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List:       kde-devel
Subject:    Re: Again: Help from someone with an SMP system needed
From:       Geert Jansen <g.t.jansen () stud ! tue ! nl>
Date:       1999-03-02 15:58:01
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Chris Schlaeger wrote:
> I'm getting reports from some people that the KTop load meters for SMP
> processors show all the same load history. Others seem to have no
> problems. Since I have no SMP machine to test this I need someone who
> can checkout the latest KTop from kdeutils/ktop and test this. Either
> the Linux scheduler is really good in balancing the load or KTop still
> has a bug.


Hi Chirs,

I don't think there is a bug here. I just tested Ktop on my SMP system
(2xPII).

First, I fired up one cpu bound process and the load went to 1: ok. Both
processors showed about 50% of usage so that's ok too. The load histories
were similar but not identical. Under Linux, there is a penalty for a process 
changing CPUs and on an unloaded system this should not happen.
But it is perfectly normal when running a lot of programs, like under X.

I also checked this with /proc/stat: both CPUs accumulated time so if there's 
a bug, it's in the Linux kernel :)

When I fired up a second cpu bound process, the load in ktop went to 2 and
both CPUs were 100% busy. Everyting OK here too.

Nice work, by the way! Ktop looks good. A few years ago I also programmed a
Linux only, ncurses text mode system monitor. I called it hifs and you can still 
find it on skynet.stack.nl/pub/linux/hifs. Some things I did:

* CPU usage was not calculated only over the last sampling period, e.g:
100 * ticks_used/ticks_elapsed, but it was a weighted average over the last
4 periods. I took an exponential decay as the weighting function. This
gives smoother numbers for processes that last longer than a few sampling
period. 

* I added a statusbar where messages were shown. For example, I checked
mounted filesystems for free space and reported an error there if they
became full. You could also put syslog messages there.

* Hifs allowed you to kill/renice/write to certain processes.

These are just some thoughts. Maybe they are usefull for you.

Greetings,
 --
    Geert Jansen,                                email: <geertj@stack.nl>
    (future) Phylosopher and Physicist             PGP key ID: 0xD2B5E7CE

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