[tip:perf/core] perf, x86: Use ALTERNATIVE() to check for X86_FEATURE_PERFCTR_CORE
From: tip-bot for Robert Richter
Date: Tue Apr 19 2011 - 08:05:15 EST
Commit-ID: c8e5910edf8bbe2e5c6c35a4ef2a578cc7893b25
Gitweb: http://git.kernel.org/tip/c8e5910edf8bbe2e5c6c35a4ef2a578cc7893b25
Author: Robert Richter <robert.richter@xxxxxxx>
AuthorDate: Sat, 16 Apr 2011 02:27:55 +0200
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Tue, 19 Apr 2011 10:08:12 +0200
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@xxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1302913676-14352-4-git-send-email-robert.richter@xxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
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 eed3673a..224a84f 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)
--
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