linux-kernel - [PATCH 6/6] cpumask: reduce cpumask

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Date:	Thu, 19 Nov 2009 19:31:36 +1030
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	linux-kernel@...r.kernel.org
Cc:	Ingo Molnar <mingo@...e.hu>, Mike Travis <travis@....com>
Subject: [PATCH 6/6] cpumask: reduce cpumask_size


Now we're sure noone is using old cpumask operators, nor *cpumask, we can
allocate less bits safely.  This reduces the memory usage of off-stack
cpumasks when CONFIG_CPUMASK_OFFSTACK=y but we don't have NR_CPUS actual
cpus.

Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
---
 include/linux/cpumask.h |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -1014,13 +1014,11 @@ static inline int cpulist_parse(const ch
 /**
  * cpumask_size - size to allocate for a 'struct cpumask' in bytes
  *
- * This will eventually be a runtime variable, depending on nr_cpu_ids.
+ * This can be a runtime variable, depending on nr_cpu_ids.
  */
 static inline size_t cpumask_size(void)
 {
-	/* FIXME: Once all cpumask assignments are eliminated, this
-	 * can be nr_cpumask_bits */
-	return BITS_TO_LONGS(NR_CPUS) * sizeof(long);
+	return BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long);
 }
 
 /*

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