From mboxrd@z Thu Jan 1 00:00:00 1970 From: INAKOSHI Hiroya Subject: Re: [FYI] Much difference between netperf results on every run Date: Fri, 27 Oct 2006 18:49:31 +0900 Message-ID: <4541D62B.9080102@jp.fujitsu.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Keir Fraser Cc: Andrew Theurer , xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org Hi, Andrew and Keir, sorry for the delayed response. 1/ The updated results shows that there is still a large (about +/-75%) deviation on netperf throughput even with vcpu-pin. 2/ The throughput was rather worse with queue_length=100 (but it was not significant in accordance with t-test.) Its deviation was still large. My expectation was that the throughput would be better with less packet loss and that its deviation would get smaller. Dom-0 to Dom-U Dom-U to Dom-0 ------------------------------------------------------ default queue_length 975.06(+/-5.11) 386.04(+/-292.30) queue_length=100 954.31(+/-3.03) 293.41(+/-180.94) (unit: Mbps) The Xen version was unstable C/S 11834. The number of vcpus is one for each Domains. Vcpu-pin is configured so that a logical processor is dedicated to each vcpu. For comparison, the results for ia64 with the same vcpu-pin configuration are below (Xen version: ia64-unstable C/S 11961.) Dom-0 to Dom-U Dom-U to Dom-0 ------------------------------------------------------ default queue_length 279.27(+/-5.78) 1444.7(+/-10.06) queue_length=100 278.37(+/-3.84) 1498.90(+/-12.02) (unit: Mbps) Regards, Hiroya Keir Fraser wrote: > On 19/10/06 7:56 pm, "Andrew Theurer" 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 > > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel > >