linux-kernel - Re: [PATCH v5 0/2] io_uring: Add support for napi_busy

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Message-ID: <47d2c632-b2c2-9736-01a6-bf1659be5299@kernel.dk>
Date:   Thu, 10 Mar 2022 06:36:33 -0700
From:   Jens Axboe <axboe@...nel.dk>
To:     Olivier Langlois <olivier@...llion01.com>,
        Pavel Begunkov <asml.silence@...il.com>
Cc:     Hao Xu <haoxu@...ux.alibaba.com>,
        io-uring <io-uring@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 0/2] io_uring: Add support for napi_busy_poll

On 3/8/22 3:17 PM, Olivier Langlois wrote:
> The sqpoll thread can be used for performing the napi busy poll in a
> similar way that it does io polling for file systems supporting direct
> access bypassing the page cache.
> 
> The other way that io_uring can be used for napi busy poll is by
> calling io_uring_enter() to get events.
> 
> If the user specify a timeout value, it is distributed between polling
> and sleeping by using the systemwide setting
> /proc/sys/net/core/busy_poll.
> 
> The changes have been tested with this program:
> https://github.com/lano1106/io_uring_udp_ping
> 
> and the result is:
> Without sqpoll:
> NAPI busy loop disabled:
> rtt min/avg/max/mdev = 40.631/42.050/58.667/1.547 us
> NAPI busy loop enabled:
> rtt min/avg/max/mdev = 30.619/31.753/61.433/1.456 us
> 
> With sqpoll:
> NAPI busy loop disabled:
> rtt min/avg/max/mdev = 42.087/44.438/59.508/1.533 us
> NAPI busy loop enabled:
> rtt min/avg/max/mdev = 35.779/37.347/52.201/0.924 us

Applied, thanks.

-- 
Jens Axboe