Rob Browning writes:
> Assuming I understand you correctly, and this is a program of your
> own, add a call to nanosleep(2) at an appropriate point. You can tune
> the positioning and duration of the sleep to balance your needs.
> Note that what would be really nice here would be something like a
> "defer()" which just handed the rest of the processes timeslice back
> to the scheduler, but I don't know if such an animal exists. Perhaps
> nice(1) will get the same effect.
> The reason to prefer defer() to nanosleep() is that if there are no
> other processes that need to do useful work, you don't want to be
> sleeping.
How about sched_yield?
Look in sched.h
In the POSIX.4 book, page 170, it describes sched_yield as:
It moves the calling process to the back of the line for its priority,
allowing any other processes at that priority to run. Note that
sched_yield, when called by a priority 10 process, is not going to
allow a priority 9 process to run. Only another priority 10 process
would get a chance. If there were no priority 10 processes other than
the one calling sched_yield, then that process would immediately
resume its execution!
... {talks about a simple fork() example}
The point here is that sched_yield does something very simple. It
merely moves a process to the end of the queue for its priority level.
It does not guarantee that anything else is actually on that queue.
It certainly does not guarantee <i>what</i> is on the queue. For
example, some other process (unrelated to our sample program) might be
waiting to run - in which case, neither the parent nor the child would
be scheduled next. Therefore, don't use sched_yield to enforce a
particular scheduling order. It's too simple for that. Use
semaphores instead.
Hope this helps...
Jeff McWilliams
[EMAIL PROTECTED]
==
Jeff McWilliams ([EMAIL PROTECTED])
"The minstrel boy has gone to war,
in the fields of death you'll find him" - author unknown
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