From: "Mike Snitzer" Subject: Re: regression: 100% io-wait with 2.6.24-rcX Date: Wed, 16 Jan 2008 11:27:54 -0500 Message-ID: <170fa0d20801160827p73ae28d0u702120a4f9f48936@mail.gmail.com> References: <230154.6549.qm@web32604.mail.mud.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "Fengguang Wu" , "Peter Zijlstra" , jplatte@naasa.net, "Ingo Molnar" , linux-kernel@vger.kernel.org, "linux-ext4@vger.kernel.org" , "Linus Torvalds" To: "Martin Knoblauch" Return-path: Received: from nz-out-0506.google.com ([64.233.162.236]:19794 "EHLO nz-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752575AbYAPQ14 (ORCPT ); Wed, 16 Jan 2008 11:27:56 -0500 Received: by nz-out-0506.google.com with SMTP id s18so259126nze.1 for ; Wed, 16 Jan 2008 08:27:54 -0800 (PST) In-Reply-To: <230154.6549.qm@web32604.mail.mud.yahoo.com> Content-Disposition: inline Sender: linux-ext4-owner@vger.kernel.org List-ID: On Jan 16, 2008 9:15 AM, Martin Knoblauch wrote: > ----- Original Message ---- > > From: Fengguang Wu > > To: Martin Knoblauch > > Cc: Mike Snitzer ; Peter Zijlstra ; jplatte@naasa.net; Ingo Molnar ; linux-kernel@vger.kernel.org; "linux-ext4@vger.kernel.org" ; Linus Torvalds > > Sent: Wednesday, January 16, 2008 1:00:04 PM > > Subject: Re: regression: 100% io-wait with 2.6.24-rcX > > > > > On Wed, Jan 16, 2008 at 01:26:41AM -0800, Martin Knoblauch wrote: > > > > For those interested in using your writeback improvements in > > > > production sooner rather than later (primarily with ext3); what > > > > recommendations do you have? Just heavily test our own 2.6.24 > > + > > > your > > > > evolving "close, but not ready for merge" -mm writeback patchset? > > > > > > > Hi Fengguang, Mike, > > > > > > I can add myself to Mikes question. It would be good to know > > a > > > "roadmap" for the writeback changes. Testing 2.6.24-rcX so far has > > been > > > showing quite nice improvement of the overall writeback situation and > > it > > > would be sad to see this [partially] gone in 2.6.24-final. > > Linus > > > apparently already has reverted "...2250b". I will definitely repeat my > > tests > > > with -rc8. and report. > > > > Thank you, Martin. Can you help test this patch on 2.6.24-rc7? > > Maybe we can push it to 2.6.24 after your testing. > > > > Will do tomorrow or friday. Actually a patch against -rc8 would be nicer for me, as I have not looked at -rc7 due to holidays and some of the reported problems with it. Fengguang's latest writeback patch applies cleanly, builds, boots on 2.6.24-rc8. I'll be able to share ext3 performance results (relative to 2.6.24-rc7) shortly. Mike > > > > Fengguang > > --- > > fs/fs-writeback.c | 17 +++++++++++++++-- > > include/linux/writeback.h | 1 + > > mm/page-writeback.c | 9 ++++++--- > > 3 files changed, 22 insertions(+), 5 deletions(-) > > > > --- linux.orig/fs/fs-writeback.c > > +++ linux/fs/fs-writeback.c > > @@ -284,7 +284,16 @@ __sync_single_inode(struct inode *inode, > > * soon as the queue becomes uncongested. > > */ > > inode->i_state |= I_DIRTY_PAGES; > > - requeue_io(inode); > > + if (wbc->nr_to_write <= 0) > > + /* > > + * slice used up: queue for next turn > > + */ > > + requeue_io(inode); > > + else > > + /* > > + * somehow blocked: retry later > > + */ > > + redirty_tail(inode); > > } else { > > /* > > * Otherwise fully redirty the inode so that > > @@ -479,8 +488,12 @@ sync_sb_inodes(struct super_block *sb, s > > iput(inode); > > cond_resched(); > > spin_lock(&inode_lock); > > - if (wbc->nr_to_write <= 0) > > + if (wbc->nr_to_write <= 0) { > > + wbc->more_io = 1; > > break; > > + } > > + if (!list_empty(&sb->s_more_io)) > > + wbc->more_io = 1; > > } > > return; /* Leave any unwritten inodes on s_io */ > > } > > --- linux.orig/include/linux/writeback.h > > +++ linux/include/linux/writeback.h > > @@ -62,6 +62,7 @@ struct writeback_control { > > unsigned for_reclaim:1; /* Invoked from the page > > allocator > > > */ > > unsigned for_writepages:1; /* This is a writepages() call */ > > unsigned range_cyclic:1; /* range_start is cyclic */ > > + unsigned more_io:1; /* more io to be dispatched */ > > }; > > > > /* > > --- linux.orig/mm/page-writeback.c > > +++ linux/mm/page-writeback.c > > @@ -558,6 +558,7 @@ static void background_writeout(unsigned > > global_page_state(NR_UNSTABLE_NFS) < background_thresh > > && min_pages <= 0) > > break; > > + wbc.more_io = 0; > > wbc.encountered_congestion = 0; > > wbc.nr_to_write = MAX_WRITEBACK_PAGES; > > wbc.pages_skipped = 0; > > @@ -565,8 +566,9 @@ static void background_writeout(unsigned > > min_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write; > > if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) { > > /* Wrote less than expected */ > > - congestion_wait(WRITE, HZ/10); > > - if (!wbc.encountered_congestion) > > + if (wbc.encountered_congestion || wbc.more_io) > > + congestion_wait(WRITE, HZ/10); > > + else > > break; > > } > > } > > @@ -631,11 +633,12 @@ static void wb_kupdate(unsigned long arg > > global_page_state(NR_UNSTABLE_NFS) + > > (inodes_stat.nr_inodes - inodes_stat.nr_unused); > > while (nr_to_write > 0) { > > + wbc.more_io = 0; > > wbc.encountered_congestion = 0; > > wbc.nr_to_write = MAX_WRITEBACK_PAGES; > > writeback_inodes(&wbc); > > if (wbc.nr_to_write > 0) { > > - if (wbc.encountered_congestion) > > + if (wbc.encountered_congestion || wbc.more_io) > > congestion_wait(WRITE, HZ/10); > > else > > break; /* All the old data is written */ > > > > > > > > >