linux-kernel - Re: [patch 2/3] MAP_NOZERO

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Date:	Tue, 26 Jun 2007 22:04:11 -0700
From:	"Ulrich Drepper" <drepper@...il.com>
To:	"Rik van Riel" <riel@...hat.com>
Cc:	"Davide Libenzi" <davidel@...ilserver.org>,
	"Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>
Subject: Re: [patch 2/3] MAP_NOZERO - implement sys_brk2()

On 6/26/07, Rik van Riel <riel@...hat.com> wrote:
> After going through the first malloc()/free() cycle, surely
> the memory will no longer be zeroed on the second malloc() ?

If returned to the system, sure.

> What makes the first brk malloc so special?

If the memory is zeroed it needs not be initialized by malloc.  No
calloc zeroing, no pointer clearing.

Anyway, it's irrelevant what the benefits are, the fact is current
code depends on brk to zero the memory and you'd break the ABI if
you'd change it.
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