On Mon, 10 May 1999, Pavel Machek wrote:

> > that only 0.3% CPU time is spent in the kernel. (readprofile shows
> > that
> 
> This is bogus. [...]

oops, right. Anyway, vmstat shows that about 200 reschedules per second
happen with 200 running processes:

 r b w  swpd  free  buff cache  si  so   bi   bo   in   cs  us  sy  id
200 0 0     0 156248 274668 26340   0   0    0    0  109  215  99   1   0
200 0 0     0 156248 274668 26340   0   0    0    0  109  215  99   1   0
200 0 0     0 156248 274668 26340   0   0    0    0  108  215  99   1   0
200 0 0     0 156248 274668 26340   0   0    0    0  109  217  99   1   0
200 0 0     0 156248 274668 26340   0   0    0    0  108  215  99   1   0
200 0 0     0 156248 274668 26340   0   0    0    0  109  215  99   1   0
200 0 0     0 156248 274668 26340   0   0    0    0  108  215  99   1   0

a reschedule every 5 msecs is not a big overhead at all, considering the
_ridiculous_ CPU load. 

>            [...] Scheduler is highly unlikely to measure _its own_
> overhead. Basically, do not trust this meters this much. Take a look
> at how scheduling is done - it is in sync with timers which measure
> who eats time -> it is highly unreliable.

you are right, i just knew it's not much overhead and quoted the first
number available, mea culpa :)

-- mingo


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