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

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Message-ID: <cde6d338-880b-57c7-d9e5-86d117647e8d@kernel.dk>
Date:   Wed, 9 Mar 2022 16:44:03 -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 10:47 PM, Olivier Langlois wrote:
> On Tue, 2022-03-08 at 17:54 -0700, Jens Axboe wrote:
>> 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.
>>
>> I think we should get this queued up, but it doesn't apply to
>> for-5.18/io_uring at all. I can fix it up, but just curious what you
>> tested against?
>>
> Hi Jens,
> 
> I did wrote the patch from
> git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> 
> My testing systems are based on 5.16. I have backported the patch and
> compiled 5.16.12 with the patch for my testing.
> 
> sorry if I didn't use the right repo...

Generally, since the patch is for 5.18, you'd want to base it on my
for-5.18/io_uring branch as then it would apply on top of what is
already pending. But I'll see if I can shoe horn it, unfortunately we'll
hit a merge error but it'll be minor.

-- 
Jens Axboe