From: Peter Zijlstra <[email protected]>
To: Jens Axboe <[email protected]>
Cc: Jann Horn <[email protected]>, io-uring <[email protected]>,
Glauber Costa <[email protected]>,
Pavel Begunkov <[email protected]>
Subject: Re: [PATCH 7/9] io_uring: add per-task callback handler
Date: Fri, 21 Feb 2020 17:23:54 +0100 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On Fri, Feb 21, 2020 at 06:49:16AM -0800, Jens Axboe wrote:
> > Jens, what exactly is the benefit of running this on every random
> > schedule() vs in io_cqring_wait() ? Or even, since io_cqring_wait() is
> > the very last thing the syscall does, task_work.
>
> I took a step back and I think we can just use the task work, which
> makes this a lot less complicated in terms of locking and schedule
> state. Ran some quick testing with the below and it works for me.
>
> I'm going to re-spin based on this and just dump the sched_work
> addition.
Aswesome, simpler is better.
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 81aa3959f326..413ac86d7882 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -3529,7 +3529,7 @@ static int __io_async_wake(struct io_kiocb *req, struct io_poll_iocb *poll,
> * the exit check will ultimately cancel these work items. Hence we
> * don't need to check here and handle it specifically.
> */
> - sched_work_add(tsk, &req->sched_work);
> + task_work_add(tsk, &req->sched_work, true);
> wake_up_process(tsk);
> return 1;
> }
> @@ -5367,9 +5367,9 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
> do {
> if (io_cqring_events(ctx, false) >= min_events)
> return 0;
> - if (!current->sched_work)
> + if (!current->task_works)
> break;
> - sched_work_run();
> + task_work_run();
> } while (1);
>
> if (sig) {
> @@ -5392,6 +5392,12 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
> TASK_INTERRUPTIBLE);
> if (io_should_wake(&iowq, false))
> break;
> + if (current->task_works) {
> + task_work_run();
> + if (io_should_wake(&iowq, false))
> + break;
> + continue;
> + }
if (current->task_works)
task_work_run();
if (io_should_wake(&iowq, false);
break;
doesn't work?
> schedule();
> if (signal_pending(current)) {
> ret = -EINTR;
Anyway, we need to be careful about the context where we call
task_work_run(), but afaict doing it here should be fine.
next prev parent reply other threads:[~2020-02-21 16:23 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-20 20:31 [PATCHSET 0/9] io_uring: use polled async retry Jens Axboe
2020-02-20 20:31 ` [PATCH 1/9] io_uring: consider any io_read/write -EAGAIN as final Jens Axboe
2020-02-20 20:31 ` [PATCH 2/9] io_uring: io_accept() should hold on to submit reference on retry Jens Axboe
2020-02-20 20:31 ` [PATCH 3/9] sched: move io-wq/workqueue worker sched in/out into helpers Jens Axboe
2020-02-20 20:31 ` [PATCH 4/9] task_work_run: don't take ->pi_lock unconditionally Jens Axboe
2020-02-20 20:31 ` [PATCH 5/9] kernel: abstract out task work helpers Jens Axboe
2020-02-20 21:07 ` Peter Zijlstra
2020-02-20 21:08 ` Jens Axboe
2020-02-20 20:31 ` [PATCH 6/9] sched: add a sched_work list Jens Axboe
2020-02-20 21:17 ` Peter Zijlstra
2020-02-20 21:53 ` Jens Axboe
2020-02-20 22:02 ` Jens Axboe
2020-02-20 20:31 ` [PATCH 7/9] io_uring: add per-task callback handler Jens Axboe
2020-02-20 22:02 ` Jann Horn
2020-02-20 22:14 ` Jens Axboe
2020-02-20 22:18 ` Jens Axboe
2020-02-20 22:25 ` Jann Horn
2020-02-20 22:23 ` Jens Axboe
2020-02-20 22:38 ` Jann Horn
2020-02-20 22:56 ` Jens Axboe
2020-02-20 22:58 ` Jann Horn
2020-02-20 23:02 ` Jens Axboe
2020-02-20 22:23 ` Jann Horn
2020-02-20 23:00 ` Jens Axboe
2020-02-20 23:12 ` Jann Horn
2020-02-20 23:22 ` Jens Axboe
2020-02-21 1:29 ` Jann Horn
2020-02-21 17:32 ` Jens Axboe
2020-02-21 19:24 ` Jann Horn
2020-02-21 20:18 ` Jens Axboe
2020-02-20 22:56 ` Jann Horn
2020-02-21 10:47 ` Peter Zijlstra
2020-02-21 14:49 ` Jens Axboe
2020-02-21 15:02 ` Jann Horn
2020-02-21 16:12 ` Peter Zijlstra
2020-02-21 16:23 ` Peter Zijlstra [this message]
2020-02-21 20:13 ` Jens Axboe
2020-02-21 13:51 ` Pavel Begunkov
2020-02-21 14:50 ` Jens Axboe
2020-02-21 18:30 ` Pavel Begunkov
2020-02-21 19:10 ` Jens Axboe
2020-02-21 19:22 ` Pavel Begunkov
2020-02-23 6:00 ` Jens Axboe
2020-02-23 6:26 ` Jens Axboe
2020-02-23 11:02 ` Pavel Begunkov
2020-02-23 14:49 ` Jens Axboe
2020-02-23 14:58 ` Jens Axboe
2020-02-23 15:07 ` Jens Axboe
2020-02-23 18:04 ` Pavel Begunkov
2020-02-23 18:06 ` Jens Axboe
2020-02-23 17:55 ` Pavel Begunkov
2020-02-20 20:31 ` [PATCH 8/9] io_uring: mark requests that we can do poll async in io_op_defs Jens Axboe
2020-02-20 20:31 ` [PATCH 9/9] io_uring: use poll driven retry for files that support it Jens Axboe
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