linux-kernel - Re: [PATCH] io_uring: wakeup threads waiting for EPOLLOUT events

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Message-ID: <2d2dda92-3c50-ee62-5ffe-0589d4c8fc0d@kernel.dk>
Date:   Thu, 16 Jan 2020 08:29:07 -0700
From:   Jens Axboe <axboe@...nel.dk>
To:     Stefano Garzarella <sgarzare@...hat.com>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH] io_uring: wakeup threads waiting for EPOLLOUT events

On 1/16/20 6:49 AM, Stefano Garzarella wrote:
> io_uring_poll() sets EPOLLOUT flag if there is space in the
> SQ ring, then we should wakeup threads waiting for EPOLLOUT
> events when we expose the new SQ head to the userspace.
> 
> Signed-off-by: Stefano Garzarella <sgarzare@...hat.com>
> ---
> 
> Do you think is better to change the name of 'cq_wait' and 'cq_fasync'?

I honestly think it'd be better to have separate waits for in/out poll,
the below patch will introduce some unfortunate cacheline traffic
between the submitter and completer side.

-- 
Jens Axboe