On Thu, Apr 12, 2012 at 4:23 PM, Josef Bacik <josef@xxxxxxxxxx> wrote: > On Thu, Apr 12, 2012 at 09:37:48AM -0400, Josef Bacik wrote: >> On Thu, Apr 12, 2012 at 11:22:51AM +0200, Ahmet Inan wrote: >> > On Wed, Apr 11, 2012 at 7:04 PM, Josef Bacik <josef@xxxxxxxxxx> wrote: >> > > On Wed, Apr 11, 2012 at 05:26:29PM +0200, Ahmet Inan wrote: >> > >> On Tue, Apr 10, 2012 at 5:16 PM, Josef Bacik <josef@xxxxxxxxxx> wrote: >> > >> > On Mon, Apr 09, 2012 at 05:20:46PM -0400, Calvin Walton wrote: >> > >> >> On Mon, 2012-04-09 at 16:54 -0400, Josef Bacik wrote: >> > >> >> > On Mon, Apr 09, 2012 at 01:10:04PM -0400, Calvin Walton wrote: >> > >> >> > > On Mon, 2012-04-09 at 11:53 -0400, Calvin Walton wrote: >> > >> >> > > > Hi, >> > >> >> > > > >> > >> >> > > > I have a system that's using a dracut-generated initramfs to mount a >> > >> >> > > > btrfs root. After upgrading to kernel 3.4.0-rc2 to test it out, I've >> > >> >> > > > noticed that the process of mounting the root filesystem takes much >> > >> >> > > > longer with 3.4.0-rc2 than it did with 3.3.1 - nearly 30 seconds slower! >> > >> >> >> > >> >> > > And the bisect results are in: >> > >> >> > > 285ff5af6ce358e73f53b55c9efadd4335f4c2ff is the first bad commit >> > >> >> > > commit 285ff5af6ce358e73f53b55c9efadd4335f4c2ff >> > >> >> > > Author: Josef Bacik <josef@xxxxxxxxxx> >> > >> >> > > Date: Fri Jan 13 15:27:45 2012 -0500 >> > >> >> > > >> > >> >> > > Btrfs: remove the ideal caching code> >> > >> >> > >> > >> >> > Ok can you give this a whirl? You are going to have to boot/reboot a few times >> > >> >> > to let the cache get re-generated again to make sure it's taken effect, but >> > >> >> > hopefully this will help out. Thanks, >> > >> >> >> > >> >> Unfortunately, it doesn't seem to help. Even after 3 or 4 reboots with >> > >> >> this patch applied I'm still seeing the same delay. >> > >> >> >> > >> > >> > >> > Ok drop that previous patch and give this one a whirl, it helped on my laptop. >> > >> > This is only half of the problem AFAICS, but it's the easier half to fix, in >> > >> > the meantime I need to lock down why we're not writing out cache for a bunch of >> > >> > block groups, but thats trickier since the messages I need are spit out while >> > >> > I'm shutting down, so I need to get creative. Let me know if/how much this >> > >> > helps. Thanks, >> > >> >> > >> i have tried your patch and my system still needs several minutes to boot >> > >> until it can be used. >> > >> Also tried to reboot several times - it doesn't look like its getting better. >> > >> The last thing the system does when its shutting down is a read-only >> > >> remount of "/" so no umount. >> > >> Booting was much faster before i pulled for-linus a few weeks ago but >> > >> i couldn't find the time to bisect it yet .. >> > >> >> > >> please also look at the attached dmesg.txt. >> > >> this is an core i3 system with 2x2TB BTRFS RAID1 and lots of >> > >> home directories and snapshots. >> > >> >> > >> I'm going to test this patch on twenty more computers but with >> > >> smaller HDDs and less files and see if it helps to speed up their >> > >> boot times. >> > >> >> > > >> > > Ok looks like you are running into a different problem. Could you maybe run >> > > bootchart and upload the resulting png somewhere so I can look and see what all >> > > is running while you boot? Thanks, >> > >> > http://aam.mathematik.uni-freiburg.de/IAM/homepages/ainan/bootchart.png >> > >> > i have tried your patch now on the twenty more computers i mentioned and >> > still it takes a minute to remount rw "/" on those, even after several reboots. >> > >> >> Oops responding to the whole list this time.. >> >> Um ouch your system appears to not be doing anything for like 300 seconds but >> sitting there. Can you hook up a console and capture sysrq+w while thats going >> on? Also you are mounting with -o space_cache right? Can I see your dmesg to >> make sure it's doing what it's supposed to? Thanks, >> > > Ok you don't actually have space_cache enabled it looks like, make sure to add > space_cache to your fstab so it gets enabled, and then reboot a few times to > make sure everything gets cached right and then it should help. Thanks, now i did enable space_cache in fstab and rebooted 4 times, still no improvement: http://aam.mathematik.uni-freiburg.de/IAM/homepages/ainan/bootchart_space_cache.png is it vital to put this space_cache option to the boot argument as well? mounting "/" readonly in initramfs and booting to it (until remount "/" rw) is quite fast. dmesg and fstab attached as requested. Ahmet
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