Re: [PATCH v1 00/15] io_uring zero copy rx

Pavel Begunkov
2024-10-10T13:18:29Z

On 10/9/24 19:21, Pedro Tammela wrote:
> 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.

Let's see if kperf supports it or can be easily added, but since page
flipping requires heavy mmap amortisation, looks there are even
different sets of users the interfaces cover, in this sense comparing
to copy IMHO could be more interesting.

> 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.

--
Pavel Begunkov