Re: [Xen-devel] Much difference between netperf results on every run

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 19/10/06 7:56 pm, "Andrew Theurer" <habanero@xxxxxxxxxx> wrote:

>> the throughput measured by netperf differs from time to time. The
>> changeset was xen-unstable.hg C/S 11760. This is observed when I
>> executed a netperf on DomU connecting to a netserver on Dom0 in the
>> same box. The observed throughput was between 185Mbps to 3854Mbps. I
>> have never seen such a difference on ia64.
> 
> I am also seeing this, but with not as much variability. Actually I am
> seeing significantly less throughput (1/6th) for dom0->domU then
> domU->dom0, and for dom0->domU, I am seeing +/- 15% variability. I am
> looking in to it, but so far I have not discovered anything.
> 
> So you know what cpus the domU and dom0 are using? You might try pinning the
> domains to cpus and see what happens.

Current suspicion is packet loss due to insufficient receive buffers. Try
specifying module option "netback.queue_length=100" in domain 0. We're
working on a proper fix for 3.0.3-1.

 -- Keir



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