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