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Subject[tip:perf/core] perf_event: x86: Optimize the fast path a little more
Commit-ID:  c933c1a603d5bf700ddce79216c1be0ec3bc0e6c
Gitweb: http://git.kernel.org/tip/c933c1a603d5bf700ddce79216c1be0ec3bc0e6c
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Fri, 22 Jan 2010 16:40:12 +0100
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 29 Jan 2010 09:01:42 +0100

perf_event: x86: Optimize the fast path a little more

Remove num from the fast path and save a few ops.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
LKML-Reference: <20100122155536.056430539@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
arch/x86/kernel/cpu/perf_event.c | 6 +++---
1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 2c22ce4..33c889f 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1245,9 +1245,9 @@ 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, wmax;
struct event_constraint *c, *constraints[X86_PMC_IDX_MAX];
unsigned long used_mask[BITS_TO_LONGS(X86_PMC_IDX_MAX)];
+ int i, j, w, wmax, num = 0;
struct hw_perf_event *hwc;

bitmap_zero(used_mask, X86_PMC_IDX_MAX);
@@ -1260,7 +1260,7 @@ static int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign)
/*
* fastpath, try to reuse previous register
*/
- for (i = 0, num = n; i < n; i++, num--) {
+ for (i = 0; i < n; i++) {
hwc = &cpuc->event_list[i]->hw;
c = constraints[i];

@@ -1288,7 +1288,7 @@ static int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign)
if (assign)
assign[i] = hwc->idx;
}
- if (!num)
+ if (i == n)
goto done;

/*

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