linux-kernel - [PATCH resend] Optimize relay_alloc_page_array() slightly by using vzalloc rather than vmalloc and memset

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Message-ID: <alpine.LNX.2.00.1011042132480.15349@swampdragon.chaosbits.net>
Date:	Thu, 4 Nov 2010 21:44:41 +0100 (CET)
From:	Jesper Juhl <jj@...osbits.net>
To:	linux-kernel@...r.kernel.org
cc:	relayfs-devel@...ts.sourceforge.net,
	Andrew Morton <akpm@...ux-foundation.org>,
	Tom Zanussi <zanussi@...ibm.com>,
	Tom Zanussi <tzanussi@...il.com>,
	Karim Yaghmour <karim@...rsys.com>,
	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
	Paul Mundt <lethal@...ux-sh.org>, Jens Axboe <axboe@...nel.dk>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH resend] Optimize relay_alloc_page_array() slightly by using
 vzalloc rather than vmalloc and memset

Hi (please CC me on replies since I'm not subscribed to lists other than lkml),

We can optimize kernel/relay.c::relay_alloc_page_array() slightly by using 
vzalloc. The patch makes these changes:

 - use vzalloc instead of vmalloc+memset.
 - remove redundant local variable 'array'.
 - declare local 'pa_size' as const.

Cuts down nicely on both source and object-code size.

Now I just need to find someone to actually merge it...


Signed-off-by: Jesper Juhl <jj@...osbits.net>
Acked-by: Pekka Enberg <penberg@...nel.org>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
---
 relay.c |   15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/kernel/relay.c b/kernel/relay.c
index c7cf397..859ea5a 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -70,17 +70,10 @@ static const struct vm_operations_struct relay_file_mmap_ops = {
  */
 static struct page **relay_alloc_page_array(unsigned int n_pages)
 {
-	struct page **array;
-	size_t pa_size = n_pages * sizeof(struct page *);
-
-	if (pa_size > PAGE_SIZE) {
-		array = vmalloc(pa_size);
-		if (array)
-			memset(array, 0, pa_size);
-	} else {
-		array = kzalloc(pa_size, GFP_KERNEL);
-	}
-	return array;
+	const size_t pa_size = n_pages * sizeof(struct page *);
+	if (pa_size > PAGE_SIZE)
+		return vzalloc(pa_size);
+	return kzalloc(pa_size, GFP_KERNEL);
 }
 
 /*



-- 
Jesper Juhl <jj@...osbits.net>             http://www.chaosbits.net/
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