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由 Kan Liang 提交于
Implementing a new --smi-cost mode in perf stat to measure SMI cost. During the measurement, the /sys/device/cpu/freeze_on_smi will be set. The measurement can be done with one counter (unhalted core cycles), and two free running MSR counters (IA32_APERF and SMI_COUNT). In practice, the percentages of SMI core cycles should be more useful than absolute value. So the output will be the percentage of SMI core cycles and SMI#. metric_only will be set by default. SMI cycles% = (aperf - unhalted core cycles) / aperf Here is an example output. Performance counter stats for 'sudo echo ': SMI cycles% SMI# 0.1% 1 0.010858678 seconds time elapsed Users who wants to get the actual value can apply additional --no-metric-only. Signed-off-by: NKan Liang <Kan.liang@intel.com> Acked-by: NJiri Olsa <jolsa@kernel.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Kan Liang <kan.liang@intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Robert Elliott <elliott@hpe.com> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1495825538-5230-3-git-send-email-kan.liang@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
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