netdev - Re: [PATCH v1 00/15] io

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Message-ID: <2b23d0ba-493b-48ba-beca-adc1d1e0be61@mojatatu.com>
Date: Wed, 9 Oct 2024 15:21:53 -0300
From: Pedro Tammela <pctammela@...atatu.com>
To: Mina Almasry <almasrymina@...gle.com>, David Wei <dw@...idwei.uk>
Cc: io-uring@...r.kernel.org, netdev@...r.kernel.org,
 Jens Axboe <axboe@...nel.dk>, Pavel Begunkov <asml.silence@...il.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jesper Dangaard Brouer <hawk@...nel.org>, David Ahern <dsahern@...nel.org>
Subject: Re: [PATCH v1 00/15] io_uring zero copy rx

On 09/10/2024 13:55, Mina Almasry wrote:
> [...]
> 
> If not, I would like to see a comparison between TCP RX zerocopy and
> this new io-uring zerocopy. For Google for example we use the TCP RX
> zerocopy, I would like to see perf numbers possibly motivating us to
> move to this new thing.
> 
> [1] https://lwn.net/Articles/752046/
> 

Hi!

 From my own testing, the TCP RX Zerocopy is quite heavy on the page 
unmapping side. Since the io_uring implementation is expected to be 
lighter (see patch 11), I would expect a simple comparison to show 
better numbers for io_uring.

To be fair to the existing implementation, it would then be needed to be 
paired with some 'real' computation, but that varies a lot. As we 
presented in netdevconf this year, HW-GRO eventually was the best option 
for us (no app changes, etc...) but still a case by case decision.