From: Pavel Begunkov <asml.silence@gmail.com>
To: Noah Goldstein <goldstein.w.n@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>,
"open list:IO_URING" <io-uring@vger.kernel.org>
Subject: Re: [PATCH v2 12/24] io_uring: optimise batch completion
Date: Tue, 28 Sep 2021 10:35:21 +0100 [thread overview]
Message-ID: <f1193cda-2663-a830-6458-a20fe4157327@gmail.com> (raw)
In-Reply-To: <CAFUsyfLSXMvd_MBAp83qriW7LD=bg2=25TC4e_X4oMO1atoPYg@mail.gmail.com>
On 9/25/21 8:58 PM, Noah Goldstein wrote:
> On Fri, Sep 24, 2021 at 5:45 PM Pavel Begunkov <asml.silence@gmail.com>
[...]
>> + if (unlikely(!nr_events))
>> + return 0;
>> +
>> + io_commit_cqring(ctx);
>> + io_cqring_ev_posted_iopoll(ctx);
>> + list.first = start ? start->next : ctx->iopoll_list.first;
>> + list.last = prev;
>> wq_list_cut(&ctx->iopoll_list, prev, start);
>> - if (nr_events)
>> - io_iopoll_complete(ctx, &done);
>> + io_free_batch_list(ctx, &list);
>>
>
> If it's logically feasible it may be slightly faster on speculative machines
> to pass `nr_events` to `io_free_batch_list` so instead of having the loop
> condition on `node` you can use the counter and hopefully recover from
> the branch miss at the end of the loop before current execution catches up.
>
> return nr_events;
May be. We can experiment afterward and see if the numbers get better
--
Pavel Begunkov
next prev parent reply other threads:[~2021-09-28 9:36 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-24 20:59 [PATCH v2 00/24] rework and optimise submission+completion paths Pavel Begunkov
2021-09-24 20:59 ` [PATCH v2 01/24] io_uring: mark having different creds unlikely Pavel Begunkov
2021-09-24 20:59 ` [PATCH v2 02/24] io_uring: force_nonspin Pavel Begunkov
2021-09-24 20:59 ` [PATCH v2 03/24] io_uring: make io_do_iopoll return number of reqs Pavel Begunkov
2021-09-24 20:59 ` [PATCH v2 04/24] io_uring: use slist for completion batching Pavel Begunkov
2021-09-26 6:57 ` Hao Xu
2021-09-28 9:41 ` Pavel Begunkov
2021-09-28 15:32 ` Jens Axboe
2021-09-24 20:59 ` [PATCH v2 05/24] io_uring: remove allocation cache array Pavel Begunkov
2021-09-24 20:59 ` [PATCH v2 06/24] io-wq: add io_wq_work_node based stack Pavel Begunkov
2021-09-24 20:59 ` [PATCH v2 07/24] io_uring: replace list with stack for req caches Pavel Begunkov
2021-09-24 20:59 ` [PATCH v2 08/24] io_uring: split iopoll loop Pavel Begunkov
2021-09-24 20:59 ` [PATCH v2 09/24] io_uring: use single linked list for iopoll Pavel Begunkov
2021-09-24 20:59 ` [PATCH v2 10/24] io_uring: add a helper for batch free Pavel Begunkov
2021-09-26 3:36 ` Hao Xu
2021-09-28 9:33 ` Pavel Begunkov
2021-09-24 20:59 ` [PATCH v2 11/24] io_uring: convert iopoll_completed to store_release Pavel Begunkov
2021-09-24 20:59 ` [PATCH v2 12/24] io_uring: optimise batch completion Pavel Begunkov
[not found] ` <CAFUsyfLSXMvd_MBAp83qriW7LD=bg2=25TC4e_X4oMO1atoPYg@mail.gmail.com>
2021-09-28 9:35 ` Pavel Begunkov [this message]
2021-09-24 20:59 ` [PATCH v2 13/24] io_uring: inline completion batching helpers Pavel Begunkov
2021-09-24 20:59 ` [PATCH v2 14/24] io_uring: don't pass tail into io_free_batch_list Pavel Begunkov
2021-09-24 20:59 ` [PATCH v2 15/24] io_uring: don't pass state to io_submit_state_end Pavel Begunkov
2021-09-24 20:59 ` [PATCH v2 16/24] io_uring: deduplicate io_queue_sqe() call sites Pavel Begunkov
2021-09-24 20:59 ` [PATCH v2 17/24] io_uring: remove drain_active check from hot path Pavel Begunkov
2021-09-24 20:59 ` [PATCH v2 18/24] io_uring: split slow path from io_queue_sqe Pavel Begunkov
2021-09-24 20:59 ` [PATCH v2 19/24] io_uring: inline hot path of __io_queue_sqe() Pavel Begunkov
2021-09-24 21:00 ` [PATCH v2 20/24] io_uring: reshuffle queue_sqe completion handling Pavel Begunkov
2021-09-24 21:00 ` [PATCH v2 21/24] io_uring: restructure submit sqes to_submit checks Pavel Begunkov
2021-09-24 21:00 ` [PATCH v2 22/24] io_uring: kill off ->inflight_entry field Pavel Begunkov
2021-09-24 21:00 ` [PATCH v2 23/24] io_uring: comment why inline complete calls io_clean_op() Pavel Begunkov
2021-09-24 21:00 ` [PATCH v2 24/24] io_uring: disable draining earlier Pavel Begunkov
2021-09-30 16:04 ` [PATCH v2 00/24] rework and optimise submission+completion paths Jens Axboe
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