From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ahmet Inan Subject: Re: Boot speed/mount time regression with 3.4.0-rc2 Date: Sat, 21 Apr 2012 22:54:41 +0200 Message-ID: References: <20120410151645.GC2296@localhost.localdomain> <20120411170422.GA2506@localhost.localdomain> <20120412133747.GE1924@localhost.localdomain> <20120412142349.GI1924@localhost.localdomain> <20120413134716.GB1923@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: cwillu , Calvin Walton , linux-btrfs@vger.kernel.org, Chris Mason To: Josef Bacik Return-path: In-Reply-To: <20120413134716.GB1923@localhost.localdomain> List-ID: On Fri, Apr 13, 2012 at 3:47 PM, Josef Bacik 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 >> wrote: >> > On Fri, Apr 13, 2012 at 8:49 AM, cwillu 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 10-20minut= es. >> > >> > 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. =C2=A0Let me think about this some and I'l= l get back to > you. Josef, i finally found out something: btrfs in kernel =3D> fast boot btrfs as module =3D> very slow boot and here see the results: http://aam.mathematik.uni-freiburg.de/IAM/homepages/ainan/bootchart_btr= fs_in_kernel.png this is much, much better! I dont understand why btrfs as a module performs that bad on rotating d= isk. On SSD i had no issues and also i never used space_cache before. Im going to deploy the new kernel on our systems next week with btrfs in-kernel and come back with the results. Ahmet -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" = in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html