Re: Linux 2.6.35.6

From: tmhikaru
Date: Mon Sep 27 2010 - 12:32:16 EST


I'm not exactly sure what's going on here and I'd like some help
figuring out what is. For some inexplicable reason, ever since I started
using the 2.6.35.x series with the 2.6.35.3 release, my loadaverages tend to
bounce anywhere from as low to .2 to 1.5 - constantly, while the machine
seems idle. Consistently, there are no programs in D state in ps aux output,
no cpu hogging programs running in top, nothing I can see that should
explain the bizzarely high load average. *Something* is wrong beyond the
mere loadaverage numbers going crazy however, since timed runs of kernel
compiles done with my distro's kernel and 2.6.35.5 show that while there is
no *apparent* use of cpu or disk showing in vmstat while the machine is
idle, the compiles on the newer kernel are taking approximately twice as
long as before. Now, while I could try to figure out what patch started the
problem, I think it would be a better idea for me to make sure I'm looking
for the actual problem in the right place. Therefore, I know that cpu use,
disk I/O, and the kernel can drive the load average up. Of these things, cpu
use and disk I/O are trackable in top/ps output (eg, a process in D state is
waiting on the disk to do something and can't sleep.) but I don't know if
there's any easy way to determine if the kernel itself is doing something
that's driving up the load average. It's perplexing me that I can see the
loadaverage constantly bouncing about but can't seem to find any reason why
it is doing so.

If you have any tips or recommendations on what I should use to
investigate this further, please let me know. Once I have ensured to my own
satisfaction that I'm not doing something bizzare that's screwing up my
machine, I'll make a detailed bug report and start on figuring out how to
use git bisect.

Tim McGrath

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