CPUs running at 100% (Hardy Heron, Dell XPS M1330)

Thu Apr 1 19:00:22 UTC 2010

Hi

I've one of the Dell XPS M1330 machines that come shipped with Hardy
LTS (Dual Core T7300 2GHz/800Mhz 4MB Cache, 2GB RAM). I've had it for
a year and use it for scientific computing.

As of about 2 weeks ago I notice that the my youtube and BBC iplayer
playback started becoming jerky after a few minutes into any video.
I've not made any software changes recently. I ran the usual DELL
hardware checks and reinstalled my flash plugins, without improvement.
My laptop began freezing, including with standard applications like
openoffice or when running a CPU intensive job during analysis (I code
in R). So the problem appears to be my CPUs and I've confirmed, using
the system monitor, that they rapidly hit 100% before my laptop freezes.

I see there are some CPU tests out there, but have never
tinkered/tested with any CPUs before. I prize this machine (a lot) and
have heard horror stories around naive CPU testing. This has become a
real problem for me - I use this machine 10+ hours a day - so any
advice on what I should do next (explained to me like I'm an idiot)
and what the problem is likely to be would be very, very, very welcome!

Thanks a stack,
Quin

= = = = = =

Open a terminal and then type top. You will see a very busy
display and at the top it will show you the cpu amount used. If your
reaching near 100% use there must be something wrong.  On my Lucid which
is up to beta 1 now, uses about 10% of the cpu. If I get Firefox to look
at a busy web page it goes up to around 40%.

If your seeing 100% try turning off the laptop and then turn it on
again and quick look at the cpu usage. Now watch the most cpu used by
the list below the cpu data. Is any of them using more than 10% of the cpu?

73 Karl

= = = = = = =

Thanks for that Karl

I should probably have mentioned that I did 'top' and found that just
running Firefox takes ~12% when opened to my Gmail, which I figured as
probably fine-ish (thanks for confirming). I was initially worried that this
might be a Firefox thing and re-installed it too. But no luck. And now of
course, it's happening with any just about anything. Opening up Openoffice,
a PDF and Firefox gets dangerous... but not consistently though. I'd say
(very roughly) about 1 in 3 times the CPU runs away and then freezes my
machine.

I couldn't (and still can't) see any other jobs/processes that are sucking
up the CPU. I'm still running on the assumption that this isn't hardware,
but not knowing much beyond the absolute basics of CPUs means I'm really
stuck here. Urgh! The love of Ubuntu is not strong with me today.

= = = = = = = =

What you haven't said, yet, is have you tried looking at any other causes??

Yes, your problem could be a CPU.  Or it could be a kernel update.

But before you go down that dark path, you need to look at other
things first.  You said you've had this system for a year or so... are
you sure the fans are working and it's not over-heating?  Are you sure
the case isn't full of dust, fur, or other things that shouldn't be in
there?

Have you tried running memtest86 to test the RAM?  So far, all the
things you mention sound a lot like over-heating or bad memory.

Unfortunately, your problem is a lot like the medical diagnosis "I
feel bad".  It could be caused by a LOT of different things, and your
best bet is to eliminate the most common things first.

0:  Boot from a live CD or USB stick.  If you run the live environment
that way, do you still see high usage?
1:  Dirty computer.  Clean it out.
2:  Dead cooling fans.  Replace them.
3:  Bad RAM: test it and replace as necessary
4:  at the very least, reseat your ram.
5:  Other things??

You said this is a laptop, and if it's only a year old, I very
strongly doubt the processor is bad.  It COULD be bad, but if your
processor was so bad off in the first place that it would start
failing after a year, you would have seen problems long before now.

Cheers
Jeff

 = = = = = = =

There have been a number of comments on this line, but the bottom line
is this: high CPU usafe is a software issue, it is not a hardware
problem. If you drive everywhere at 10mph over the speed limit and
keep getting speeding tickets, it is not because something is wrong
with your car's engine.

If your CPU was overheating, it might thermally throttle itself down
to a slower speed, resulting in poor performance - but that does not
mean the CPU would be at full usage all the time. The primary symptom
would be a very unresponsive, slow & sluggish PC.

You should be looking for background processes that are running and
taking all the CPU bandwidth, not for hardware problems... although a
regular good clean of the inside of your machine is always a good
idea!

Liam

= = = = = = = =

Thanks Jeff and Liam

Jeff, yup when I ran my DELL hardware test I ran everything from fan tests
to RAM. So all good there we hope.

I'm really not seeing any particular process causing the problem, and also
seem to feel that I can't make a convincing argument for hardware being the
issue. I suppose my concern is that there's been an update that has somehow
buggered things up. But surely Canonical/Ubuntu check this on a laptop
they've agreed LTS on?

Any other words of wisdom on what next to do?

Thanks,
Quin

= = = = = = = = =

Would it be reasonable to ask you to explain better?
"CPU runs away and then freezes my machine" (for how long it runs away and
how you see it). Why can't you see the processes running in that time (with
watch top, for instance) but you can see the cpu running away?. Does the
laptop freezes? So, how you see it? Too short time, not conclusive, I think.

It happens if you don't run firefox? May be a problem with an add-on?

Sorry if you already answer that.

I mean, Does the laptop freezes immediately after the CPU goes mad? :)

Luis

= = = = = = = = =

Well, if you're sure it's not hardware (and I really doubted it in the
first place, I just like to rule out the easy things when things like
this happen) then that only leaves software... ;-)

Now that I think about it, I may have seen something very similar to
what you're seeing, but to be honest, it's been a good while since I
ran Hardy...  I did run it for quite a while on a Thinkpad, and
thinking back, every time I ran into a problem like this: inexplicable
CPU load, system freezing, etc, it was almost always due to something
using Java.

In my case, either Firefox running pages that had java applets, or
java programs (we had a couple that were used for front ends to
databases, ticketing system, etc).  Lotus Notes also caused quite a
bit of pain for me too.

The best thing I can tell you at this point is make sure everything is
up to date (I have a feeling it is, going by your responses so far),
and pay a LOT of attention to what you're doing at the time this
happens.

Also, maybe something here will give you an idea:

http://www.cyberciti.biz/tips/top-linux-monitoring-tools.html

vmstat could be useful, at least it will give you an idea of what
state the CPU is in at any given moment and show idle, system usage
and user-land usage so you can determine if it's a user app or a
system app that's causing the problem.

I'm still thinking it's gotta be something Java related.  Despite all
the people (java developers) who swear by the superiority of Java, I
still despise java code for this very reason...

Cheers
Jeff

= = = = = = = = =

Thanks Luis and Jeff

Yup, Luis, this isn't a Firefox specific thing, and it is a case it being
fairly random and quite sudden (spike to 100% and system freezing seconds
later).

That link's great thanks Jeff. I could be kidding myself but I might have
been running something java-esque any time this happened. Hmmm, perhaps
that's it.

Right... back to the drawing board.

Quin
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