|Subject:||[Qemu-discuss] Guest has high iowait cpu usage but HV has no iowait|
|Date:||Mon, 6 Jul 2015 13:12:53 +0800|
I'm running a high I/O bound application in the KVM/QEMU VM, and I can see high %wa cpu usage in the guest.
%Cpu(s): 14.5 us, 11.3 sy, 0.0 ni, 36.2 id, 37.0 wa, 1.0 hi, 0.0 si, 0.0 st
But %wa in the HV is always 0.
%Cpu(s): 9.4 us, 1.5 sy, 0.0 ni, 89.0 id, 0.0 wa, 0.0 hi, 0.1 si, 0.0 st
My understanding is that VM's disk I/O is done by QEMU's I/O threads in HV, and running iostat in HV can also see heavy disk throughput, but why HV's %wa is 0 always ?
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