linux-kernel - Re: [PATCH] Perf, AMD: Prefer kzalloc() over kmalloc()+memset() in amd_alloc

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Date:	Mon, 01 Nov 2010 18:55:13 +0100
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Jesper Juhl <jj@...osbits.net>
Cc:	linux-kernel@...r.kernel.org, Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...e.hu>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Stephane Eranian <eranian@...gle.com>,
	"robert.richter" <robert.richter@....com>,
	Andreas Herrmann <andreas.herrmann3@....com>,
	Borislav Petkov <bp@...64.org>
Subject: Re: [PATCH] Perf, AMD: Prefer kzalloc() over kmalloc()+memset() in
 amd_alloc_nb()

On Sat, 2010-10-30 at 21:06 +0200, Jesper Juhl wrote:
> Hi,
> 
> I believe this would be an improvement?
> 
> Prefer kzalloc() over kmalloc()+memset() in amd_alloc_nb().
> 
> 
> Signed-off-by: Jesper Juhl <jj@...osbits.net>
> ---


I've changed it to..

---
Subject: perf, amd: Use kmalloc_node(,__GFP_ZERO) for northbridge structure allocation
From: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Date: Mon Nov 01 18:52:05 CET 2010

Jasper suggested we use the zeroing capability of the allocators
instead of calling memset ourselves. Add node affinity while we're at
it.

Reported-by: Jesper Juhl <jj@...osbits.net>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
---
Index: linux-2.6/arch/x86/kernel/cpu/perf_event_amd.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/cpu/perf_event_amd.c
+++ linux-2.6/arch/x86/kernel/cpu/perf_event_amd.c
@@ -280,11 +280,10 @@ static struct amd_nb *amd_alloc_nb(int c
 	struct amd_nb *nb;
 	int i;
 
-	nb = kmalloc(sizeof(struct amd_nb), GFP_KERNEL);
+	nb = kmalloc_node(sizeof(struct amd_nb), GFP_KERNEL | __GFP_ZERO, nb_id);
 	if (!nb)
 		return NULL;
 
-	memset(nb, 0, sizeof(*nb));
 	nb->nb_id = nb_id;
 
 	/*

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