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SubjectRe: [PATCH v3 1/3] perf: Use monotonic clock as a source for timestamps
On Tue, Nov 04, 2014 at 12:28:36AM +0000, Pawel Moll wrote:

> +int sysctl_perf_sample_time_clk_id = CLOCK_MONOTONIC;

const ?

> /*
> * perf samples are done in some very critical code paths (NMIs).
> * If they take too much CPU time, the system can lock up and not
> @@ -324,7 +326,7 @@ extern __weak const char *perf_pmu_name(void)
>
> static inline u64 perf_clock(void)
> {
> - return local_clock();
> + return ktime_get_mono_fast_ns();
> }

Do we maybe want to make it boot-time switchable back to local_clock for
people with bad systems and or backwards compat issues?

Everybody using Core2 and older will very much not want to have this
unless they've got a very good reason for wanting it.


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