Subj : Re: Solaris real-time thread capabilities
To   : comp.unix.solaris,comp.programming.threads
From : Greg Menke
Date : Wed Sep 07 2005 09:46 am

Logan Shaw <lshaw-usenet@austin.rr.com> writes:

> Casper H.S. Dik wrote:
> > capnwhit@yahoo.com writes:
> 
> >>Hello Eric, Thanks a lot for your reply! Code sample coming up... I
> >>basically kept track of the maximum latency between t1 and t2 (as shown
> >>in my while loop on my initial post)... the average latency was about
> >>1000 ns (over a 5 minute period) but the max latency was 323,000,000!
> >>I'll post the sample code shortly...
> 
> > Well, *that* is not impossible.  That's because your program was
> > hit by a context switch and other processes got to work for apparently
> > a lengthy period of time; and if that meant that you later induced a
> > page fault, 300ms could easily be explained.
> 
> I puzzled over this for a while.
> 
> If he creates a processor set and puts his program as the only process
> in that set, and if he makes his thread realtime class and sets the
> priority to the maximum, and if he sets that processor to no-intr state,
> then how can another thread preempt that thread?
> 

The OP has not yet proven that his program is bug-free and not making
incorrect assumptions.  Its more likely the problem is there than in the
scheduler.

I ran his test program which he says demonstrates the problem, after
correcting some math errors and getting rid of the printf inside his
inner loop, I found no particular scheduling jitter when running it as
an RT task on the default processor set along with everything else-
including running Openoffice, Acrobat, mozilla, emacs, etc..

Gregm

.