linux-kernel - Re: [PATCH] cpumask: alloc blank cpumask left over

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Date:	Fri, 05 Jun 2009 10:57:10 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Ingo Molnar <mingo@...e.hu>
CC:	Avi Kivity <avi@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cpumask: alloc blank cpumask left over

It seems we could remove that FIXME now.
cpumask_size is referred rather later.

Subject: [PATCH] use nr_cpumask_bits for cpumask_size calculating

so alloc_cpusmask_var could save some space when MAXSMP is used aka NR_CPUS
is 4096 on small conf system

Signed-off-by: Yinghai Lu <yinghai@...nel.org>

---
 include/linux/cpumask.h |    4 +---
 lib/cpumask.c           |    8 --------
 2 files changed, 1 insertion(+), 11 deletions(-)

Index: linux-2.6/include/linux/cpumask.h
===================================================================
--- linux-2.6.orig/include/linux/cpumask.h
+++ linux-2.6/include/linux/cpumask.h
@@ -996,9 +996,7 @@ static inline int cpulist_parse(const ch
  */
 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);
 }
 
 /*
Index: linux-2.6/lib/cpumask.c
===================================================================
--- linux-2.6.orig/lib/cpumask.c
+++ linux-2.6/lib/cpumask.c
@@ -100,14 +100,6 @@ bool alloc_cpumask_var_node(cpumask_var_
 		dump_stack();
 	}
 #endif
-	/* FIXME: Bandaid to save us from old primitives which go to NR_CPUS. */
-	if (*mask) {
-		unsigned char *ptr = (unsigned char *)cpumask_bits(*mask);
-		unsigned int tail;
-		tail = BITS_TO_LONGS(NR_CPUS - nr_cpumask_bits) * sizeof(long);
-		memset(ptr + cpumask_size() - tail, 0, tail);
-	}
-
 	return *mask != NULL;
 }
 EXPORT_SYMBOL(alloc_cpumask_var_node);
--
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