Scheduling of processes, and timers

[Chris Torek]

In article <1991Jun13.141021.1 at sdl.mdcbbs.com> daniel at sdl.mdcbbs.com writes:
>... developed on Sparcstations running SunOs4.1, but should work on other
>Unix variants. ... Is scheduling likely to take place at system calls ?

Yes.

>        Is there a way round this if this is so ?

No (at least, not without major kernel changes).

>        Do I just give up and use gprof ?

Probably.  You can implement your own profiler; gprof is simply convenient
(see profil(2)).

> 2) The timer resolution on a Sparc 2 is 100Hz ...

This is purely a software issue on the SparcStations.  The actual timers
count in microseconds.  Of course, the software in question is the kernel;
you need kernel source to change it.

>        Is there any other timer available on Sparcstations ?

SparcStations have two timers, one intended for use as the scheduling
clock (often set to interrupt 100 times a second) and one intended for
use as a profiling clock (it interrupts at a much higher priority, and
can be set differently).  Ideally gprof will use the profiling clock,
running at a higher rate.
-- 
In-Real-Life: Chris Torek, Lawrence Berkeley Lab CSE/EE (+1 415 486 5427)
Berkeley, CA		Domain:	torek at ee.lbl.gov