Hello Tim, All,
Apparently, my problem was heating related. My laptop is sitting on
a table with an uneven plastic table cloth, and since I raised it
slightly up from the table by putting bottle caps under the rear feet,
I have not experienced any problems any more.
The connection between heat and sluggishness was not that obvious.
Before the raising, I had installed temperature displays, and when I
run at full load, the temperature would first go up to 90-something,
then fall again, and only after that it would start to slow down. If
the slowing down is from a deliberate slowdown to decrease
temperature, the response seem to come too late and to strong.
Take care
Oliver
On Wed, Apr 1, 2009 at 12:00 PM, Tim <ignored_mailbox@xxxxxxxxxxxx> wrote:
> Tim:
>>> Is the CPU cooling still working fine? Overheating can cause slowdowns.
>
> Oliver Ruebenacker:
>> Interesting! How can I test this?
>
> Does the fan move air well, is it clogged, can you visually inspect it,
> does the temperature change if you *VERY* *BRIEFLY* block airflow.
>
>> Do you know what mechanism causes the slowdown?
>
> Most modern CPUs have a temperature sensor. As a self preservation
> exercise, many will slow down operations if they start to get too hot,
> as that will reduce the amount of heat the CPU produces.
>
>> Is it consistent with showing high CPU usage?
>
> If the CPU is doing a lot of work, or running fast (for those that have
> speed control), it will generate heat. The more work and speed, the
> more heat. Also, in one of life's peculiarities, if slowing down the
> CPU means it takes significantly longer to get the job done, slowing it
> down mightn't be the life saver that it's supposed to be, as it may
> still get hot enough, for long enough, to be a problem.
>
> With really inadequate cooling, you can fry things in mere seconds. I
> got quite worried when my laptop suddenly went nuts the other day, for
> no good reason. Typically, it's running around the 50 degree mark for
> both CPU and graphics processors, but it surges depending on the work
> load, often to around 60 (it used to be about 5-10 degrees less, and I
> can reproduce that by swapping the hard drive for the old one that still
> has Fedora 7 on it). I loaded up some webpage, and it rapidly
> skyrocketed to 80, the fan turned on hard, and some rather nasty smells
> emerged. I'm guessing plastic nearby the hotspot, or heatsink material.
> I killed the Firefox web browser smartish, and it settled down to a
> reasonable temperature within a few seconds. No the vents were not
> blocked, and I have checked for things that might clog airflow.
>
> It strikes me that many laptops are very poorly designed, with air
> intake vents on the bottom, that will be blocked if you actually do use
> it on your lap.
>
>> Actually, I also felt sometimes that my laptop was quite hot, long
>> before I had slowdown issues. And sometimes the fan would seem to gear
>> up, even with no one using the laptop.
>
> Mine used to run quite cool and quiet, but not since Fedora 9. Just
> sitting at the logon screen its churning away. So I have yet another
> thing I don't like about the new GDM (it's not just spinning the fans
> more than needed, they're expelling quite a bit of heat).
>
> If I logon and do nothing, it cools down a bit, sometimes enough that it
> runs nearly silently; but that's rare, these days. But, if I leave it
> alone, and it's idling just showing the empty desktop (no applications
> running), sometimes it'll suddenly warm up. And it's not like a cron
> job has kicked in, there's no indication of that if I leave top running.
>
> --
> [tim@localhost ~]$ uname -r
> 2.6.27.19-78.2.30.fc9.i686
>
> Don't send private replies to my address, the mailbox is ignored. I
> read messages from the public lists.
>
>
>
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--
Oliver Ruebenacker, Computational Cell Biologist
BioPAX Integration at Virtual Cell (http://vcell.org/biopax)
Center for Cell Analysis and Modeling
http://www.oliver.curiousworld.org
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