On Sun, Nov 16, 2014 at 02:08:49PM +0200, Razya Ladelsky wrote: > Razya Ladelsky/Haifa/IBM@IBMIL wrote on 29/10/2014 02:38:31 PM: > > > From: Razya Ladelsky/Haifa/IBM@IBMIL > > To: mst@xxxxxxxxxx > > Cc: Razya Ladelsky/Haifa/IBM@IBMIL, Alex Glikson/Haifa/IBM@IBMIL, > > Eran Raichstein/Haifa/IBM@IBMIL, Yossi Kuperman1/Haifa/IBM@IBMIL, > > Joel Nider/Haifa/IBM@IBMIL, abel.gordon@xxxxxxxxx, kvm@xxxxxxxxxxxxxxx > > Date: 29/10/2014 02:38 PM > > Subject: Benchmarking for vhost polling patch > > > > Hi Michael, > > > > Following the polling patch thread: http://marc.info/? > > l=kvm&m=140853271510179&w=2, > > I changed poll_stop_idle to be counted in micro seconds, and carried out > > > experiments using varying sizes of this value. > > > > If it makes sense to you, I will continue with the other changes > > requested for > > the patch. > > > > Thank you, > > Razya > > > > > > Dear Michael, > I'm still interested in hearing your opinion about these numbers > http://marc.info/?l=kvm&m=141458631532669&w=2, > and whether it is worthwhile to continue with the polling patch. > Thank you, > Razya > > > > > > Hi Razya, On the netperf benchmark, it looks like polling=10 gives a modest but measureable gain. So from that perspective it might be worth it if it's not too much code, though we'll need to spend more time checking the macro effect - we barely moved the needle on the macro benchmark and that is suspicious. Is there a chance you are actually trading latency for throughput? do you observe any effect on latency? How about trying some other benchmark, e.g. NFS? Also, I am wondering: since vhost thread is polling in kernel anyway, shouldn't we try and poll the host NIC? that would likely reduce at least the latency significantly, won't it? -- MST -- 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
