From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 26 Jul 2007 03:09:02 -0700 From: Andrew Morton Subject: Re: RFT: updatedb "morning after" problem [was: Re: -mm merge plans for 2.6.23] Message-Id: <20070726030902.02f5eab0.akpm@linux-foundation.org> In-Reply-To: <20070726094024.GA15583@elte.hu> References: <9a8748490707231608h453eefffx68b9c391897aba70@mail.gmail.com> <46A57068.3070701@yahoo.com.au> <2c0942db0707232153j3670ef31kae3907dff1a24cb7@mail.gmail.com> <46A58B49.3050508@yahoo.com.au> <2c0942db0707240915h56e007e3l9110e24a065f2e73@mail.gmail.com> <46A6CC56.6040307@yahoo.com.au> <46A85D95.509@kingswood-consulting.co.uk> <20070726092025.GA9157@elte.hu> <20070726023401.f6a2fbdf.akpm@linux-foundation.org> <20070726094024.GA15583@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Ingo Molnar Cc: Frank Kingswood , Andi Kleen , Nick Piggin , Ray Lee , Jesper Juhl , ck list , Paul Jackson , linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On Thu, 26 Jul 2007 11:40:24 +0200 Ingo Molnar wrote: > > * Andrew Morton wrote: > > > On Thu, 26 Jul 2007 11:20:25 +0200 Ingo Molnar wrote: > > > > > Once we give the kernel the knowledge that the dentry wont be used again > > > by this app, the kernel can do a lot more intelligent decision and not > > > baloon the dentry cache. > > > > > > ( we _do_ want to baloon the dentry cache otherwise - for things like > > > "find" - having a fast VFS is important. But known-use-once things > > > like the daily updatedb job can clearly be annotated properly. ) > > > > Mutter. /proc/sys/vm/vfs_cache_pressure has been there for what, > > three years? Are any distros raising it during the updatedb run yet? > > but ... that's system-wide, and the 'dont baloon the dcache' is only a > property of updatedb. Sure, but it's practical, isn't it? Who runs (and cares about) vfs-intensive workloads during their wee-small-hours updatedb run? (OK, I do, but I kill the damn thing if it goes off) > Still, it's useful to debug this thing. > > below is an updatedb hack that sets vfs_cache_pressure down to 0 during > an updatedb run. Could someone who is affected by the 'morning after' > problem give it a try? If this works then we can think about any other > measures ... > > Ingo > > --- /etc/cron.daily/mlocate.cron.orig > +++ /etc/cron.daily/mlocate.cron > @@ -1,4 +1,7 @@ > #!/bin/sh > nodevs=$(< /proc/filesystems awk '$1 == "nodev" { print $2 }') > renice +19 -p $$ >/dev/null 2>&1 > +PREV=`cat /proc/sys/vm/vfs_cache_pressure 2>/dev/null` > +echo 0 > /proc/sys/vm/vfs_cache_pressure 2>/dev/null > /usr/bin/updatedb -f "$nodevs" > +[ "$PREV" != "" ] && echo $PREV > /proc/sys/vm/vfs_cache_pressure 2>/dev/null Setting it to zero will maximise the preservation of the vfs caches. You wanted 10000 there. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org