Intermittent system hangs on 7.2-RELEASE-p1

[Nate Eldredge]

On Wed, 26 Aug 2009, Linda Messerschmidt wrote:

> I'm trying to troubleshoot an intermittent Apache performance problem,
> and I've narrowed it down using to what appears to be a brief
> whole-system hang that last from 0.5 - 3 seconds.  They occur every
> few minutes.

One thought would be to use "ps" to try to determine which process, if 
any, is charged with CPU time during the hang.

If you could afford a little downtime, it would be worth seeing if the 
hang occurs in single-user mode (perhaps with a simple program that loops 
calling gettimeofday() and warns when the time between successive 
iterations is large).

I once had a problem like this that I eventually traced to a power 
management problem.  (Specifically, the machine had a modem, and would 
hang for a few seconds whenever the line would ring.  It was apparently 
related to the Wake-On-Ring feature.)  If I remember correctly, disabling 
ACPI made it go away.  So that might be something to try, if rebooting is 
an option.

What are the similarities and differences in hardware and software among 
the affected machines (you mentioned there were several)?

-- 

Nate Eldredge
neldredge at math.ucsd.edu