From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 6/7] writeback: separate starting of sync vs opportunistic writeback Date: Tue, 15 Sep 2009 09:08:29 -0400 Message-ID: <20090915130829.GA7507@infradead.org> References: <1252920994-11141-7-git-send-email-jens.axboe@oracle.com> <20090914133307.GJ24075@duck.suse.cz> <20090914134207.GA14830@infradead.org> <20090914192803.GL14984@kernel.dk> <20090914194242.GM14984@kernel.dk> <20090915090847.GA12169@duck.suse.cz> <20090915091402.GG23126@kernel.dk> <20090915114426.GJ23126@kernel.dk> <20090915125855.GF12169@duck.suse.cz> <20090915130419.GL23126@kernel.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jan Kara , Christoph Hellwig , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, chris.mason@oracle.com, tytso@mit.edu, akpm@linux-foundation.org, trond.myklebust@fys.uio.no To: Jens Axboe Return-path: Received: from bombadil.infradead.org ([18.85.46.34]:49185 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750738AbZIONI3 (ORCPT ); Tue, 15 Sep 2009 09:08:29 -0400 Content-Disposition: inline In-Reply-To: <20090915130419.GL23126@kernel.dk> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Tue, Sep 15, 2009 at 03:04:19PM +0200, Jens Axboe wrote: > > > Let's have a look at the flags in wbc: > > nonblocking - Currently only set by direct callers of ->writepage() BUT > > originally wb_kupdate() and background_writeout() also > > set this flag. Since filesystems and write_cache_pages() > > use the flag we should set it for equivalent writeouts as > > well. This should be fixed... > > Since this is all handled by the dedicated thread now, dropping the > nonblocking bit was on purpose. What would the point be, except for > stopping pdflush being blocked on request allocation? Note that this flag just caused utter mess traditionally. btrfs decided to ignore it completely and ext4 partially. Removing this check in XFS increases large bufferd write loads massively. Just half-removing it is a bad idea, though - if you don't set it anymore please kill it entirely.