On Sun, Apr 22, 2012 at 11:16 AM, Ahmet Inan <ai...@mathematik.uni-freiburg.de> wrote: > On Sun, Apr 22, 2012 at 9:59 AM, Sergei Trofimovich <sly...@gmail.com> wrote: >> On Sat, 21 Apr 2012 22:54:41 +0200 >> Ahmet Inan <ai...@mathematik.uni-freiburg.de> wrote: >> >>> On Fri, Apr 13, 2012 at 3:47 PM, Josef Bacik <jo...@redhat.com> wrote: >>> > On Fri, Apr 13, 2012 at 02:26:19PM +0200, Ahmet Inan wrote: >>> >> On Fri, Apr 13, 2012 at 1:22 PM, Ahmet Inan >>> >> <ai...@mathematik.uni-freiburg.de> wrote: >>> >> > On Fri, Apr 13, 2012 at 8:49 AM, cwillu <cwi...@cwillu.com> wrote: >>> >> >>> dmesg and fstab attached as requested. >>> >> >> >>> >> >> Need dmesg after you've hit alt-sysrq-w a couple times during the >>> >> >> slow period. >>> >> > >>> >> > here. >>> >> > >>> >> > i guess i should also increase dmesg history size next time. >>> >> > other than the slow boot, everything seems normal after 10-20minutes. >>> >> > >>> >> > fyi: the space_cache option is not really helping with those >>> >> > twenty computers. the one thing i observed is, that sometimes >>> >> > they reboot fast and only to reboot slow again after that. >>> >> >>> >> sorry for spaming the list with my dmesg files, >>> >> please tell me, how i could do better. >>> >> >>> >> here a more complete dmesg. >>> > >>> > Hrm so you are getting blocked task warnings just trying to mount the >>> > filesystem, so either your disk is really really really slow or there's >>> > something bigger going on. Let me think about this some and I'll get >>> > back to >>> > you. >>> >>> Josef, i finally found out something: >>> >>> btrfs in kernel => fast boot >>> btrfs as module => very slow boot >>> >>> and here see the results: >>> http://aam.mathematik.uni-freiburg.de/IAM/homepages/ainan/bootchart_btrfs_in_kernel.png >>> >>> this is much, much better! >>> >>> I dont understand why btrfs as a module performs that bad on rotating disk. >>> On SSD i had no issues and also i never used space_cache before. >> >> There is a suspiction that putting space_cache (or anything else) to fstab >> for rootfs >> does not get applied due to a bug: >> >> http://www.mail-archive.com/linux-btrfs@vger.kernel.org/msg16039.html > > Thats right. > > space_cache only got enabled for real, after ive set the option in the > boot argument once. > Even if it looks like it gets enabled in dmesg via /etc/fstab, > the next boot without space_cache doesnt show space_cache enabled. > > But this is another problem i will look into later.
I just pulled for-linus and thank you for that patch Sergei. Now i can enable space_cache on all systems without playing with bootarguments or fstab: # mount -o remount,space_cache / it speeds up boot times after a couple reboots. perfect! > At the moment the biggest problem is having btrfs as a module. To be sure i just rebooted that troublesome computer again with btrfs as module and with space_cache enabled: http://aam.mathematik.uni-freiburg.de/IAM/homepages/ainan/bootchart_btrfs_as_module.png So it looks like btrfs as module only amplified that space_cache problem .. And now that space_cache is enabled and working even btrfs as module works ok. Conclusion: btrfs in kernel + space_cache solves all my slow boot problems. Ahmet -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
