linux-kernel - [PATCH] lib/cpumask.c: Optimize __any_online

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Message-ID: <20120215123208.15623.73499.stgit@srivatsabhat.in.ibm.com>
Date:	Wed, 15 Feb 2012 18:05:14 +0530
From:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
To:	akpm@...ux-foundation.org
Cc:	kosaki.motohiro@...il.com, linux-kernel@...r.kernel.org,
	venki@...gle.com, rusty@...tcorp.com.au
Subject: [PATCH] lib/cpumask.c: Optimize __any_online_cpu() calculation

__any_online_cpu() uses a for loop at the moment.
Instead, use cpumask_* operations to speed it up.

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
---
Actually, the patch posted at https://lkml.org/lkml/2012/2/15/101 removed
the last user of any_online_cpu() (and hence __any_online_cpu()).
However, since this is an exported symbol, I refrained from removing this
function altogether.

 lib/cpumask.c |    8 +-------
 1 files changed, 1 insertions(+), 7 deletions(-)

diff --git a/lib/cpumask.c b/lib/cpumask.c
index af3e5817..b25f53d 100644
--- a/lib/cpumask.c
+++ b/lib/cpumask.c
@@ -28,13 +28,7 @@ EXPORT_SYMBOL(__next_cpu_nr);
 
 int __any_online_cpu(const cpumask_t *mask)
 {
-	int cpu;
-
-	for_each_cpu(cpu, mask) {
-		if (cpu_online(cpu))
-			break;
-	}
-	return cpu;
+	return cpumask_any_and(mask, cpu_online_mask);
 }
 EXPORT_SYMBOL(__any_online_cpu);
 

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