On 05/20/2010 02:23 PM, Stefan Hajnoczi wrote:
On Thu, May 20, 2010 at 12:16 PM, Jes Sorensen<Jes.Sorensen@xxxxxxxxxx> wrote:
On 05/20/10 13:10, Avi Kivity wrote:
What's wrong with starting perf after the warm-up period and stopping it
before it's done?
It's pretty hard to script.
I use the following. It ain't pretty:
#!/bin/bash
cleanup() {
trap - 2
kill -2 $sleep_pid
echo 0>/sys/kernel/debug/tracing/events/kvm/enable
kill $cat_pid
}
perf stat -a -e 'kvm:*' sleep 1h>results/perf_stat 2>&1&
sleep_pid=$(sleep 1&& pgrep -x -f "sleep 1h") # sleep 1 is to avoid
race with forked perf process
trap cleanup 2
echo 1>/sys/kernel/debug/tracing/events/kvm/enable
cat /sys/kernel/debug/tracing/trace_pipe>results/trace&
cat_pid=$!
# ...do stuff here...
cleanup
perf will enable the events by itself (no?), so all you need is is the
perf call in the middle.
What's missing is vmstat-like or kvm_stat-like output, but that's
another thing.
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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