[TAG] using smp kernel, get 100% cpu usage one one cpu without any real load on the system

[Ben Okopnik]

On Tue, Oct 09, 2007 at 12:48:33AM -0400, jim ruxton wrote:
> Ben Okopnik wrote:
> > 
> > One of the things that might be worth trying is reducing everything to a
> > minimum and seeing if it still happens. That is, try booting into single
> > mode and shutting down any non-critical processes, then just letting the
> > system "cook" for a little while. If it happens again, you've most
> > likely narrowed it down to either a) the kernel or b) the hardware. For
> > troubleshooting the former, check out the kernel compilation options (I
> > seem to recall a developer/debugging option accessible via 'make
> > config'.) For the latter, try a hairdryer aimed at the offending CPU. :)
>
> I tried switching into Single User Mode once the 1 processor jumped to
> 100% but it didn't seem to change anything. 

You need to go single-user _before_ it happens. That way, you'll know if
it's some program that you're running when you're not in single-user,
which is the valuable piece of info here.

> I've tried unloading some
> modules but I keep getting Resource currently unavailable after running
> rmmod. 

Sounds like your process table got filled up - that's when I've seen
that kind of message.

> Do you know what this would mean in this context? This glitch is
> hard to track down because sometimes it doesn't happen for a day or so
> after I've rebooted.

Unfortunately, this kind of problem usually breaks down to one of two
possibilities:

1) You're just Joe Average-User, messing around at home and trying to
learn something. Because of this, you have the leisure to experiment as
I suggested, so you spend several days twiddling and fiddling, and you
discover a kernel bug that earns you world-wide recognition, undying
fame, and a bouquet of roses from Linus Torvalds (*NOW* you'll be able
to get all the girls!)

2) You work in the corporate environment, and your company hasn't quite
yet spent the money on the spares that you've been begging them to get
for years. You curse them, curse the damn computers, and start madly
swapping hardware and kernels until it sorta kinda works (i.e., no
crashes in a 24-hour period), and forget all about it until the next
problem comes along.

Or there's always whatever intermediate version of these that you come
up with for yourself. Take your pick. :)


-- 
* Ben Okopnik * Editor-in-Chief, Linux Gazette * http://LinuxGazette.NET *