From: Jens Axboe <[email protected]>
To: Peter Zijlstra <[email protected]>
Cc: [email protected], [email protected],
Josef <[email protected]>, Oleg Nesterov <[email protected]>
Subject: Re: [PATCH 2/2] io_uring: use TWA_SIGNAL for task_work if the task isn't running
Date: Mon, 10 Aug 2020 14:25:48 -0600 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On 8/10/20 2:13 PM, Jens Axboe wrote:
>> Would it be clearer to write it like so perhaps?
>>
>> /*
>> * Optimization; when the task is RUNNING we can do with a
>> * cheaper TWA_RESUME notification because,... <reason goes
>> * here>. Otherwise do the more expensive, but always correct
>> * TWA_SIGNAL.
>> */
>> if (READ_ONCE(tsk->state) == TASK_RUNNING) {
>> __task_work_notify(tsk, TWA_RESUME);
>> if (READ_ONCE(tsk->state) == TASK_RUNNING)
>> return;
>> }
>> __task_work_notify(tsk, TWA_SIGNAL);
>> wake_up_process(tsk);
>
> Yeah that is easier to read, wasn't a huge fan of the loop since it's
> only a single retry kind of condition. I'll adopt this suggestion,
> thanks!
Re-write it a bit on top of that, just turning it into two separate
READ_ONCE, and added appropriate comments. For the SQPOLL case, the
wake_up_process() is enough, so we can clean up that if/else.
https://git.kernel.dk/cgit/linux-block/commit/?h=io_uring-5.9&id=49bc5c16483945982cf81b0109d7da7cd9ee55ed
--
Jens Axboe
next prev parent reply other threads:[~2020-08-10 20:25 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-08 18:34 [PATCHSET 0/2] io_uring: use TWA_SIGNAL more carefully Jens Axboe
2020-08-08 18:34 ` [PATCH 1/2] kernel: split task_work_add() into two separate helpers Jens Axboe
2020-08-10 11:37 ` peterz
2020-08-10 15:01 ` Jens Axboe
2020-08-10 15:28 ` peterz
2020-08-10 17:51 ` Jens Axboe
2020-08-10 19:53 ` Peter Zijlstra
2020-08-08 18:34 ` [PATCH 2/2] io_uring: use TWA_SIGNAL for task_work if the task isn't running Jens Axboe
2020-08-10 11:42 ` peterz
2020-08-10 15:02 ` Jens Axboe
2020-08-10 19:21 ` Jens Axboe
2020-08-10 20:12 ` Peter Zijlstra
2020-08-10 20:13 ` Jens Axboe
2020-08-10 20:25 ` Jens Axboe [this message]
2020-08-10 20:32 ` Peter Zijlstra
2020-08-10 20:35 ` Jens Axboe
2020-08-10 20:35 ` Jann Horn
2020-08-10 21:06 ` Jens Axboe
2020-08-10 21:10 ` Peter Zijlstra
2020-08-10 21:12 ` Jens Axboe
2020-08-10 21:26 ` Jann Horn
2020-08-10 21:28 ` Jens Axboe
2020-08-10 22:01 ` Jens Axboe
2020-08-10 22:41 ` Jann Horn
2020-08-11 1:25 ` Jens Axboe
2020-08-11 6:45 ` Oleg Nesterov
2020-08-11 6:56 ` Peter Zijlstra
2020-08-11 7:14 ` Oleg Nesterov
2020-08-11 7:26 ` Oleg Nesterov
2020-08-11 7:49 ` Peter Zijlstra
2020-08-11 7:45 ` Peter Zijlstra
2020-08-11 8:10 ` Oleg Nesterov
2020-08-11 13:06 ` Jens Axboe
2020-08-11 14:05 ` Oleg Nesterov
2020-08-11 14:12 ` Jens Axboe
2020-08-10 21:27 ` Jens Axboe
2020-08-10 20:16 ` Jens Axboe
2020-08-13 16:25 ` Sasha Levin
2020-08-19 23:57 ` Sasha Levin
2020-08-19 23:59 ` Jens Axboe
2020-08-20 0:02 ` Jens Axboe
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