Forcing processor affinity

[brudnakm]

All,

I am attempting to force process affinity using the

 sysmp(MP_MUSTRUN, cpu) ;

system call on an IRIX 6.5.11 Onyx 2. The problem is that as I observe process behavior using top and gr_osview the process does not run on the requested CPU. sysmp returns an error code of 0 (success) and "cpu" is well within range of the available CPUs. None of the CPUs are restricted or isolated. The process runs at a priority of +70 real-time. The process contains three threads (main blocks on I/O, second blocks on a message queue, third does the work).

My question: Is sysmp(MP_MUSTRUN, cpu) limited to single threaded processes only? How can I get all of my threads to run on the chosen CPU (I am already creating bound threads)?

Thank you,

Brudnakm.