linux-kernel - Re: [PATCH RFC v2 3/3] io_uring: batch get(ctx->ref) across submits

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <fef4b765-338b-d3b0-7fd5-5672b92fd3e8@gmail.com>
Date:   Sat, 21 Dec 2019 19:48:31 +0300
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Jens Axboe <axboe@...nel.dk>, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Tejun Heo <tj@...nel.org>, Dennis Zhou <dennis@...nel.org>,
        Christoph Lameter <cl@...ux.com>
Subject: Re: [PATCH RFC v2 3/3] io_uring: batch get(ctx->ref) across submits

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!

-- 
Pavel Begunkov



Download attachment "signature.asc" of type "application/pgp-signature" (834 bytes)