Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754157AbXKARJW (ORCPT ); Thu, 1 Nov 2007 13:09:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753281AbXKARJO (ORCPT ); Thu, 1 Nov 2007 13:09:14 -0400 Received: from viefep18-int.chello.at ([213.46.255.22]:4874 "EHLO viefep14-int.chello.at" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753340AbXKARJN (ORCPT ); Thu, 1 Nov 2007 13:09:13 -0400 Subject: Re: per-bdi-throttling: synchronous writepage doesn't work correctly From: Peter Zijlstra To: Miklos Szeredi Cc: jdike@addtoit.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org In-Reply-To: References: <1193935886.27652.313.camel@twins> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-dSa74V+mZJnKJ/sKvoKp" Date: Thu, 01 Nov 2007 18:09:09 +0100 Message-Id: <1193936949.27652.321.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.10.1 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1698 Lines: 52 --=-dSa74V+mZJnKJ/sKvoKp Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Thu, 2007-11-01 at 18:00 +0100, Miklos Szeredi wrote: > > > Hi, > > >=20 > > > It looks like bdi_thresh will always be zero if filesystem does > > > synchronous writepage, resulting in very poor write performance. > > >=20 > > > Hostfs (UML) is one such example, but there might be others. > > >=20 > > > The only solution I can think of is to add a set_page_writeback(); > > > end_page_writeback() pair (or some reduced variant, that only does > > > the proportions magic). But that means auditing quite a few > > > filesystems... > >=20 > > Ouch... > >=20 > > I take it there is no other function that is shared between all these > > writeout paths which we could stick a bdi_writeout_inc(bdi) in? >=20 > No, and you can't detect it from the callers either I think. The page not having PG_writeback set on return is a hint, but not fool proof, it could be the device is just blazing fast. I guess there is nothing to it but for me to grep writepage and manually look at all hits... --=-dSa74V+mZJnKJ/sKvoKp Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQBHKgg1XA2jU0ANEf4RAn80AJ47Qu81P9UszpqrtAsdBGtbBKwqUgCbBQJg 6hM3NjbF6zxEbRDKfNQgLyc= =AUR4 -----END PGP SIGNATURE----- --=-dSa74V+mZJnKJ/sKvoKp-- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/