From: Ulrich Drepper <drepper@gmail.com>
To: "Tomar, Nagendra" <nagendra_tomar@adaptec.com>
Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.arm.linux.org.uk
Subject: Re: Zeroed pages returned for heap
Date: Tue, 7 Jun 2005 01:53:19 -0700 [thread overview]
Message-ID: <a36005b505060701531a545ba4@mail.gmail.com> (raw)
In-Reply-To: <Pine.LNX.4.44.0506070936530.4569-100000@localhost.localdomain>
On 6/6/05, Nagendra Singh Tomar <nagendra_tomar@adaptec.com> wrote:
> Is it OK for an application (a C library implementing malloc/calloc is
> also an application) to assume that the pages returned by the OS for heap
> allocation (either directly thru brk() or thru mmap(MAP_ANONYMOUS)) will
> be zero filled.
The malloc code is glibc is defined with the assumption that brk
clears memory. Since this is what the kernel implements it would be a
horrible waste of time to reinitialize the memory. This behavior is
part of the kernel ABI and cannot be changed without breaking existing
applications without producing new libc DSOs (set MORECORE_CLEARS
appropriately) and relinking all statically linked apps.
next prev parent reply other threads:[~2005-06-07 8:53 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-06-07 4:23 Zeroed pages returned for heap Nagendra Singh Tomar
2005-06-07 8:53 ` Ulrich Drepper [this message]
2005-06-07 9:59 ` Nagendra Singh Tomar
2005-06-07 15:57 ` Peter Staubach
2005-06-08 4:08 ` Nagendra Singh Tomar
2005-06-09 10:14 ` Richard B. Johnson
2005-06-10 4:06 ` Nagendra Singh Tomar
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