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perf/x86: Add a native_perf_sched_clock_from_tsc() 

PEBSv3 has a raw TSC time stamp in its memory buffer that
later needs to to be converted to perf_clock.

Add a native_sched_clock_from_tsc() that works the same
as native_sched_clock(), but starts with an already given
TSC value.

Paravirt is ignored, it will just get the native clock.
But there isn't a para virtualized PEBS anyway.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: eranian@google.com
Link: http://lkml.kernel.org/r/1431285767-27027-2-git-send-email-andi@firstfloor.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
hifive-unleashed-5.1
Andi Kleen 2015-05-10 12:22:39 -07:00 committed by Ingo Molnar
parent b1bf72d669
commit a94cab2376
2 changed files with 9 additions and 0 deletions
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1
arch/x86/include/asm/tsc.h
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@ -51,6 +51,7 @@ extern int unsynchronized_tsc(void);
extern int check_tsc_unstable(void);
extern int check_tsc_disabled(void);
extern unsigned long native_calibrate_tsc(void);
extern unsigned long long native_sched_clock_from_tsc(u64 tsc);
extern int tsc_clocksource_reliable;

8
arch/x86/kernel/tsc.c
View File

@ -296,6 +296,14 @@ u64 native_sched_clock(void)
return cycles_2_ns(tsc_now);
}
/*
* Generate a sched_clock if you already have a TSC value.
*/
u64 native_sched_clock_from_tsc(u64 tsc)
{
return cycles_2_ns(tsc);
}
/* We need to define a real function for sched_clock, to override the
weak default version */
#ifdef CONFIG_PARAVIRT