David Laight <David.Laight@xxxxxxxxxx> wrote on 21/08/2014 05:29:41 PM: > From: David Laight <David.Laight@xxxxxxxxxx> > To: Razya Ladelsky/Haifa/IBM@IBMIL, "Michael S. Tsirkin" <mst@xxxxxxxxxx> > Cc: "abel.gordon@xxxxxxxxx" <abel.gordon@xxxxxxxxx>, Alex Glikson/ > Haifa/IBM@IBMIL, Eran Raichstein/Haifa/IBM@IBMIL, Joel Nider/Haifa/ > IBM@IBMIL, "kvm@xxxxxxxxxxxxxxx" <kvm@xxxxxxxxxxxxxxx>, "linux- > kernel@xxxxxxxxxxxxxxx" <linux-kernel@xxxxxxxxxxxxxxx>, > "netdev@xxxxxxxxxxxxxxx" <netdev@xxxxxxxxxxxxxxx>, > "virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx" > <virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx>, Yossi Kuperman1/Haifa/IBM@IBMIL > Date: 21/08/2014 05:31 PM > Subject: RE: [PATCH] vhost: Add polling mode > > From: Razya Ladelsky > > "Michael S. Tsirkin" <mst@xxxxxxxxxx> wrote on 20/08/2014 01:57:10 PM: > > > > > > Results: > > > > > > > > Netperf, 1 vm: > > > > The polling patch improved throughput by ~33% (1516 MB/sec -> > 2046 MB/sec). > > > > Number of exits/sec decreased 6x. > > > > The same improvement was shown when I tested with 3 vms running netperf > > > > (4086 MB/sec -> 5545 MB/sec). > > > > > > > > filebench, 1 vm: > > > > ops/sec improved by 13% with the polling patch. Number of exits > > > > was reduced by 31%. > > > > The same experiment with 3 vms running filebench showed similar numbers. > > > > > > > > Signed-off-by: Razya Ladelsky <razya@xxxxxxxxxx> > > > > > > This really needs more thourough benchmarking report, including > > > system data. One good example for a related patch: > > > http://lwn.net/Articles/551179/ > > > though for virtualization, we need data about host as well, and if you > > > want to look at streaming benchmarks, you need to test different message > > > sizes and measure packet size. > > > > > > > Hi Michael, > > I have already tried running netperf with several message sizes: > > 64,128,256,512,600,800... > > But the results are inconsistent even in the baseline/unpatched > > configuration. > > For smaller msg sizes, I get consistent numbers. However, at some point, > > when I increase the msg size > > I get unstable results. For example, for a 512B msg, I get two scenarios: > > vm utilization 100%, vhost utilization 75%, throughput ~6300 > > vm utilization 80%, vhost utilization 13%, throughput ~9400 (line rate) > > > > I don't know why vhost is behaving that way for certain message sizes. > > Do you have any insight to why this is happening? > > Have you tried looking at the actual ethernet packet sizes. > It may well jump between using small packets (the size of the writes) > and full sized ones. I will check it, Thanks, Razya > > If you are trying to measure ethernet packet 'cost' you need to use UDP. > However that probably uses different code paths. > > David > > > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
