linux-kernel - [PATCH] cpusets: Allocate heap only when required

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Date:	Thu, 23 Jan 2014 16:45:34 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	mingo@...nel.org, peterz@...radead.org
Cc:	linaro-kernel@...ts.linaro.org, patches@...aro.org,
	linux-kernel@...r.kernel.org,
	Viresh Kumar <viresh.kumar@...aro.org>
Subject: [PATCH] cpusets: Allocate heap only when required

update_flag() routine uses heap only when spread_flag_changed is true. Otherwise
heap isn't used, but is allocated and freed unnecessarily.

Fix this by allocating heap only when required.

Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
Rebased over linux-next/master

 kernel/cpuset.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 4410ac6..9ccdfb2 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1326,16 +1326,18 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
 	if (err < 0)
 		goto out;
 
-	err = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
-	if (err < 0)
-		goto out;
-
 	balance_flag_changed = (is_sched_load_balance(cs) !=
 				is_sched_load_balance(trialcs));
 
 	spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs))
 			|| (is_spread_page(cs) != is_spread_page(trialcs)));
 
+	if (spread_flag_changed) {
+		err = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
+		if (err < 0)
+			goto out;
+	}
+
 	mutex_lock(&callback_mutex);
 	cs->flags = trialcs->flags;
 	mutex_unlock(&callback_mutex);
@@ -1343,9 +1345,10 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
 	if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
 		rebuild_sched_domains_locked();
 
-	if (spread_flag_changed)
+	if (spread_flag_changed) {
 		update_tasks_flags(cs, &heap);
-	heap_free(&heap);
+		heap_free(&heap);
+	}
 out:
 	free_trial_cpuset(trialcs);
 	return err;
-- 
1.7.12.rc2.18.g61b472e

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