From: Max Kellermann <[email protected]>
To: Pavel Begunkov <[email protected]>
Cc: Jens Axboe <[email protected]>,
[email protected], [email protected]
Subject: Re: [PATCH 0/8] Various io_uring micro-optimizations (reducing lock contention)
Date: Wed, 29 Jan 2025 20:43:44 +0100 [thread overview]
Message-ID: <CAKPOu+-0kT5PXt1WbEGJSC8=47pZDz311DHB7D920ZHuoXPvwQ@mail.gmail.com> (raw)
In-Reply-To: <[email protected]>
On Wed, Jan 29, 2025 at 8:30 PM Pavel Begunkov <[email protected]> wrote:
> It's great to see iowq getting some optimisations, but note that
> it wouldn't be fair comparing it to single threaded peers when
> you have a lot of iowq activity as it might be occupying multiple
> CPUs.
True. Fully loaded with the benchmark, I see 400%-600% CPU usage on my
process (30-40% of that being spinlock contention).
I wanted to explore how far I can get with a single (userspace)
thread, and leave the dirty thread-sync work to the kernel.
> It's wasteful unless you saturate it close to 100%, and then you
> usually have SQPOLL on a separate CPU than the user task submitting
> requests, and so it'd take some cache bouncing. It's not a silver
> bullet.
Of course, memory latency always bites us in the end. But this isn't
the endgame just yet, we still have a lot of potential for
optimizations.
prev parent reply other threads:[~2025-01-29 19:43 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-28 13:39 [PATCH 0/8] Various io_uring micro-optimizations (reducing lock contention) Max Kellermann
2025-01-28 13:39 ` [PATCH 1/8] io_uring/io-wq: eliminate redundant io_work_get_acct() calls Max Kellermann
2025-01-28 13:39 ` [PATCH 2/8] io_uring/io-wq: add io_worker.acct pointer Max Kellermann
2025-01-28 13:39 ` [PATCH 3/8] io_uring/io-wq: move worker lists to struct io_wq_acct Max Kellermann
2025-01-28 13:39 ` [PATCH 4/8] io_uring/io-wq: cache work->flags in variable Max Kellermann
2025-01-29 18:57 ` Pavel Begunkov
2025-01-29 19:11 ` Max Kellermann
2025-01-29 23:41 ` Pavel Begunkov
2025-01-30 5:36 ` Max Kellermann
2025-01-30 14:57 ` Jens Axboe
2025-01-31 14:06 ` Pavel Begunkov
2025-01-30 14:54 ` Jens Axboe
2025-01-28 13:39 ` [PATCH 5/8] io_uring/io-wq: do not use bogus hash value Max Kellermann
2025-01-28 13:39 ` [PATCH 6/8] io_uring/io-wq: pass io_wq to io_get_next_work() Max Kellermann
2025-01-28 13:39 ` [PATCH 7/8] io_uring: cache io_kiocb->flags in variable Max Kellermann
2025-01-29 19:11 ` Pavel Begunkov
2025-01-28 13:39 ` [PATCH 8/8] io_uring: skip redundant poll wakeups Max Kellermann
2025-01-31 13:54 ` Pavel Begunkov
2025-01-31 17:16 ` Max Kellermann
2025-01-31 17:25 ` Pavel Begunkov
2025-01-29 17:18 ` [PATCH 0/8] Various io_uring micro-optimizations (reducing lock contention) Jens Axboe
2025-01-29 17:39 ` Max Kellermann
2025-01-29 17:45 ` Jens Axboe
2025-01-29 18:01 ` Max Kellermann
2025-01-31 16:13 ` Jens Axboe
2025-02-01 15:25 ` Jens Axboe
2025-02-01 15:30 ` Max Kellermann
2025-02-01 15:38 ` Jens Axboe
2025-01-29 19:30 ` Pavel Begunkov
2025-01-29 19:43 ` Max Kellermann [this message]
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