On Fri, 10 Feb 2012 15:36:39 +0100, Dongsu Park <dongsu.p...@profitbricks.com> wrote: > Hi, > > 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.
Interesting. There are two obvious possibilities here. One is that qemu has regressed, the other is that virtio_blk has regressed; the new qemu may negotiate new features. Please do the following in the guest with old and new qemus: cat /sys/class/block/vdb/device/features (eg, here that gives: 0010101101100000000000000000100e0). Thanks, Rusty.
