From: Mike Galbraith Subject: Re: [PATCH] Add ext3 data=guarded mode Date: Mon, 20 Apr 2009 14:15:14 +0200 Message-ID: <1240229714.6469.33.camel@marge.simson.net> References: <1239816159-6868-1-git-send-email-chris.mason@oracle.com> <1239910921.21233.98.camel@think.oraclecorp.com> <20090417180906.GA8363@amit-x200.pnq.redhat.com> <20090417201342.GF26479@mit.edu> <20090418060312.GA10943@amit-x200.pnq.redhat.com> <1240039701.6298.12.camel@marge.simson.net> <20090419062448.GA13272@amit-x200.pnq.redhat.com> <1240218437.7005.27.camel@marge.simson.net> <20090420092604.GB14699@duck.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Amit Shah , Theodore Tso , Chris Mason , Linus Torvalds , Linux Kernel Developers List , Ext4 Developers List To: Jan Kara Return-path: Received: from mail.gmx.net ([213.165.64.20]:50203 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754918AbZDTMPV (ORCPT ); Mon, 20 Apr 2009 08:15:21 -0400 In-Reply-To: <20090420092604.GB14699@duck.suse.cz> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Mon, 2009-04-20 at 11:26 +0200, Jan Kara wrote: > On Mon 20-04-09 11:07:17, Mike Galbraith wrote: > > All journal modes seem subject to bad throughput under heavy pressu= re, > > though data=3Dordered seems much less likely to suffer for some rea= son. > > Major difference _seems_ to be that write()+largefile induces very = much > > swap activity. > My rough guess is that this depends on the VM writeout behavior. In > ordered mode, we forcibly writeout all the dirty data on a transactio= n > commit which happens every 5 seconds so they don't accumulate that mu= ch. Aha. > In other journaling modes we don't do that and decisions about writeo= ut > (probably how much pdflush manages to write in background vs. how muc= h > VM throttles the process to do the writeback itself) cause variances = in > the run time. But this is just a guess. You could gather blktraces of > slow and fast runs and then look if the amount of IO done by differen= t > processes significantly differs. If Chris has merged by improvements = to > Seekwatcher, then you could nicely visualize this (hmm, that doesn't = seem > to be the case so I'm attaching the diff and a helper script - see co= mments > in the beginning of the script and command helps for usage). Not necessary methinks. Actually _reading_ the proggy instead of just glancing at it... @@ -178,7 +178,7 @@ int do_write_chunks(char *target, int *f unsigned long long remain =3D len; char *zeros; - zeros =3D calloc(1, len); + zeros =3D calloc(1, data); =EF=BB=BF I assume that was a booboo.=20 -Mike -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html