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Re: [libvirt] [PATCH] Refresh QEMU driver caps in getCapabilities



Cole Robinson schrieb:
(...)

To test the performance impact, I used a simple python script:

import libvirt
conn = libvirt.open("qemu:///system")
for i in range(0, 30):
    conn.getCapabilities()

The time difference was on average .02 seconds slower, which I think is
negligible.

If at somepoint in the future, capabilities generation becomes smarter
(searching PATH emulators, scraping device list output, etc.) it might
be worth re-checking the time impact. But for now it doesn't seem to be
an issue.

Thanks,
Cole
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.02 seconds slower compared to what time?
Without a given base this result doesn't say much.
It wouldn't matter if the execution-time was 3600 seconds prior to the change but would be a realt bottleneck if it was 0.01 seconds prior to the change. I know a virsh capabilities is not that slow, but i haven't clocked it up to now but have done so now that i have read your post and got this on my machine:

rr016# time virsh capabilities
(...)
real    0m0.005s
user    0m0.001s
sys     0m0.002s

So the change would mean a 300% penalty. I could live with that because even with .02 seconds it is fast.

Gerrit


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