Hi all,
I am trying to run some performance tests using libvirt 1.2.17. For these tests
it is necessary to set a specific affinity for the VCPUs of a running VM.
The problem is, that I noticed a significant performance drop in my metrics
when using 'vcpupin' from the virsh console instead of running 'taskset'
natively.
Specifically the methods I am comparing are
1. Using native shell
taskset -a -cp $MY_CPUSET $MY_DOMAIN_PID
2. Using virsh console (performance ~30% down)
for all $VCPUs
virsh vcpupin my_domain -cpulist $MY_CPUSET -vcpu $VCPU -live
virsh emulatorpin my_domain -cpulist $MY_CPUSET -live
It seems that the usage of 'vcpupin' causes a performance drop even if it is
run alongside 'taskset' on the same $CPU_SET
Functionally everything seems to be working when I check the '/proc/' filesystem
cat /proc/MY_DOMAIN_PID/*/status | grep Cpus_allowed_list
My questions are:
1. Has anybody else noticed this?
2. Is this expected based on the implementation details?
3. Is this a bug that is fixed in a newer libvirt version?
4. Is there a solution to this issue?
Thanks,
George Paraskevopoulos
Software Engineer (SDN/NFV), INTRACOM-TELECOM
+ 30 210 667 7689
<mailto:geo...@intracom-telecom.com> geo...@intracom-telecom.com
19.7 km Markopoulou Ave 19002 Peania, Athens, Greece
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