netdev - Re: [PATCH net-next v4 00/27] io

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Date:   Wed, 28 Sep 2022 13:31:37 -0600
From:   David Ahern <dsahern@...nel.org>
To:     Pavel Begunkov <asml.silence@...il.com>, io-uring@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        Willem de Bruijn <willemb@...gle.com>,
        Jens Axboe <axboe@...nel.dk>, kernel-team@...com
Subject: Re: [PATCH net-next v4 00/27] io_uring zerocopy send

On 9/26/22 1:08 PM, Pavel Begunkov wrote:
> Tried it out, the branch below fixes a small problem, adds a couple
> of extra optimisations and now it actually uses registered buffers.
> 
>     https://github.com/isilence/iperf iou-sendzc

thanks for the patch; will it pull it in.

> 
> Still, the submission loop looked a bit weird, i.e. it submits I/O
> to io_uring only when it exhausts sqes instead of sending right
> away with some notion of QD and/or sending in batches. The approach
> is good for batching (SQ size =16 here), but not so for latency.
> 
> I also see some CPU cycles being burnt in select(2). io_uring wait
> would be more natural and perhaps more performant, but I didn't
> spend enough time with iperf to say for sure.

ok. It will be a while before I have time to come back to it. In the
meantime it seems like some io_uring changes happened between your dev
branch and what was merged into liburing (compile worked on your branch
but fails with upstream). Is the ZC support in liburing now?