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Old 01-22-2009, 12:10 PM   #1
jlinkels
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Debian: top process under user root uses all CPU time


Debian Lenny KDE 3.5.9
Kernel 2.6.26

Sometimes my desktop computer becomes very sluggish. Often it is famd or Opera responsible for this. Anyway, I run 'top' a lot of times. Today I did that again and this is what I saw:

The top process started by user root is using over 90% of all CPU time. Then top is not that useful anymore.
http://pdis.rnw.nl/~hansl/links/top1.jpg
That is weird, but root was not even logged in at that time, which makes it even more weird. See below on the picture.

After logging in as root and killing the process everything was back to normal. No suspicious entries in auth.log.

I have two more problems which occured over the course of time:
- after a few days both of my scanners become very, veeeeeeeeeeeeeeery slow. Replugging doesn't help, rebooting does.
- at random times, my network is gone and I have to restart my network. This can happen within 12 hours of a reboot, or in 12 days. After a reset of the network the period is as random, but sometimes it can happen several times on one evening.

Sounds like a HW problemm BUT... at home I am running Debian Lenny as well, and since dec 29 2008 I see exactly the same behaviour that I have to reset the network regularly.

And now this with the top process...

Don't ask me what I installed the past few months and what not. Of course I install Debian programs now and then, with associated dependencies. Bot the office machine and home machine have identical packages installed, have an identical NIC (3C905) and one scanner is identical (Canon LiDE 25)

Any other Debian user seen this weird behaviour?

jlinkels
 
Old 01-22-2009, 12:39 PM   #2
jhwilliams
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I wouldn't be alarmed by the cpu usage of top, so long as it doesn't stay up there. It is expected that processes, while on the CPU, will utilicize it well. At a particular polling instance, top may be running its backend slice, and sure, it'll be doing some work. Does top sustain that level for a while, or just appear at the top every now and again? Also, it has been widely argued that top is not the most accurate monitoring utility, in particular when it comes to memory usage (see the internetz 4 more details.)
 
Old 01-22-2009, 01:22 PM   #3
jlinkels
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I know how top behaves, usually it shows some bursts. But it stays there put. Using 80-95% CPU time, dependent on what the other processes leave, and for more than a few minutes. And I cannot understand why it runs as root account while root wasn't logged in.

jlinkels
 
Old 01-22-2009, 01:48 PM   #4
jhwilliams
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Quote:
Originally Posted by jlinkels View Post
I know how top behaves, usually it shows some bursts. But it stays there put. Using 80-95% CPU time, dependent on what the other processes leave, and for more than a few minutes. And I cannot understand why it runs as root account while root wasn't logged in.

jlinkels
hm, odd indeed. (didn't mean to baby you on a generic top/scheduler rant, i see that you have "been around!") sorry not to be of any more help.
 
Old 01-22-2009, 02:19 PM   #5
jlinkels
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No offence taken, I just a bit stressed
 
Old 01-22-2009, 03:46 PM   #6
almatic
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it looks like an old top process (maybe a crashed one), not the one that is visible (look at the cpu time).
As for myself, I haven't seen any unusual behaviour of top. I have, however, had the same problems with famd. Fam annoyed me with cpu usage and unnessary blocking of ressources (which prevented unmounts and so on), so I replaced it with gamin. Gamin runs fine and hasn't shown any such behaviour so far.
 
Old 01-22-2009, 04:06 PM   #7
salasi
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hmm, I haven't seen that behaviour (and top seems to be better behaved in difficult circumstances than ksysguard). However I note that recently I seem to have switched from 'top' to 'htop' without having a very clear reason for doing that, apart from that the display seems 'friendlier'.

So one question that you might like to answer is does htop do the same thing as top?
 
Old 01-22-2009, 09:02 PM   #8
jlinkels
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Quote:
Originally Posted by almatic View Post
it looks like an old top process (maybe a crashed one), not the one that is visible (look at the cpu time).
Well, of course I don't have an how long it has been running. But when I started it as root, and logged out, the process should have been stopped, shouldn't it? There might have been an error in the process, but I was able to kill it with a normal kill, not kill -9 or so.


Quote:
Originally Posted by almatic View Post
Fam annoyed me with cpu usage and unnessary blocking of ressources (which prevented unmounts and so on), so I replaced it with gamin. Gamin runs fine and hasn't shown any such behaviour so far.
Yes, I know all about famd. That is the reason that I use top so often. To see if any non-responsiveness comes from famd. Thanks for the advice on Gamin.

Quote:
Originally Posted by salasi
So one question that you might like to answer is does htop do the same thing as top?
Couldn't tell you what htop does. It is not reproducable. After I killed this one, the next top was fine. Popped up now and then with 1% CPU usage or so, quite normal. It is the first time in 9 years that I see top go berserk Will give htop a try to see what it is. Thanks for recommending.

Maybe this is just the next step to a detoriationg system. No, I am not wanting to reinstal this system. I installed it in 2004 already and upgraded it ever since, it is not Windows. Although... since New Year I already restarted the machine twice. I used to do that twice a year.

jlinkels
 
  


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