Re: [RFC PATCH 0/4] Implement multiqueue virtio-net

Krishna Kumar2
2010-09-08T16:45:37Z

"Michael S. Tsirkin" <mst@redhat.com> wrote on 09/08/2010 01:40:11 PM:

>
_______________________________________________________________________________

> > UDP (#numtxqs=8)
> > N# BW1 BW2 (%) SD1 SD2 (%)
> > __________________________________________________________
> > 4 29836 56761 (90.24) 67 63 (-5.97)
> > 8 27666 63767 (130.48) 326 265 (-18.71)
> > 16 25452 60665 (138.35) 1396 1269 (-9.09)
> > 32 26172 63491 (142.59) 5617 4202 (-25.19)
> > 48 26146 64629 (147.18) 12813 9316 (-27.29)
> > 64 25575 65448 (155.90) 23063 16346 (-29.12)
> > 128 26454 63772 (141.06) 91054 85051 (-6.59)
> > __________________________________________________________
> > N#: Number of netperf sessions, 90 sec runs
> > BW1,SD1,RSD1: Bandwidth (sum across 2 runs in mbps), SD and Remote
> > SD for original code
> > BW2,SD2,RSD2: Bandwidth (sum across 2 runs in mbps), SD and Remote
> > SD for new code. e.g. BW2=40716 means average BW2 was
> > 20358 mbps.
> >
>
> What happens with a single netperf?
> host -> guest performance with TCP and small packet speed
> are also worth measuring.

Guest -> Host (single netperf):
I am getting a drop of almost 20%. I am trying to figure out
why.

Host -> guest (single netperf):
I am getting an improvement of almost 15%. Again - unexpected.

Guest -> Host TCP_RR: I get an average 7.4% increase in #packets
for runs upto 128 sessions. With fewer netperf (under 8), there
was a drop of 3-7% in #packets, but beyond that, the #packets
improved significantly to give an average improvement of 7.4%.

So it seems that fewer sessions is having negative effect for
some reason on the tx side. The code path in virtio-net has not
changed much, so the drop in some cases is quite unexpected.

Thanks,

- KK