From owner-freebsd-current@FreeBSD.ORG  Thu Jan 10 10:04:13 2008
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
Delivered-To: freebsd-current@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 4CF1B16A418
	for <freebsd-current@freebsd.org>; Thu, 10 Jan 2008 10:04:13 +0000 (UTC)
	(envelope-from des@des.no)
Received: from tim.des.no (tim.des.no [194.63.250.121])
	by mx1.freebsd.org (Postfix) with ESMTP id D585013C467
	for <freebsd-current@freebsd.org>; Thu, 10 Jan 2008 10:04:12 +0000 (UTC)
	(envelope-from des@des.no)
Received: from tim.des.no (localhost [127.0.0.1])
	by spam.des.no (Postfix) with ESMTP id 2E8602089;
	Thu, 10 Jan 2008 11:04:04 +0100 (CET)
X-Spam-Tests: AWL
X-Spam-Learn: disabled
X-Spam-Score: -0.2/3.0
X-Spam-Checker-Version: SpamAssassin 3.2.3 (2007-08-08) on tim.des.no
Received: from ds4.des.no (des.no [80.203.243.180])
	by smtp.des.no (Postfix) with ESMTP id 005E12049;
	Thu, 10 Jan 2008 11:04:00 +0100 (CET)
Received: by ds4.des.no (Postfix, from userid 1001)
	id D043E8449F; Thu, 10 Jan 2008 11:04:00 +0100 (CET)
From: =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= <des@des.no>
To: Peter Schuller <peter.schuller@infidyne.com>
References: <15094.1199751424@critter.freebsd.dk>
	<200801080237.40379.peter.schuller@infidyne.com>
	<86tzlonozc.fsf@ds4.des.no>
	<200801091922.56670.peter.schuller@infidyne.com>
Date: Thu, 10 Jan 2008 11:04:00 +0100
In-Reply-To: <200801091922.56670.peter.schuller@infidyne.com> (Peter
	Schuller's message of "Wed\, 9 Jan 2008 19\:22\:47 +0100")
Message-ID: <863at6j8tr.fsf@ds4.des.no>
User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/22.1 (berkeley-unix)
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
Cc: Andrew Reilly <andrew-freebsd@areilly.bpc-users.org>,
	Peter Jeremy <peterjeremy@optushome.com.au>,
	Poul-Henning Kamp <phk@phk.freebsd.dk>, freebsd-current@freebsd.org,
	Igor Mozolevsky <igor@hybrid-lab.co.uk>,
	Kostik Belousov <kostikbel@gmail.com>
Subject: Re: sbrk(2) broken
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Discussions about the use of FreeBSD-current
	<freebsd-current.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>, 
	<mailto:freebsd-current-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-current>
List-Post: <mailto:freebsd-current@freebsd.org>
List-Help: <mailto:freebsd-current-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 10 Jan 2008 10:04:13 -0000

Peter Schuller <peter.schuller@infidyne.com> writes:
> Dag-Erling Sm=C3=B8rgrav <des@des.no> writes:
> > Actually, malloc(3) can use madvise(2) to notify the kernel that
> > arbitrary pages in the arena are unused and can be discarded.  The
> > current implementation will do so if the H option is specified.
> However, in this context it will likely only help partially since you sti=
ll
> need a full page to be free (and with a lot of programs many allocations =
will
> be significantly smaller than that, and I have to assume no real-life mal=
loc
> will align all allocations to pages, or the overhead would be extreme).

Page-aligning every allocation would be supremely stupid, and jemalloc
does so only for allocations larger than a page.

DES
--=20
Dag-Erling Sm=C3=B8rgrav - des@des.no