Bug#594923: Noflushd causes flush- processes to eat all CPU
Le 03/03/2012 14:55, Jonathan Nieder a écrit :
> Thanks. Does the attached patch help?
Yes, mostly.
It took me a while (the test machine was randomly freezing because of
unrelated ACPI issue) but the patch does appears to fix the noflushd
problem.
With original 2.6.32-5-686 (fresh squeeze install on a x86 machine)
after 15 minutes of uptime and noflushd running:
354 root 20 0 0 0 0 R 50.8 0.0 0:24.36 flush-8:0
13101 root 20 0 0 0 0 R 46.9 0.0 0:14.12 flush-8:32
(/etc/init.d/noflushd stop "clears" the issue)
With the patched kernel (linux-2.6_2.6.32.orig.tar.gz +
writeback-fixups-for-dirty_writeback_centisecs.patch --
linux-2.6_2.6.32-41.diff not applied), I do not have anymore the flush
problem.
However, the ksoftirqd process shows up time to time and eats some CPU:
4 root 20 0 0 0 0 R 28.2 0.0 0:06.55 ksoftirqd/0
This is not an issue as the load average stays very low (0,10) ; but the
problem disappears totally when using 3.2.9.
[ Note: if a disk is going idle because of a previous "/sbin/hdparm
-SXXX /dev/sdXXX", the 100% CPU issue comes back (but can be solved by
awakening the disk), which is not the case in 3.2.9, strangely. ]
Reply to: