On 06/15/2011 07:08 PM, David Ahern wrote:
> What does
> dmesg say about Perf?
[ 0.050995] Performance Events: Nehalem events, core PMU driver.
[ 0.051466] ... version: 1
[ 0.052998] ... bit width: 40
[ 0.053999] ... generic registers: 2
[ 0.054998] ... value mask: 000000ffffffffff
[ 0.055998] ... max period: 000000007fffffff
[ 0.057997] ... fixed-purpose events: 0
[ 0.058998] ... event mask: 0000000000000003
Well, it's not a Nehalem. Can you tweak the model/family (via -cpu
host) so it doesn't match a Nehalem and instead falls on the
architectural PMU?
Trial-and-error should work to find a good combo.
>
>> Also, the numbers for branches and branch-misses just seem wrong
>> compared to the same command run in the host as well as running
>> perf-stat in the host on the vcpu thread running openssl (with the vcpu
>> pinned to a pcpu).
>
> Could be due to the fact that the counter is running in host mode. Will
You mean when perf is run in the guest?
Yes - it's counting host events (mostly kvm.ko) as well as guest events.
> be fixed once the exclude_host/exclude_guest patch makes it in (and
> gains Intel support).
>
How does exclude_{host,_guest} help if the guest-side counters are low
-- by orders of magnitude?
It's probably the misidentification as Nehalem.
--
error compiling committee.c: too many arguments to function
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