Am 10.02.2012 15:36, schrieb Dongsu Park:
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.
Hi,
I think I found the problem, there is no regression in the code.
I think the problem is, that qmeu-kvm with the IO-Thread enabled doesn't
produce enough cpu load to get the core to a higher cpu frequency,
because the load is distributed to two threads.
If I change the cpu governor to "performance" the result from the master
branch is better than from the v0.14.1 branch.
I get the same results on a serversystem without powermanagment activated.
@Dongsu Could you confirm those findings?
1. Test on i7 Laptop with Cpu governor "ondemand".
v0.14.1
bw=63492KB/s iops=15873
bw=63221KB/s iops=15805
v1.0
bw=36696KB/s iops=9173
bw=37404KB/s iops=9350
master
bw=36396KB/s iops=9099
bw=34182KB/s iops=8545
Change the Cpu governor to "performance"
master
bw=81756KB/s iops=20393
bw=81453KB/s iops=20257
2. Test on AMD Istanbul without powermanagement activated.
v0.14.1
bw=53167KB/s iops=13291
bw=61386KB/s iops=15346
v1.0
bw=43599KB/s iops=10899
bw=46288KB/s iops=11572
master
bw=60678KB/s iops=15169
bw=62733KB/s iops=15683
-martin
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