On Tue, 12 Feb 2008, steve szmidt wrote:
> On Tuesday 12 February 2008, Eben King wrote:
>> Something's using up CPU time on my machine, but nothing shows in top nor
>> gkrellm's strip charts, nor does any unusual network use show up in
>> gkrellm. But bash and trn take seconds to start and exit, and the CPU speed
>> is a constant 2.4G (normally it falls back when nothing's happening). How
>> can I find out what it is? I can get network bandwidth from the
>> internet-facing router for everyone combined (which is mostly me), for
>> periods from 1m - 5h.
>
> If an application does not thread and ties up some h/w you also get these
> dragged out delays. A similar thing can be seen with the desktop. Start
> something which opens a login or confirmation window and leave it alone.
> Other confirmation windows ends up in a queue waiting for the first to be
> cleared.
>
> Windows does that on boot when it looks for drives. It will sit and time out
> on every drive, rather than running multiple threads and do all drives.
I think parallelizing bootable drive checking would require a threaded BIOS.
Much more complex and hence buggier.
> When you say it's using up your CPU how do you identify this?
Well, given that top doesn't lie it must not be that. Maybe something's
hogging a vital syscall?
eben@pc:~$ time xterm -e bash -c exit
real 0m5.029s
user 0m0.011s
sys 0m0.005s
Try it on your machine. It should take way short, maybe <0.1s.
trn-in-an-xterm takes a long time to start also. The CPU speed is pegged at
max, but that's because cpufreq_ondemand was set up improperly. (It's fixed
temporarily now, but should I just put the commands into rc.local or is
there some holy Debian way?)
> Often times a machine look like it has locked up but is actually in some deep
> processing which is using up some resource making the desktop appear locked
> up.
Few things have failed outright ("rxvt -e true" and "rxvt -e :" hang, but
"rxvt -e bash" works eventually), they're just slow starting. Can't think
of something I have which puts a load on the CPU during operation. Some
games stress the GPU.
--
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