diff options
| author | Robert Richter <robert.richter@amd.com> | 2011-04-16 02:27:55 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2011-04-19 10:08:12 +0200 |
| commit | c8e5910edf8bbe2e5c6c35a4ef2a578cc7893b25 (patch) | |
| tree | fa9b4676c4cd01577653941216301cccfb5b52a3 | |
| parent | 68d2cf25d39324c54b5e42de7915c623a0917abe (diff) | |
perf, x86: Use ALTERNATIVE() to check for X86_FEATURE_PERFCTR_CORE
Using ALTERNATIVE() when checking for X86_FEATURE_PERFCTR_CORE avoids
an extra pointer chase and data cache hit.
Signed-off-by: Robert Richter <robert.richter@amd.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1302913676-14352-4-git-send-email-robert.richter@amd.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event.c | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index eed3673a865..224a84f7080 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -31,6 +31,7 @@ #include <asm/nmi.h> #include <asm/compat.h> #include <asm/smp.h> +#include <asm/alternative.h> #if 0 #undef wrmsrl @@ -363,12 +364,18 @@ again: return new_raw_count; } -/* using X86_FEATURE_PERFCTR_CORE to later implement ALTERNATIVE() here */ static inline int x86_pmu_addr_offset(int index) { - if (boot_cpu_has(X86_FEATURE_PERFCTR_CORE)) - return index << 1; - return index; + int offset; + + /* offset = X86_FEATURE_PERFCTR_CORE ? index << 1 : index */ + alternative_io(ASM_NOP2, + "shll $1, %%eax", + X86_FEATURE_PERFCTR_CORE, + "=a" (offset), + "a" (index)); + + return offset; } static inline unsigned int x86_pmu_config_addr(int index) |