🚀 go-pugleaf

In article <10847@polyslo.CalPoly.EDU> steve@polyslo.CalPoly.EDU (Steve DeJarnett) writes:
> Are there multiple run queues on a Balance 8000??  I've never studied the
> implementation of Dynix (lack of source makes it more difficult also :-), but
> I'd suspect there's one run queue, and processors grab the next job eligible
> when they're free.  Am I correct here??

I believe the BSD kernel maintains something like 30 run queues (Chris Torek
could probably give more accurate information).  The Dynix kernel is a pretty
close clone of the 4.2 kernel, so they probably have just as many.

I do know that Dynix maintains a queue (one per processor?) of jobs that have
been 'affinitied' to a processor.  The scheduler checks this queue before the
'normal' run queues.

> One last question.  When Sequent computes their load average, do they
> take into account the possibility that some of the processors might not have
> been available during the last 1,5,15 minutes??  If I have 2 processors running
> user processes, but the Sequent is basing its calculation of load average on
> 10 processors (or how many there actually are in my system), then a load 
> average based on that premise is not a truly representative number.

There are system calls available to find out how many processors are online
at the time of the call.  The kernel function that computes the load averages
(loadav in vm_sched.c) divides by 'nonline'.  If a processor goes offline,
the load averages won't be accurate, but after 15 minutes they will be.

--
Andy Rosen           | arosen@hawk.ulowell.edu | "I got this guitar and I
ULowell, Box #3031   | ulowell!arosen          |  learned how to make it
Lowell, Ma 01854     |                         |  talk" -Thunder Road
		RD in '88 - The way it should've been