diff options
| author | Yan, Zheng <zheng.z.yan@intel.com> | 2015-05-06 15:33:47 -0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-06-07 16:08:35 +0200 |
| commit | 851559e35fd5ab637783ba395e55edd50f761229 (patch) | |
| tree | 7472cbc458ca562db11236e8d53bc06e82998d96 /arch/x86/kernel/cpu/perf_event.h | |
| parent | 5b68164d6a1fdbe02b30bd777d1f686c6d901f28 (diff) | |
| download | linux-rt-851559e35fd5ab637783ba395e55edd50f761229.tar.gz | |
perf/x86/intel: Use the PEBS auto reload mechanism when possible
When a fixed period is specified, this patch makes perf use the PEBS
auto reload mechanism. This makes normal profiling faster, because
it avoids one costly MSR write in the PMI handler.
However, the reset value will be loaded by hardware assist. There is a
small delay compared to the previous non-auto-reload mechanism. The
delay time is arbitrary, but very small. The assist cost is 400-800
cycles, assuming common cases with everything cached. The minimum period
the patch currently uses is 10000. In that extreme case it can be ~10%
if cycles are used.
Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Signed-off-by: Kan Liang <kan.liang@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: acme@infradead.org
Cc: eranian@google.com
Link: http://lkml.kernel.org/r/1430940834-8964-2-git-send-email-kan.liang@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/cpu/perf_event.h')
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h index 89e6cd61e6ae..7a3f0fdd2fbd 100644 --- a/arch/x86/kernel/cpu/perf_event.h +++ b/arch/x86/kernel/cpu/perf_event.h @@ -75,6 +75,7 @@ struct event_constraint { #define PERF_X86_EVENT_DYNAMIC 0x0080 /* dynamic alloc'd constraint */ #define PERF_X86_EVENT_RDPMC_ALLOWED 0x0100 /* grant rdpmc permission */ #define PERF_X86_EVENT_EXCL_ACCT 0x0200 /* accounted EXCL event */ +#define PERF_X86_EVENT_AUTO_RELOAD 0x0400 /* use PEBS auto-reload */ struct amd_nb { |