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SubjectRe: [PATCH 0/3]measure SMI cost
On Thu, Mar 23, 2017 at 11:25 AM,  <kan.liang@intel.com> wrote:
> From: Kan Liang <Kan.liang@intel.com>
>
> Currently, there is no way to measure the time cost in System management
> mode (SMM) by perf.
>
> Intel perfmon supports FREEZE_WHILE_SMM bit in IA32_DEBUGCTL. Once it sets,
> the PMU core counters will freeze on SMI handler. But it will not have an
> effect on free running counters. E.g. APERF counter.
> The cost of SMI can be measured by (aperf - cycles).
>
> A new sysfs entry /sys/device/cpu/freeze_on_smi is introduced to set
> FREEZE_WHILE_SMM bit in IA32_DEBUGCTL.
>
> A new --smi-cost mode in perf stat is implemented to measure the SMI cost
> by calculating cycles and aperf results. In practice, the percentages of
> SMI cycles should be more useful than absolute value. So the output will be
> the percentage of SMI cycles and SMI#.
>
You are talking about the percentage of what cycles?
Wallclock, unhalted_ref_cycles, unhalted_core_cycles?
I
> Here is an example output.
>
> Performance counter stats for 'sudo echo ':
>
> SMI cycles% SMI#
> 0.1% 1
>
> 0.010858678 seconds time elapsed
>
>
> Kan Liang (3):
> perf/x86: add sysfs entry to freeze counter on SMI
> tools lib api fs: Add sysfs__write_int function
> perf stat: Add support to measure SMI cost
>
> arch/x86/events/core.c | 10 +++++++
> arch/x86/events/intel/core.c | 48 ++++++++++++++++++++++++++++++++++
> arch/x86/events/perf_event.h | 3 +++
> arch/x86/include/asm/msr-index.h | 1 +
> tools/lib/api/fs/fs.c | 29 ++++++++++++++++++++
> tools/lib/api/fs/fs.h | 4 +++
> tools/perf/Documentation/perf-stat.txt | 9 +++++++
> tools/perf/builtin-stat.c | 48 ++++++++++++++++++++++++++++++++++
> tools/perf/util/stat-shadow.c | 33 +++++++++++++++++++++++
> tools/perf/util/stat.c | 2 ++
> tools/perf/util/stat.h | 2 ++
> 11 files changed, 189 insertions(+)
>
> --
> 2.7.4
>

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