[Sussex] Bad motherboard or processor?

[Steve Dobson]

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Hi John

John Crowhurst wrote:
> I have a hardware question, since my new laptop works like a dream on Linux.
> 
> My main machine has a problem:
> 
> 1. I can type and not see the text on the screen, then it gets over its
> senior moment and empties the keyboard buffer to the screen.
> 2. Videos freeze for a short time and play again.
> 3. Youtube videos glitch and play from the start.
> 
> I've never seen a bad processor, so I've no experience of when one goes
> bad. Its usually motherboard.
> 
> The machine had a bad CPU fan, one of those supposedly quiet ones that
> ended up touching its blades on the heatsink and promptly failing to
> start.
> 
> What would I experience if my processor was on the way out, and does
> anyone have any idea as to why the motherboard is having senior moments.
> 

I have a simular "problem" with my Acer Aspire One laptop.  It's main
"disk" is a flash storage device and it's write performance is sloooow.
 This is most noticeable with the web browser, which tends to lock up
when it is downloading a new page.  While I haven't investigated it
fully I have reasoned that it the writing of the downloaded data to the
disk caches that is the cause of the problem.  But I also see hesitation
when saving files in Emacs or when running LaTeX or other local
processes that use the local disk.  The problem isn't as bad when I am
using the faster SD storage devices.

I don't see much of this problem with local processes that don't use
much disk IO.  Thunderbird for example as all my emails are remotely
held and access to them is via IMAP.  I also don't see any problem when
I am using the Acer as a remote display device.  i.e.  I am running a
program on my workstation but displaying the windows on the Acer.  Added
to that that the "local disk light" is on when it locks up is how I
figured out what is going on.

While I accept this on my Acer, because it has a slow flash storage
device, I would never accept it on a workstation or server which used
standards disks.  These days even laptop disks are fast enough that
local IO is almost invisible.

I would recommend that you take a look at the system logs
(/var/log/syslog) and look for any kernel messages from the disk
subsystem complaining about interrupt timeouts or commands not being
completed or that kind of thing.  If you see any stop using the system
and go and buy a external disk and back the system up TODAY!

If you don't see anything then you might like to look at some of the
performance monitoring tools.  Look for processes blocked on IO.
Assuming that you main machine is a workstation and it is more or less
dedicated to you and what you are going then there shouldn't that many
processes doing IO except when you tell them too.

I'm afraid that this sort of system "tuning" is a bit of a black art.
You need to have a feel for what the system should be doing and there
are a number of different tools available and which ones are most
suitable for you depends mostly on you.

Steve
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