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| author | Adrian Hunter <adrian.hunter@intel.com> | 2013-06-28 15:22:18 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2013-07-23 12:17:45 +0200 |
| commit | c73deb6aecda2955716f31572516f09d930ef450 (patch) | |
| tree | 037f7945cb4289545d5ffbe9506e071a83d6c1a6 /arch/x86/kernel/tsc.c | |
| parent | perf: Fix broken union in 'struct perf_event_mmap_page' (diff) | |
| download | linux-c73deb6aecda2955716f31572516f09d930ef450.tar.xz linux-c73deb6aecda2955716f31572516f09d930ef450.zip | |
perf/x86: Add ability to calculate TSC from perf sample timestamps
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>
Diffstat (limited to 'arch/x86/kernel/tsc.c')
| -rw-r--r-- | arch/x86/kernel/tsc.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index 6ff49247edf8..930e5d48f560 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -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) { |