On 05/20/2010 02:05 PM, Stefan Hajnoczi wrote:
8330 kvm:kvm_entry # 0.000 M/sec
^--- count since starting perf
The 8330 number means that kvm_entry has fired 8330 times since perf
was started. Like Avi says, you need to keep the perf process
running. I run benchmarks using a script that kills perf after the
benchmark completes.
Jes, you're right, something like "perf stat -e kvm:* --start" and
"perf stat --stop" would be more usable for system-wide monitoring. I
wonder if it is possible to support this or whether the perf process
needs to periodically accumulate the counters (i.e. babysit the kernel
infrastructure)?
perf needs to be running to pull data out of the kernel (and since
profiling is tied to an fd life cycle).
What's wrong with starting perf after the warm-up period and stopping it
before it's done?
--
Do not meddle in the internals of kernels, for they are subtle and quick to
panic.
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