On Mon, Mar 5, 2012 at 4:13 PM, Martin Mailand <martin@xxxxxxxxxxxx> wrote: > Am 10.02.2012 15:36, schrieb Dongsu Park: > >> Recently I observed performance regression regarding virtio-blk, >> especially different IO bandwidths between qemu-kvm 0.14.1 and 1.0. >> So I want to share the benchmark results, and ask you what the reason >> would be. > > > > Hi, > I think I found the problem, there is no regression in the code. > I think the problem is, that qmeu-kvm with the IO-Thread enabled doesn't > produce enough cpu load to get the core to a higher cpu frequency, because > the load is distributed to two threads. > If I change the cpu governor to "performance" the result from the master > branch is better than from the v0.14.1 branch. > I get the same results on a serversystem without powermanagment activated. > > @Dongsu Could you confirm those findings? > > > 1. Test on i7 Laptop with Cpu governor "ondemand". > > v0.14.1 > bw=63492KB/s iops=15873 > bw=63221KB/s iops=15805 > > v1.0 > bw=36696KB/s iops=9173 > bw=37404KB/s iops=9350 > > master > bw=36396KB/s iops=9099 > bw=34182KB/s iops=8545 > > Change the Cpu governor to "performance" > master > bw=81756KB/s iops=20393 > bw=81453KB/s iops=20257 Interesting finding. Did you show the 0.14.1 results with "performance" governor? Stefan -- 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
