perf: exclude_hv vs exclude_host in perf_event_attr

From: Vince Weaver
Date: Wed Dec 03 2014 - 09:17:46 EST



So what *is* the difference in perf_event_attr between
.exclude_hv
and
.exclude_guest
.exclude_host

>From what I gather .exclude_hv excluces hypervisor counts if the hardware
supports that type of measurement, but only Power implements this.

.exclude_guest and .exclude_host are x86 only? AMD does them in hardware
but it's implemented in software on Intel?
Do they only work when KVM is running, or do they tell you meaningful
stuff otherwise? What happens if I set them and KVM isn't running?

Also PEBS only will work if .exclude_guest is specified?


As always the code could use some commenting and the relevant commit
messages aren't really that stellar either.

Vince Weaver
vincent.weaver@xxxxxxxxx
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