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Subject[tip:perf/core] perf_event: x86: Optimize constraint weight computation
Commit-ID:  272d30be622c9c6cbd514b1211ff359292001baa
Gitweb: http://git.kernel.org/tip/272d30be622c9c6cbd514b1211ff359292001baa
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Fri, 22 Jan 2010 16:32:17 +0100
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 29 Jan 2010 09:01:41 +0100

perf_event: x86: Optimize constraint weight computation

Add a weight member to the constraint structure and avoid recomputing the
weight at runtime.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
LKML-Reference: <20100122155535.963944926@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
arch/x86/kernel/cpu/perf_event.c | 9 +++++----
1 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 092ad56..2c22ce4 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -23,6 +23,7 @@
#include <linux/uaccess.h>
#include <linux/highmem.h>
#include <linux/cpu.h>
+#include <linux/bitops.h>

#include <asm/apic.h>
#include <asm/stacktrace.h>
@@ -76,6 +77,7 @@ struct event_constraint {
};
int code;
int cmask;
+ int weight;
};

struct cpu_hw_events {
@@ -95,6 +97,7 @@ struct cpu_hw_events {
{ .idxmsk64[0] = (n) }, \
.code = (c), \
.cmask = (m), \
+ .weight = HWEIGHT64((u64)(n)), \
}

#define INTEL_EVENT_CONSTRAINT(c, n) \
@@ -1242,8 +1245,7 @@ static inline int is_x86_event(struct perf_event *event)

static int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign)
{
- int i, j , w, num;
- int weight, wmax;
+ int i, j, w, num, wmax;
struct event_constraint *c, *constraints[X86_PMC_IDX_MAX];
unsigned long used_mask[BITS_TO_LONGS(X86_PMC_IDX_MAX)];
struct hw_perf_event *hwc;
@@ -1320,8 +1322,7 @@ static int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign)
c = constraints[i];
hwc = &cpuc->event_list[i]->hw;

- weight = bitmap_weight(c->idxmsk, X86_PMC_IDX_MAX);
- if (weight != w)
+ if (c->weight != w)
continue;

for_each_bit(j, c->idxmsk, X86_PMC_IDX_MAX) {

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