linux-kernel - [tip:perfcounters/core] perf_counter: Optimize sched in/out of counters

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Date:	Wed, 20 May 2009 17:19:21 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, acme@...hat.com, paulus@...ba.org,
	hpa@...or.com, mingo@...hat.com, jkacur@...hat.com,
	a.p.zijlstra@...llo.nl, mtosatti@...hat.com, tglx@...utronix.de,
	cjashfor@...ux.vnet.ibm.com, mingo@...e.hu
Subject: [tip:perfcounters/core] perf_counter: Optimize sched in/out of counters

Commit-ID:  afedadf23a2c90f3ba0d963282cbe6a6be129494
Gitweb:     http://git.kernel.org/tip/afedadf23a2c90f3ba0d963282cbe6a6be129494
Author:     Peter Zijlstra <a.p.zijlstra@...llo.nl>
AuthorDate: Wed, 20 May 2009 12:21:22 +0200
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Wed, 20 May 2009 12:43:34 +0200

perf_counter: Optimize sched in/out of counters

Avoid a function call for !group counters by directly calling the counter
function.

[ Impact: micro-optimize the code ]

Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Corey Ashford <cjashfor@...ux.vnet.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Marcelo Tosatti <mtosatti@...hat.com>
Cc: John Kacur <jkacur@...hat.com>
LKML-Reference: <20090520102553.511933670@...llo.nl>
Signed-off-by: Ingo Molnar <mingo@...e.hu>


---
 kernel/perf_counter.c |   25 +++++++++++++++++++------
 1 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 473ed2c..69d4de8 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -826,8 +826,12 @@ void __perf_counter_sched_out(struct perf_counter_context *ctx,
 
 	perf_disable();
 	if (ctx->nr_active) {
-		list_for_each_entry(counter, &ctx->counter_list, list_entry)
-			group_sched_out(counter, cpuctx, ctx);
+		list_for_each_entry(counter, &ctx->counter_list, list_entry) {
+			if (counter != counter->group_leader)
+				counter_sched_out(counter, cpuctx, ctx);
+			else
+				group_sched_out(counter, cpuctx, ctx);
+		}
 	}
 	perf_enable();
  out:
@@ -903,8 +907,12 @@ __perf_counter_sched_in(struct perf_counter_context *ctx,
 		if (counter->cpu != -1 && counter->cpu != cpu)
 			continue;
 
-		if (group_can_go_on(counter, cpuctx, 1))
-			group_sched_in(counter, cpuctx, ctx, cpu);
+		if (counter != counter->group_leader)
+			counter_sched_in(counter, cpuctx, ctx, cpu);
+		else {
+			if (group_can_go_on(counter, cpuctx, 1))
+				group_sched_in(counter, cpuctx, ctx, cpu);
+		}
 
 		/*
 		 * If this pinned group hasn't been scheduled,
@@ -932,9 +940,14 @@ __perf_counter_sched_in(struct perf_counter_context *ctx,
 		if (counter->cpu != -1 && counter->cpu != cpu)
 			continue;
 
-		if (group_can_go_on(counter, cpuctx, can_add_hw)) {
-			if (group_sched_in(counter, cpuctx, ctx, cpu))
+		if (counter != counter->group_leader) {
+			if (counter_sched_in(counter, cpuctx, ctx, cpu))
 				can_add_hw = 0;
+		} else {
+			if (group_can_go_on(counter, cpuctx, can_add_hw)) {
+				if (group_sched_in(counter, cpuctx, ctx, cpu))
+					can_add_hw = 0;
+			}
 		}
 	}
 	perf_enable();
--
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