From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932286AbWDKHHy (ORCPT ); Tue, 11 Apr 2006 03:07:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932299AbWDKHHx (ORCPT ); Tue, 11 Apr 2006 03:07:53 -0400 Received: from ecfrec.frec.bull.fr ([129.183.4.8]:64391 "EHLO ecfrec.frec.bull.fr") by vger.kernel.org with ESMTP id S932286AbWDKHHw (ORCPT ); Tue, 11 Apr 2006 03:07:52 -0400 Subject: Re: [Ext2-devel] Re: [RFC][PATCH 0/2]Extend ext3 filesystem limit from 8TB to 16TB From: Laurent Vivier To: Mingming Cao Cc: kiran@scalex86.org, Andrew Morton , Takashi Sato , linux-kernel@vger.kernel.org, ext2-devel , linux-fsdevel@vger.kernel.org In-Reply-To: <1144696012.3964.76.camel@dyn9047017067.beaverton.ibm.com> References: <20060325223358sho@rifu.tnes.nec.co.jp> <1143485147.3970.23.camel@dyn9047017067.beaverton.ibm.com> <20060327131049.2c6a5413.akpm@osdl.org> <20060327225847.GC3756@localhost.localdomain> <1143530126.11560.6.camel@openx2.frec.bull.fr> <1143568905.3935.13.camel@dyn9047017067.beaverton.ibm.com> <1143623605.5046.11.camel@openx2.frec.bull.fr> <1143682730.4045.145.camel@dyn9047017067.beaverton.ibm.com> <20060329175446.67149f32.akpm@osdl.org> <1144660270.5816.3.camel@openx2.frec.bull.fr> <1144688279.3964.7.camel@dyn9047017067.beaverton.ibm.com> <1144696012.3964.76.camel@dyn9047017067.beaverton.ibm.com> Message-Id: <1144739259.9786.5.camel@openx2.frec.bull.fr> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.5 (1.4.5-14) Date: Tue, 11 Apr 2006 09:07:39 +0200 X-MIMETrack: Itemize by SMTP Server on ECN002/FR/BULL(Release 5.0.12 |February 13, 2003) at 11/04/2006 09:10:09, Serialize by Router on ECN002/FR/BULL(Release 5.0.12 |February 13, 2003) at 11/04/2006 09:10:12, Serialize complete at 11/04/2006 09:10:12 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-SVlWzbZRpk5G4VFumb2x" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --=-SVlWzbZRpk5G4VFumb2x Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Le lun 10/04/2006 =C3=A0 21:06, Mingming Cao a =C3=A9crit : > On Mon, 2006-04-10 at 09:57 -0700, Mingming Cao wrote: > > On Mon, 2006-04-10 at 11:11 +0200, Laurent Vivier wrote: [...] > Hi Laurent, >=20 > Just looked at your patch, shouldn't we use atomic_long_add() instead of > atomic_long_set() to replace percpu_counter_mod()? Yes, thank you. > > I tried the other way -- I am trying to keep the percpu counter in use > > in ext2/3 as much as possible. I proposed a fix for percpu counter to > > deal with the possible "overflow" (i.e, a counter really has a value of > > 0xfff_feee and after updating one local counter it truens 0x00000123). > > Will send the proposed patch out for review and comments soon. > >=20 >=20 > Anyway, I am not against the atomic way. Just thought there must be > reasons where we use percpu counters -- the cache pollution on smp > machine is certainly a concern if we use atomic instead, so I tried to > fix percpu counter first. >=20 > I think my fix for percpu counter should work, and the changes doesn't > affect other users of current percpu counters(vfs and network). Kiran, > Andrew, please review it (posted in another seperate thread). If not, > then I guess we have to use atomic counter -- this is performance vs > capacity kind of trade off. I made some tests with iozone on 2 CPU hyperthreaded computer (=3D 4 CPUs, Bull Express 5800 120 Lh), and it seems atomic_t is faster than "percpu_counter". I'll try to make some tests on IBM x440 (8 CPUs, 16 if hyperthreaded) with iozone and sysbench. Moreover, I think percpu_counter uses a lot of memory... > But both methods don't support 64 bit ext3 block number on 32 bit > machine...I am not happy with this but can't think of a way to fix this > without taking a global lock:( Anyway, wa can't have a 64bit addressing space on a 32bit machine, so I think, for the moment, it's not a problem. Regards, Laurent --=20 Laurent Vivier Bull, Architect of an Open World (TM) http://www.bullopensource.org/ext4 --=-SVlWzbZRpk5G4VFumb2x Content-Type: application/pgp-signature; name=signature.asc Content-Description: Ceci est une partie de message =?ISO-8859-1?Q?num=E9riquement?= =?ISO-8859-1?Q?_sign=E9e=2E?= -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.7 (GNU/Linux) iD8DBQBEO1W79Kffa9pFVzwRAlh/AJ0Qw4D6O3E86K1PmP6Do6uBJAea3QCgwoPU 5eBAYjl6sRJvnMUSajbQBNw= =aqzM -----END PGP SIGNATURE----- --=-SVlWzbZRpk5G4VFumb2x--