linux-kernel - Re: [PATCH v2] NOMMU: fix malloc performance by adding uninitialized flag

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Date:	Tue, 13 Oct 2009 22:03:36 +0900
From:	Paul Mundt <lethal@...ux-sh.org>
To:	Mike Frysinger <vapier@...too.org>
Cc:	uclinux-dev@...inux.org, David Howells <dhowells@...hat.com>,
	David McCullough <davidm@...pgear.com>,
	Greg Ungerer <gerg@...inux.org>, linux-kernel@...r.kernel.org,
	uclinux-dist-devel@...ckfin.uclinux.org,
	Jie Zhang <jie.zhang@...log.com>, Robin Getz <rgetz@...log.com>
Subject: Re: [PATCH v2] NOMMU: fix malloc performance by adding uninitialized flag

On Tue, Oct 13, 2009 at 07:20:21AM -0400, Mike Frysinger wrote:
> From: Jie Zhang <jie.zhang@...log.com>
> 
> The NOMMU code currently clears all anonymous mmapped memory.  While this
> is what we want in the default case, all memory allocation from userspace
> under NOMMU has to go through this interface, including malloc() which is
> allowed to return uninitialized memory.  This can easily be a significant
> performance penalty.  So for constrained embedded systems were security is
> irrelevant, allow people to avoid clearing memory unnecessarily.
> 
> This also alters the ELF-FDPIC binfmt such that it obtains uninitialised
> memory for the brk and stack region.
> 
> Signed-off-by: Jie Zhang <jie.zhang@...log.com>
> Signed-off-by: Robin Getz <rgetz@...log.com>
> Signed-off-by: Mike Frysinger <vapier@...too.org>
> Signed-off-by: David Howells <dhowells@...hat.com>

Acked-by: Paul Mundt <lethal@...ux-sh.org>
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