 17:08 ` Thomas Gleixner
2018-10-29 17:09 ` Jens Axboe
2018-10-30 9:25 ` Ming Lei
2018-10-30 14:26 ` Keith Busch
2018-10-30 14:36 ` Jens Axboe
2018-10-30 14:45 ` Keith Busch
2018-10-30 14:53 ` Jens Axboe
2018-10-30 15:08 ` Keith Busch
2018-10-30 15:18 ` Jens Axboe
2018-10-30 16:02 ` Keith Busch
2018-10-30 16:42 ` Jens Axboe
2018-10-30 17:09 ` Jens Axboe
2018-10-30 17:22 ` Keith Busch
2018-10-30 17:33 ` Jens Axboe
2018-10-30 17:35 ` Keith Busch
2018-10-30 17:25 ` Thomas Gleixner
2018-10-30 17:34 ` Jens Axboe
2018-10-30 17:43 ` Jens Axboe
2018-10-30 17:46 ` Thomas Gleixner
2018-10-30 17:47 ` Jens Axboe
2018-10-29 16:37 ` [PATCH 12/14] nvme: utilize two queue maps, one for reads and one for writes Jens Axboe
2018-10-29 16:37 ` [PATCH 13/14] block: add REQ_HIPRI and inherit it from IOCB_HIPRI Jens Axboe
2018-10-29 16:37 ` [PATCH 14/14] nvme: add separate poll queue map Jens Axboe
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