* Pekka Enberg <penberg@xxxxxxxxxx> wrote: > This series fixes QCOW locking issues and implements delayed metadata writeout. > This improves performance of writeout to QCOW2 images that don't have clusters > and L2 tables allocated on-disk. > > I tested the series by running > > mount -t ext4 /dev/vdb /mnt > dd if=/dev/zero of=/mnt/tmp > > in the guest multiple times for fresly generated QCOW2 image: > > dd if=/dev/zero of=fs.ext4 bs=1024k count=512 && mkfs.ext4 -F fs.ext4 && qemu-img convert -O qcow2 fs.ext4 fs.qcow2 > > which causes worst-case behavior for the current code. > > Before: > > [ seekwatcher: http://userweb.kernel.org/~penberg/kvm-qcow-delayed/kvm-qcow2-master.png ] > > 511229952 bytes (511 MB) copied, 19.906 s, 25.7 MB/s > 511229952 bytes (511 MB) copied, 20.3168 s, 25.2 MB/s > 511229952 bytes (511 MB) copied, 20.8078 s, 24.6 MB/s > 511229952 bytes (511 MB) copied, 21.0889 s, 24.2 MB/s > 511229952 bytes (511 MB) copied, 20.7833 s, 24.6 MB/s > 511229952 bytes (511 MB) copied, 20.7536 s, 24.6 MB/s > 511229952 bytes (511 MB) copied, 20.0312 s, 25.5 MB/s > > After: > > [ seekwatcher: http://userweb.kernel.org/~penberg/kvm-qcow-delayed/kvm-qcow2-delayed.png ] > > 511229952 bytes (511 MB) copied, 7.68312 s, 66.5 MB/s > 511229952 bytes (511 MB) copied, 7.54065 s, 67.8 MB/s > 511229952 bytes (511 MB) copied, 9.34749 s, 54.7 MB/s > 511229952 bytes (511 MB) copied, 9.2421 s, 55.3 MB/s > 511229952 bytes (511 MB) copied, 9.9364 s, 51.5 MB/s > 511229952 bytes (511 MB) copied, 10.0337 s, 51.0 MB/s > 511229952 bytes (511 MB) copied, 9.39502 s, 54.4 MB/s Just wondering, how does Qemu perform on the same system using the same image, with comparable settings? Thanks, Ingo -- 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
