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Re: cronjobs and top not getting along

charles@lunarmedia.net wrote:
> >
> > That error is because top can't figure out what sort of terminal the
> > cron session is in, because it isn't in one.  So top gets confused
> > trying to figure out how to clear the screen and stuff.  The proper
> > approach would be to look at top's sources and figure out how it
> > computes the numbers.  It's somewhere in the /proc files, I'm just not
> > sure which one(s).
> >
>         yeah, i have waded through /proc looking for where top
>         gets the actual percentage number and it just isnt there.
>         i am suspecting that top takes another number from within
>         /proc file and generates an actual xx% value.
>         anyone else have ideas on how to get a % value out of a
>         /proc file? I know there must be some way since there are
>         all those grovvy little applets for WM that do essentially
>         what I want but from a gui

Well, looking through the sources for kpm, it takes two readings from
/proc/stat (the first line is CPU numbers for user/nice/system/idle in
that order).  The it subtracts the two values like so:

181     int user = Procinfo::cpu_time[Procinfo::CPU_USER]
182                - Procinfo::old_cpu_time[Procinfo::CPU_USER];
183     int nice = Procinfo::cpu_time[Procinfo::CPU_NICE]
184                - Procinfo::old_cpu_time[Procinfo::CPU_NICE];
185     int system = Procinfo::cpu_time[Procinfo::CPU_SYSTEM]
186                  - Procinfo::old_cpu_time[Procinfo::CPU_SYSTEM];
187     int idle = Procinfo::cpu_time[Procinfo::CPU_IDLE]
188                - Procinfo::old_cpu_time[Procinfo::CPU_IDLE];

Then it does a couple calculations:

196         float tot = (float)(user + nice + system + idle) / 100;
197         s.sprintf("cpu %.1f%% user, %.1f%% nice\n%.1f%% system,
%.1f%% idle",
198                   user / tot, nice / tot, system / tot, idle / tot);

That should do it.

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