From: Jens Axboe <[email protected]>
To: Pavel Begunkov <[email protected]>,
[email protected], [email protected]
Cc: Tejun Heo <[email protected]>, Dennis Zhou <[email protected]>,
Christoph Lameter <[email protected]>
Subject: Re: [PATCH RFC v2 3/3] io_uring: batch get(ctx->ref) across submits
Date: Sat, 21 Dec 2019 10:01:07 -0700 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On 12/21/19 9:48 AM, Pavel Begunkov wrote:
> On 21/12/2019 19:38, Jens Axboe wrote:
>> On 12/21/19 9:20 AM, Pavel Begunkov wrote:
>>> On 21/12/2019 19:15, Pavel Begunkov wrote:
>>>> Double account ctx->refs keeping number of taken refs in ctx. As
>>>> io_uring gets per-request ctx->refs during submission, while holding
>>>> ctx->uring_lock, this allows in most of the time to bypass
>>>> percpu_ref_get*() and its overhead.
>>>
>>> Jens, could you please benchmark with this one? Especially for offloaded QD1
>>> case. I haven't got any difference for nops test and don't have a decent SSD
>>> at hands to test it myself. We could drop it, if there is no benefit.
>>>
>>> This rewrites that @extra_refs from the second one, so I left it for now.
>>
>> Sure, let me run a peak test, qd1 test, qd1+sqpoll test on
>> for-5.6/io_uring, same branch with 1-2, and same branch with 1-3. That
>> should give us a good comparison. One core used for all, and we're going
>> to be core speed bound for the performance in all cases on this setup.
>> So it'll be a good comparison.
>>
> Great, thanks!
For some reason, not seeing much of a change between for-5.6/io_uring
and 1+2 and 1+2+3, it's about the same and results seem very stable.
For reference, top of profile with 1-3 applied looks like this:
+ 3.92% io_uring [kernel.vmlinux] [k] blkdev_direct_IO
+ 3.87% io_uring [kernel.vmlinux] [k] blk_mq_get_request
+ 3.43% io_uring [kernel.vmlinux] [k] io_iopoll_getevents
+ 3.03% io_uring [kernel.vmlinux] [k] __slab_free
+ 2.87% io_uring io_uring [.] submitter_fn
+ 2.79% io_uring [kernel.vmlinux] [k] io_submit_sqes
+ 2.75% io_uring [kernel.vmlinux] [k] bio_alloc_bioset
+ 2.70% io_uring [nvme_core] [k] nvme_setup_cmd
+ 2.59% io_uring [kernel.vmlinux] [k] blk_mq_make_request
+ 2.46% io_uring [kernel.vmlinux] [k] io_prep_rw
+ 2.32% io_uring [kernel.vmlinux] [k] io_read
+ 2.25% io_uring [kernel.vmlinux] [k] blk_mq_free_request
+ 2.19% io_uring [kernel.vmlinux] [k] io_put_req
+ 2.06% io_uring [kernel.vmlinux] [k] kmem_cache_alloc
+ 2.01% io_uring [kernel.vmlinux] [k] generic_make_request_checks
+ 1.90% io_uring [kernel.vmlinux] [k] __sbitmap_get_word
+ 1.86% io_uring [kernel.vmlinux] [k] sbitmap_queue_clear
+ 1.85% io_uring [kernel.vmlinux] [k] io_issue_sqe
--
Jens Axboe
next prev parent reply other threads:[~2019-12-21 17:01 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-17 22:28 [PATCH 0/2] optimise ctx's refs grabbing in io_uring Pavel Begunkov
2019-12-17 22:28 ` [PATCH 1/2] pcpu_ref: add percpu_ref_tryget_many() Pavel Begunkov
2019-12-17 23:42 ` Jens Axboe
2019-12-18 16:26 ` Tejun Heo
2019-12-18 17:49 ` Dennis Zhou
2019-12-21 15:36 ` Pavel Begunkov
2019-12-17 22:28 ` [PATCH 2/2] io_uring: batch getting pcpu references Pavel Begunkov
2019-12-17 23:21 ` Jens Axboe
2019-12-17 23:31 ` Jens Axboe
2019-12-18 9:25 ` Pavel Begunkov
2019-12-18 9:23 ` Pavel Begunkov
2019-12-18 0:02 ` Jens Axboe
2019-12-18 10:41 ` Pavel Begunkov
2019-12-21 16:15 ` [PATCH v2 0/3] optimise ctx's refs grabbing in io_uring Pavel Begunkov
2019-12-21 16:15 ` [PATCH v2 1/3] pcpu_ref: add percpu_ref_tryget_many() Pavel Begunkov
2019-12-21 16:15 ` [PATCH v2 2/3] io_uring: batch getting pcpu references Pavel Begunkov
2019-12-21 16:15 ` [PATCH RFC v2 3/3] io_uring: batch get(ctx->ref) across submits Pavel Begunkov
2019-12-21 16:20 ` Pavel Begunkov
2019-12-21 16:38 ` Jens Axboe
2019-12-21 16:48 ` Pavel Begunkov
2019-12-21 17:01 ` Jens Axboe [this message]
2019-12-21 17:26 ` Pavel Begunkov
2019-12-21 20:12 ` [PATCH v3 0/2] optimise ctx's refs grabbing in io_uring Pavel Begunkov
2019-12-21 20:12 ` [PATCH v3 1/2] pcpu_ref: add percpu_ref_tryget_many() Pavel Begunkov
2019-12-21 20:12 ` [PATCH v3 2/2] io_uring: batch getting pcpu references Pavel Begunkov
2019-12-21 21:56 ` Pavel Begunkov
2019-12-28 11:13 ` [PATCH v4 0/2] optimise ctx's refs grabbing in io_uring Pavel Begunkov
2019-12-28 11:13 ` [PATCH v4 1/2] pcpu_ref: add percpu_ref_tryget_many() Pavel Begunkov
2019-12-28 11:13 ` [PATCH v4 2/2] io_uring: batch getting pcpu references Pavel Begunkov
2019-12-28 11:15 ` Pavel Begunkov
2019-12-28 17:03 ` Jens Axboe
2019-12-28 18:37 ` Pavel Begunkov
2019-12-30 3:33 ` Brian Gianforcaro
2019-12-30 18:45 ` Pavel Begunkov
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