Am 06.03.2012 13:59, schrieb Stefan Hajnoczi:
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.
Does the CPU governor also affect the result when you benchmark with
real disks instead of ramdisk? I can see how the governor would
affect ramdisk, but would expect real disk I/O to be impacted much
less.
Hi,
here my results.
I tested with "fio -name iops -rw=read -size=1G -iodepth 1 -filename
/dev/vdb -ioengine libaio -direct 1 -bs 4k"
The qemu command was.
qemu-system-x86_64 --enable-kvm -m 512 -boot c \
-drive file=/home/martin/vmware/bisect_kvm/hda.img,cache=none,if=virtio
-drive file=/dev/ram0,cache=none,if=virtio
-drive file=/dev/sda2,cache=none,if=virtio
Host Kernel 3.3.0+rc4
Guest Kernel 3.0.0-16-generic ubuntu kernel
On the host I use a raw partition sda2 for the disk test, in qemu I
write with fio to /dev/vdc, though there is no fs involved.
The host disk can at max. 13K iops, in qemu I get at max 6,5K iops,
that's around about 50% overhead. All the test were with 4k reads, so I
think we are mostly latency bound.
-martin
log:
** v0.14.1 ondemand **
ram
bw=61038KB/s iops=15259
bw=66190KB/s iops=16547
disk
bw=18105KB/s iops=4526
bw=17625KB/s iops=4406
** v0.14.1 performance **
ram
bw=72356KB/s iops=18088
bw=72390KB/s iops=18097
disk
bw=27886KB/s iops=6971
bw=27915KB/s iops=6978
** master ondemand **
ram
bw=24833KB/s iops=6208
bw=27275KB/s iops=6818
disk
bw=14980KB/s iops=3745
bw=14881KB/s iops=3720
** master performance **
ram
bw=64318KB/s iops=16079
bw=63523KB/s iops=15880
disk
bw=27043KB/s iops=6760
bw=27211KB/s iops=6802
Host Disk Test (SanDisk SSD U100)
host disk ondemand
bw=48823KB/s iops=12205
bw=49086KB/s iops=12271
host disk performance
bw=55156KB/s iops=13789
bw=54980KB/s iops=13744
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