Re: [PATCH v1 00/15] zero-copy RX for io_uring

Jonathan Lemon
2022-11-09T15:27:11Z

On Wed, Nov 09, 2022 at 02:37:42PM +0800, Dust Li wrote:
>
> Haven't dive into your test case yet, but the performance data
> looks disappointing
>
> I don't know why we need zerocopy if we can't get a big performance
> gain.

The cited numbers are intended to show that there is no network
bandwidth performance drop from using RECV_ZC. For the systems under
test (25Gb, 50Gb), we are getting linerate already, so there wouldn't be
any BW improvement.

The zerocopy gains come from a reduction in memory bandwith, removing
the user memcpy overhead, reducing the CPU usage. This is why I put up
the changes for iperf3, so cpu and membw usage metrics can be collected
while under network load.

> Have you tested large messages with jumbo or LRO enabled ?

Haven't tested jumbo frames, but these are with GRO support.
--
Jonathan