From owner-freebsd-questions@FreeBSD.ORG Thu Sep 14 08:55:54 2006 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 9178B16A407 for ; Thu, 14 Sep 2006 08:55:54 +0000 (UTC) (envelope-from m.seaman@infracaninophile.co.uk) Received: from smtp.infracaninophile.co.uk (ns0.infracaninophile.co.uk [81.187.76.162]) by mx1.FreeBSD.org (Postfix) with ESMTP id ECB7D43D46 for ; Thu, 14 Sep 2006 08:55:52 +0000 (GMT) (envelope-from m.seaman@infracaninophile.co.uk) Received: from [172.16.3.238] (gateway.ash.thebunker.net [213.129.64.4]) (authenticated bits=0) by smtp.infracaninophile.co.uk (8.13.8/8.13.8) with ESMTP id k8E8tKs7022038 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 14 Sep 2006 09:55:26 +0100 (BST) (envelope-from m.seaman@infracaninophile.co.uk) Authentication-Results: smtp.infracaninophile.co.uk from=m.seaman@infracaninophile.co.uk; sender-id=softfail; spf=softfail X-SenderID: Sendmail Sender-ID Filter v0.2.14 smtp.infracaninophile.co.uk k8E8tKs7022038 Message-ID: <450918ED.6030206@infracaninophile.co.uk> Date: Thu, 14 Sep 2006 09:55:09 +0100 From: Matthew Seaman Organization: Infracaninophile User-Agent: Thunderbird 1.5.0.5 (X11/20060817) MIME-Version: 1.0 To: RJ45 References: In-Reply-To: X-Enigmail-Version: 0.94.0.0 Content-Type: multipart/signed; micalg=pgp-ripemd160; protocol="application/pgp-signature"; boundary="------------enig9DC83E041CB514700A69BA14" X-Greylist: Sender succeeded SMTP AUTH authentication, not delayed by milter-greylist-2.0.2 (smtp.infracaninophile.co.uk [81.187.76.162]); Thu, 14 Sep 2006 09:55:46 +0100 (BST) X-Virus-Scanned: ClamAV 0.88.4/1879/Wed Sep 13 22:42:16 2006 on happy-idiot-talk.infracaninophile.co.uk X-Virus-Status: Clean X-Spam-Status: No, score=-1.5 required=5.0 tests=AWL,BAYES_00, DKIM_POLICY_TESTING,SPF_SOFTFAIL autolearn=no version=3.1.5 X-Spam-Checker-Version: SpamAssassin 3.1.5 (2006-08-29) on happy-idiot-talk.infracaninophile.co.uk Cc: freebsd-questions@freebsd.org Subject: Re: memory problem X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 14 Sep 2006 08:55:54 -0000 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig9DC83E041CB514700A69BA14 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: quoted-printable RJ45 wrote: > THe system has exactly 4GB of memory but the memory is not complitely > seen by the system. >=20 > At boot thime I Get this warning >=20 > 524288Kb of memory above 4GB ignored A normal 32bit OS can only address 4GB RAM -- but your system has various= L2 and other caches built into the CPUs, etc., which count towards the to= tal RAM count. So the excess is trimmed from the main memory. If you need to use more than 4GB RAM then either switch to a 64Bit OS, or= =20 investigate 'PAE'. You can run the 64bit version of FreeBSD on Intel Xeons (so long as they support EMT64) or the various AMD 64 bit processors. Xeons don't have as= complete 64-bitness as Opterons so performance may not be as good as runn= ing 32bit. Mind you that sort of thing depends heavily on the particular workload and you should benchmark against your expected workloads. PAE 'Page Alternate Extensions' is frankly a bit of a haque to allow acce= ss to more than 4GB RAM by giving each process it's own separate 4GB address sp= ace, rather than sharing the space between all processes. Any one process can= not grow beyond 4GB, but the total over all processes can be more than 4GB. = There is support in FreeBSD but with some severe limitations. Many drivers are= not compatible with a PAE system. > and then if I check >=20 > real memory =3D 3757965312 (3583 MB) > avail memory =3D 3678597120 (3508 MB) >=20 > I do not know why this happens. That number is the amount of memory less what is wired down for the kerne= l. If you're on a 'big' system -- with lots of RAM -- then the kernel itself= has to be larger because it needs to allocate memory to contain page mapp= ings etc. etc. Approximately 500MB consumed by the kernel is not unreasonable = for such a machine. Cheers, Matthew --=20 Dr Matthew J Seaman MA, D.Phil. Flat 3 7 Priory Courtyard PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate Kent, CT11 9PW, UK --------------enig9DC83E041CB514700A69BA14 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (FreeBSD) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFFCRj18Mjk52CukIwRA9HIAJ9M6zEqeq+LVOYrfqrYlxqlORKSIwCeLCer 19apcqFREyruyTCqehcHXXc= =tLCp -----END PGP SIGNATURE----- --------------enig9DC83E041CB514700A69BA14--