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perf/x86: Add ability to calculate TSC from perf sample timestamps

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For modern CPUs, perf clock is directly related to TSC.  TSC
can be calculated from perf clock and vice versa using a simple
calculation.  Two of the three componenets of that calculation
are already exported in struct perf_event_mmap_page.  This patch
exports the third.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1372425741-1676-3-git-send-email-adrian.hunter@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Adrian Hunter
2013-06-28 16:22:18 +03:00
committed by Ingo Molnar
parent 860f085b74
commit c73deb6aec
4 changed files with 33 additions and 2 deletions
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6
arch/x86/kernel/tsc.c
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@@ -89,6 +89,12 @@ int check_tsc_unstable(void)
}
EXPORT_SYMBOL_GPL(check_tsc_unstable);
int check_tsc_disabled(void)
{
return tsc_disabled;
}
EXPORT_SYMBOL_GPL(check_tsc_disabled);
#ifdef CONFIG_X86_TSC
int __init notsc_setup(char *str)
{