Subj : Re: threads do not get cpa
To   : comp.programming.threads,comp.sys.sgi.misc
From : azb123
Date : Sun Aug 07 2005 09:21 am

Joe,
thanks for the suggestion!
I've added the following lines to my code:

if ((r=pthread_setconcurrency(nthreads)))
      fprintf(stderr,"Could not set concurrency: %d!\n",r);

The results are a little bit erratic, sometimes I get the expected
behavior, i.e. activity_in_top = nthreads*100, and sometimes I get less
than the expected activity. All this is on a SGI Octane with IRIX
6.5.24m (16cpus), no other applications running. I am little bit
puzzled now, could that be a strange effect of the IRIX scheduler?

I also noticed another oddity: When I run my program with more threads
it's slower than with just a single one, e.g.:

nthreads cpu-time wall-clock time
1             30         30
2            140         70
3            452        154

Do you have further suggestions?

Markus

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