On Fri, Nov 02, 2007 at 08:42:05AM +0100, Torsten Kaiser wrote: > The Subject is still missleading, I'm using 2.6.23-mm1. > > On 11/2/07, Fengguang Wu <wfg@xxxxxxxxxxxxxxxx> wrote: > > On Thu, Nov 01, 2007 at 07:20:51PM +0100, Torsten Kaiser wrote: > > > On 11/1/07, Fengguang Wu <wfg@xxxxxxxxxxxxxxxx> wrote: > > > > On Wed, Oct 31, 2007 at 04:22:10PM +0100, Torsten Kaiser wrote: > > > > > Since 2.6.23-mm1 I also experience strange hangs during heavy writeouts. > > > > > Each time I noticed this I was using emerge (package util from the > > > > > gentoo distribution) to install/upgrade a package. The last step, > > > > > where this hang occurred, is moving the prepared files from a tmpfs > > > > > partion to the main xfs filesystem. > > > > > The hangs where not fatal, after a few second everything resumed > > > > > normal, so I was not able to capture a good image of what was > > > > > happening. > > > > > > > > Thank you for the detailed report. > > > > > > > > How severe was the hangs? Only writeouts stalled, all apps stalled, or > > > > cannot type and run new commands? > > > > > > Only writeout stalled. The emerge that was moving the files hung, but > > > everything else worked normaly. > > > I was able to run new commands, like coping the /proc/meminfo. > > > > But you mentioned in the next mail that `watch cat /proc/meminfo` > > could also be blocked for some time - I guess in the same time emerge > > was stalled? > > The behavior was different on these stalls. > On first report the writeout stopped completly, the emerge stopped, > but at that time a cat /proc/meminfo >~/stall/meminfo did succedd and > not stall. > About the watch cat /proc/meminfo, I will write in the answer to the > other mail... OK. > > > [snip] > > > > > After this SysRq+W writeback resumed again. Possible that writing > > > > > above into the syslog triggered that. > > > > > > > > Maybe. Are the log files on another disk/partition? > > > > > > No, everything was going to / > > > > > > What might be interesting is, that doing cat /proc/meminfo > > > >~/stall/meminfo did not resume the writeback. So there might some > > > threshold that only was broken with the additional write from > > > syslog-ng. Or syslog-ng does some flushing, I dont now. (I'm using the > > > > Have you tried explicit `sync`? ;-) > > No. I wanted to see what is stalled. So I startet by collecting info > from /proc and then the SysRq+W. And after hitting SysRQ the writeout > started to resume without any further action. > > But I think I have seen a `sync` stall also. During an other emerge I > noticed the system slowing down and wanted to use `sync` to speed up > the writeout. The result was, that the writeout did not speed up > imiedetly only after around a minitue. The `sync` only returned at > that time. > Can writers starve `sync`? I guess the new debug printks will provide more hints on it. > > > syslog-ng package from gentoo: > > > http://www.balabit.com/products/syslog_ng/ , version 2.0.5) > > > > > > > > The source tmpfs is mounted with any special parameters, but the > > > > > target xfs filesystem resides on a dm-crypt device that is on top a 3 > > > > > disk RAID5 md. > > > > > During the hang all CPUs where idle. > > > > > > > > No iowaits? ;-) > > > > > > No, I have a KSysGuard in my taskbar that showed no activity at all. > > > > > > OK, the subject does not match for my case, but there was also a tmpfs > > > involved. And I found no thread with stalls on xfs. :-) > > > > Do you mean it is actually related with tmpfs? > > I don't know. It's just that I have seen tmpfs also redirtieing inodes > in these logs and the stalling emerge is moving files from tmpfs to > xfs. > It could be, but I don't know enough about tmpfs internals to really be sure. > I just wanted to mention, that tmpfs is involved somehow. The requeue messages for tmpfs are not pleasant, but known to be fine ;-) Fengguang - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
