linux-kernel - [tip:perf/core] perf_event: x86: Optimize the fast path a little more

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Date:	Fri, 29 Jan 2010 09:28:50 GMT
From:	tip-bot for Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, eranian@...gle.com, hpa@...or.com,
	mingo@...hat.com, a.p.zijlstra@...llo.nl, tglx@...utronix.de,
	mingo@...e.hu
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@...llo.nl>
AuthorDate: Fri, 22 Jan 2010 16:40:12 +0100
Committer:  Ingo Molnar <mingo@...e.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@...llo.nl>
Cc: Stephane Eranian <eranian@...gle.com>
LKML-Reference: <20100122155536.056430539@...llo.nl>
Signed-off-by: Ingo Molnar <mingo@...e.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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