[Bug 574910] Re: High load averages on Lucid while idling

[Chris]

I too have problems with high load averages on "unloaded" systems.   For
a while I thought this was due to my running Ubuntu Lucid under
Virtualbox.   One of my  hosts (violet) is a Virtuabox VM
w/2.6.32-24-generic #38-Ubuntu SMP running.  It has Firefox 3.6, Pigeon
and a terminal window open .

top - 22:13:25 up 2 days,  8:29,  2 users,  load average: 1.87, 1.24, 1.07
Tasks: 142 total,   1 running, 141 sleeping,   0 stopped,   0 zombie
Cpu(s):  1.0%us,  0.0%sy,  0.0%ni, 99.0%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st

It has been like this, unused for over an hour.  A 'sar -P' shows that
the lowest load average was 0.45 and the highest was 2.0 during the last
22 hours.  the bulk of the time it was at a load avg of > 1.04

Running iotop on violet I can see that the disk reads/writes are very
small (iotop updates every other second and only every third update
shows activity at the sub 100kb level).  There is little to no network
activity, and there is still room left to make disk cache of free ram.
IOTOP would be of more use if the maintainers of the Ubuntu Kernel would
re-enable CONFIG_TASK_DELAY_ACCT, but apparently that causes more lost
cycles than enabling SMP in non-smp environments does.

I thought for a while it may have been some sort of AMD-64 bug, but I also get this issue in  on my core2-64 duo system at work. (If I retrograde the 10.04 release to 2.6.31-XX-generic (where XX =< 19) kernel the problem is reduced or becomes less pronounced. )   My work host is running Ubuntu 10.04 running the 2.6.32-2X-generic kernel and it  went ballistic when I plugged in a new 4GB thumb drive and did a  dd if=/dev/zero of=/path/to/thumb/drive/foo bs=1020 count=1M .  to test the speed of the device.  The load average went above 10 though it was only a little sluggish when switching to the other VMs.
My home host on 9.10 w/ Linux  2.6.31-20-generic #58-Ubuntu SMP, and my primary Linux host is Ubuntu 9.10 w/ Linux  2.6.31-17-generic and both run with little or no issues related to load average.    If I use the default kernel with the Lucid release in a VM  on either  AMD or Core2 the guest is nearly unusable due to the load averages going above 10 and causing issues (core dumps et all).  I don't know what the cause of the high load avg is since the swap and disk IO were low to non-existent.  There were no conflicting VMs running, etc.     I will try this out on my work laptop (core2-32bit) 

Any idea when the issue might be resolved?   Is there a Linux
"distribution" where this is not an issue? Is this a kernel issue or
something else in the  release?     I see that a few have complained
about this issue.  I see it has been an issue for some time.   Is this
currently a very low priority?  Are there plans to extend support for
8.04 for an additional 4 months since this problem has not been resolved
yet?   I can imagine that this would be of great interest to those
planning moves from 8.04 LTS.

-- 
High load averages on Lucid while idling
https://bugs.launchpad.net/bugs/574910
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