On 11/15/2009 02:00 PM, Gordan Bobic wrote:
Dor Laor wrote:
On 11/14/2009 04:23 PM, Gordan Bobic wrote:
I just tried paravirtualized virtio block devices, and my tests show
that they are approximately 30% slower than emulated IDE devices. I'm
guessing this isn't normal. Is this a known issue or am I likely to have
mosconfigured something? I'm using 64-bit RHEL/CentOS 5 (both host and
guest).
Please try to change the io scheduler on the host to io scheduler, it
should boost your performance back.
I presume you mean the deadline io scheduler. I tried that (kernel
parameter elevator=deadline) and it made no measurable difference
compared to the cfq scheduler.
What version of kvm do you use? Is it rhel5.4?
Can you post the qemu cmdline and the perf test in the guest?
Lastly, do you use cache=wb on qemu? it's just a fun mode, we use
cache=off only.
Gordan
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