From: Jens Axboe <[email protected]>
To: Peter Zijlstra <[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 12:13:42 -0800 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On 2/21/20 9:23 AM, Peter Zijlstra wrote:
> 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.
Agree!
>> @@ -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?
Yeah it totally does, I'll make that change. Not sure what I was
thinking there.
>> 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.
Right, that's the main win over the sched in/out approach. On clean
entry to a system call we should be fine, I added it for
io_uring_enter() as well. We're not holding anything at that point.
--
Jens Axboe
next prev parent reply other threads:[~2020-02-21 20:13 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
2020-02-21 20:13 ` Jens Axboe [this message]
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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