Commit a94cab23 authored May 10, 2015 by Andi Kleen Committed by Ingo Molnar Aug 04, 2015

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>

parent b1bf72d6

arch/x86/include/asm/tsc.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -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;

arch/x86/kernel/tsc.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -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