Dedicated processing on SP2 or SP4? Need answer

[John Sasso]

I have a question about running single-CPU jobs for dedicated processing
on a multiprocessor IBM SP2 or SP4.

QUESTION: Can an application be run as dedicated and non-shared on an
SP2 or SP4 run 100% dedicated from start-to-finished on a CPU without
EVER being process-swapped (context-switched) by another process, in
particular a process that runs as root (e.g., the scheduler, some
maintenance daemons, etc.), even if the duration of the
swap/context-switch is very small? In addition, will such a process
have access to the CPU's ENTIRE cache so there'd never be a concern
about another process (even a high-priority root process) using the same
CPU's cache? (Assume the program the user runs in question is one that
uses static arrays and does not do any file I/O or I/O to stdin/stdout).

I've heard of the use of processor affinity for running programs in
so-called dedicated, non-shared mode, but I need know know if processor
affinity or some other mechanism on the IBM SP2 or SP4 would allow a
user process to run absolutely 100% dedicated, without EVER being
context-switched by ANY process or thread whatsoever, on a CPU, nor be
interrupted by any type of system interrupt (e.g. network I/O).

Any supporting docs you can provide would be great. Thanks!

-john


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[Cydrome Leader]

Post by John Sasso
I have a question about running single-CPU jobs for dedicated processing
on a multiprocessor IBM SP2 or SP4.
QUESTION: Can an application be run as dedicated and non-shared on an
SP2 or SP4 run 100% dedicated from start-to-finished on a CPU without
EVER being process-swapped (context-switched) by another process, in
particular a process that runs as root (e.g., the scheduler, some
maintenance daemons, etc.), even if the duration of the
swap/context-switch is very small? In addition, will such a process
have access to the CPU's ENTIRE cache so there'd never be a concern
about another process (even a high-priority root process) using the same
CPU's cache? (Assume the program the user runs in question is one that
uses static arrays and does not do any file I/O or I/O to stdin/stdout).
I've heard of the use of processor affinity for running programs in
so-called dedicated, non-shared mode, but I need know know if processor
affinity or some other mechanism on the IBM SP2 or SP4 would allow a
user process to run absolutely 100% dedicated, without EVER being
context-switched by ANY process or thread whatsoever, on a CPU, nor be
interrupted by any type of system interrupt (e.g. network I/O).
Any supporting docs you can provide would be great. Thanks!
-john

What's an IBM SP4?

[c.p. moderator: John for a 1-line question like that, please cut the
original attribution down and not use the entire text body.]

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