From: Omar Sandoval <osandov@osandov.com>
To: Alexander Gordeev <agordeev@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-block@vger.kernel.org
Subject: Re: [PATCH 04/14] blk-mq: Do not limit number of queues to 'nr_cpu_ids' in allocations
Date: Mon, 19 Sep 2016 10:48:49 -0700 [thread overview]
Message-ID: <20160919174849.GA21803@vader> (raw)
In-Reply-To: <9bb584d504bc2f8ef9d66822e68f082ee9a74ded.1474183901.git.agordeev@redhat.com>
On Sun, Sep 18, 2016 at 09:37:14AM +0200, Alexander Gordeev wrote:
> Currently maximum number of used hardware queues is limited to
> number of CPUs in the system. However, using 'nr_cpu_ids' as
> the limit for (de-)allocations of data structures instead of
> existing data structures' counters (a) worsens readability and
> (b) leads to unused memory when number of hardware queues is
> less than number of CPUs.
>
> CC: linux-block@vger.kernel.org
> Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
> ---
> block/blk-mq.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 276ec7b..2c77b68 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -2054,8 +2054,8 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
> if (!q->queue_ctx)
> goto err_exit;
>
> - q->queue_hw_ctx = kzalloc_node(nr_cpu_ids * sizeof(*(q->queue_hw_ctx)),
> - GFP_KERNEL, set->numa_node);
> + q->queue_hw_ctx = kzalloc_node(set->nr_hw_queues *
> + sizeof(*(q->queue_hw_ctx)), GFP_KERNEL, set->numa_node);
> if (!q->queue_hw_ctx)
> goto err_percpu;
>
> @@ -2319,7 +2319,7 @@ int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
> if (set->nr_hw_queues > nr_cpu_ids)
> set->nr_hw_queues = nr_cpu_ids;
>
> - set->tags = kzalloc_node(nr_cpu_ids * sizeof(struct blk_mq_tags *),
> + set->tags = kzalloc_node(set->nr_hw_queues * sizeof(*set->tags),
> GFP_KERNEL, set->numa_node);
> if (!set->tags)
> return -ENOMEM;
> @@ -2360,7 +2360,7 @@ void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
> {
> int i;
>
> - for (i = 0; i < nr_cpu_ids; i++) {
> + for (i = 0; i < set->nr_hw_queues; i++) {
> if (set->tags[i])
> blk_mq_free_rq_map(set, set->tags[i], i);
> }
I don't think this is safe since we might increase the number of
hardware queues (blk_mq_update_nr_hw_queues()).
--
Omar
next prev parent reply other threads:[~2016-09-19 17:48 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-18 7:37 [PATCH 00/14] blk-mq: Minor fixes and cleanups Alexander Gordeev
2016-09-18 7:37 ` [PATCH 01/14] blk-mq: Fix memory leaks on queue cleanup Alexander Gordeev
2016-09-19 13:51 ` Christoph Hellwig
2016-09-18 7:37 ` [PATCH 02/14] blk-mq: Fix a potential NULL pointer assignment to hctx tags Alexander Gordeev
2016-09-19 18:34 ` Omar Sandoval
2016-09-18 7:37 ` [PATCH 03/14] block: Get rid of unused request_queue::nr_queues member Alexander Gordeev
2016-09-19 18:37 ` Omar Sandoval
2016-09-18 7:37 ` [PATCH 04/14] blk-mq: Do not limit number of queues to 'nr_cpu_ids' in allocations Alexander Gordeev
2016-09-19 17:48 ` Omar Sandoval [this message]
2016-09-20 11:44 ` Alexander Gordeev
2016-09-20 17:26 ` Omar Sandoval
2016-09-18 7:37 ` [PATCH 05/14] blk-mq: Remove a redundant assignment Alexander Gordeev
2016-09-19 18:38 ` Omar Sandoval
2016-09-18 7:37 ` [PATCH 06/14] blk-mq: Fix hardware context data node selection Alexander Gordeev
2016-09-19 18:54 ` Omar Sandoval
2016-09-18 7:37 ` [PATCH 07/14] blk-mq: Cleanup a loop exit condition Alexander Gordeev
2016-09-19 19:00 ` Omar Sandoval
2016-09-20 11:33 ` Alexander Gordeev
2016-09-18 7:37 ` [PATCH 08/14] blk-mq: Get rid of unnecessary blk_mq_free_hw_queues() Alexander Gordeev
2016-09-18 7:37 ` [PATCH 09/14] blk-mq: Move duplicating code to blk_mq_exit_hctx() Alexander Gordeev
2016-09-19 17:57 ` Omar Sandoval
2016-09-18 7:37 ` [PATCH 10/14] blk-mq: Uninit hardware context in order reverse to init Alexander Gordeev
2016-09-19 17:59 ` Omar Sandoval
2016-09-18 7:37 ` [PATCH 11/14] blk-mq: Move hardware context init code into single location Alexander Gordeev
2016-09-18 7:37 ` [PATCH 12/14] blk-mq: Rework blk_mq_init_hctx() function Alexander Gordeev
2016-09-18 7:37 ` [PATCH 13/14] blk-mq: Pair blk_mq_hctx_kobj_init() with blk_mq_hctx_kobj_put() Alexander Gordeev
2016-09-18 7:37 ` [PATCH 14/14] blk-mq: Set flush_start_tag to BLK_MQ_MAX_DEPTH Alexander Gordeev
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