On 10/9/24 10:53 AM, Jens Axboe wrote: > On 10/9/24 10:50 AM, Jens Axboe wrote: >> On 10/9/24 10:35 AM, David Ahern wrote: >>> On 10/9/24 9:43 AM, Jens Axboe wrote: >>>> Yep basically line rate, I get 97-98Gbps. I originally used a slower box >>>> as the sender, but then you're capped on the non-zc sender being too >>>> slow. The intel box does better, but it's still basically maxing out the >>>> sender at this point. So yeah, with a faster (or more efficient sender), >>> >>> I am surprised by this comment. You should not see a Tx limited test >>> (including CPU bound sender). Tx with ZC has been the easy option for a >>> while now. >> >> I just set this up to test yesterday and just used default! I'm sure >> there is a zc option, just not the default and hence it wasn't used. >> I'll give it a spin, will be useful for 200G testing. > > I think we're talking past each other. Yes send with zerocopy is > available for a while now, both with io_uring and just sendmsg(), but > I'm using kperf for testing and it does not look like it supports it. > Might have to add it... We'll see how far I can get without it. Stanislav pointed me at: https://github.com/facebookexperimental/kperf/pull/2 which adds zc send. I ran a quick test, and it does reduce cpu utilization on the sender from 100% to 95%. I'll keep poking... -- Jens Axboe
