|
From: | Reeted |
Subject: | Re: [Qemu-devel] virtio-blk performance regression and qemu-kvm |
Date: | Tue, 06 Mar 2012 23:07:40 +0100 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:8.0) Gecko/20111124 Thunderbird/8.0 |
On 03/06/12 13:59, Stefan Hajnoczi wrote:
On Mon, Mar 5, 2012 at 4:44 PM, Martin Mailand<address@hidden> wrote:Am 05.03.2012 17:35, schrieb Stefan Hajnoczi: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=20257Interesting finding. Did you show the 0.14.1 results with "performance" governor?Hi Stefan, all results are with "ondemand" except the one where I changed it to "performance" Do you want a v0.14.1 test with the governor on "performance"?Yes, the reason why that would be interesting is because it allows us to put the performance gain with master+"performance" into perspective. We could see how much of a change we get.
Me too, I would be interested in seeing 0.14.1 being tested with performance governor so to compare it to master with performance governor, to make sure that this is not a regression.
BTW, I'll take the opportunity to say that 15.8 or 20.3 k IOPS are very low figures compared to what I'd instinctively expect from a paravirtualized block driver. There are now PCIe SSD cards that do 240 k IOPS (e.g. "OCZ RevoDrive 3 x2 max iops") which is 12-15 times higher, for something that has to go through a real driver and a real PCI-express bus, and can't use zero-copy techniques. The IOPS we can give to a VM is currently less than half that of a single SSD SATA drive (60 k IOPS or so, these days). That's why I consider this topic of virtio-blk performances very important. I hope there can be improvements in this sector...
Thanks for your time R.
[Prev in Thread] | Current Thread | [Next in Thread] |