On Wed, Mar 7, 2012 at 2:21 PM, Reeted <reeted@xxxxxxxxxxxxx> wrote: > On 03/07/12 09:04, Stefan Hajnoczi wrote: >> >> On Tue, Mar 6, 2012 at 10:07 PM, Reeted<reeted@xxxxxxxxxxxxx> wrote: >>> >>> On 03/06/12 13:59, Stefan Hajnoczi wrote: >>>> >>>> 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... >> >> It depends on the benchmark configuration. virtio-blk is capable of >> doing 100,000s of iops, I've seen results. My guess is that you can >> do>100,000 read iops with virtio-blk on a good machine and stock >> qemu-kvm. > > > It's very difficult to configure, then. > I also did benchmarks in the past, and I can confirm Martin and Dongsu > findings of about 15 k IOPS with: > qemu-kvm 0.14.1, Intel Westmere CPU, virtio-blk (kernel 2.6.38 on the guest, > 3.0 on the host), fio, 4k random *reads* from the Host page cache (backend > LVM device was fully in cache on the Host), writeback setting, cache dropped > on the guest prior to benchmark (and insufficient guest memory to cache a > significant portion of the device). > If you can teach us how to reach 100 k IOPS, I think everyone would be > grateful :-) Sorry for being vague, I don't have the details. I have CCed Khoa, who might have time to describe a >100,000 iops virtio-blk configuration. 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
