Public bug reported:
After upgrading to the 3.2.0-33 kernel, our load averages have been
very, very odd. Here is a sample sar -q line:
15:05:02 runq-sz plist-sz ldavg-1 ldavg-5 ldavg-15 blocked
15:05:21 2 322 44.02 12.51 14.08 1
A run queue size of 2, with a load average of 44? So I wrote a script to
track run queue and uninterruptable sleep, since both contribute to load
average. Script is attached. Sample output during a run:
Stat Time Run+Sleep Load Avg
2012-11-28 15:47:53 2 71.54
2012-11-28 15:47:54 1 71.54
2012-11-28 15:47:55 1 71.54
2012-11-28 15:47:56 1 71.54
2012-11-28 15:47:57 1 71.54
2012-11-28 15:47:58 1 65.81
This behavior is not observed with kernel 3.2.0-31.
Problem can be reproduced with a basic pgbench test to simulate busy
state, but only seems to occur during rapid process cycling. An easy
simulation:
for x in {1..100}; do
pgbench -T 5 -j 2 -c 2 pgbench
sleep 1
done
Test may need to run for several minutes to trigger load spike. It will
look similar to this:
Stat Time Run+Sleep Load Avg
2012-11-28 16:01:17 3 10.37
2012-11-28 16:01:18 3 9.54
2012-11-28 16:01:19 3 9.54
2012-11-28 16:01:20 2 9.54
2012-11-28 16:01:21 5 9.54
2012-11-28 16:01:22 3 9.54
2012-11-28 16:01:23 1 47.94
System info:
Description: Ubuntu 12.04.1 LTS
Release: 12.04
Linux 3.2.0-33-generic #52-Ubuntu SMP Thu Oct 18 16:29:15 UTC 2012 x86_64
linux-image-3.2.0-33-generic:
Installed: 3.2.0-33.52
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: kernel-bug
** Attachment added: "Check load vs. running + blocked sleep processes"
https://bugs.launchpad.net/bugs/1084264/+attachment/3446276/+files/stat.sh
--
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/1084264
Title:
Kernel 3.2.0-33 Introduces Ridiculous / Impossible Load Averages
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1084264/+subscriptions
--
ubuntu-bugs mailing list
ubuntu-bugs@lists.ubuntu.com
https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
