Dear all,

My first question has been answered, thnx a lot!!!

Now, to solve the load problem i've noticed that the program uses a
tight for(; loop, effectively spinning as hard as possible, whilst
not needed (explaining the cpu hogging). Now, I could use e.g.
sleep(), nanosleep() etc, but these seem to have side effects, either
not actually sleeping or very course sleep intervals. Is there some
kind of yield() that allows me to do just one for(; loop and then
relinquish the remainder of the time slice allocated to the app?

e.g.:

for (;
{
dosomething();
yield_rest_of_timeslice();
}

Thnx

Max

On Feb 11, 10:58 am, TheMaxer <m...@max-irene.demon.nl> wrote:
> Dear all,
>
> My first question has been answered, thnx a lot!!!
>
> Now, to solve the load problem i've noticed that the program uses a
> tight for(; loop, effectively spinning as hard as possible, whilst
> not needed (explaining the cpu hogging).
[snip]
> Is there some
> kind of yield() that allows me to do just one for(; loop and then
> relinquish the remainder of the time slice allocated to the app?
[snip]

Yes, sched_yield(2) (see "man 2 sched_yield")
.. . .

SCHED_YIELD(2) Linux Programmer's Manual
SCHED_YIELD(2)

NAME
sched_yield - yield the processor

SYNOPSIS
#include <sched.h>

int sched_yield(void);

DESCRIPTION
A process can relinquish the processor voluntarily without
blocking by
calling sched_yield(). The process will then be moved to the
end of
the queue for its static priority and a new process gets to
run.

Note: If the current process is the only process in the
highest prior-
ity list at that time, this process will continue to run after
a call
to sched_yield().

POSIX systems on which sched_yield() is available define
_POSIX_PRIOR-
ITY_SCHEDULING in <unistd.h>.

RETURN VALUE
On success, sched_yield() returns 0. On error, -1 is
returned, and
errno is set appropriately.

CONFORMING TO
POSIX.1-2001.

SEE ALSO
sched_setscheduler(2) for a description of Linux scheduling.

Programming for the real world - POSIX.4 by Bill O.
Gallmeister,
O'Reilly & Associates, Inc., ISBN 1-56592-074-0

Linux 1.3.81 1996-04-10
SCHED_YIELD(2)

On 11 feb, 19:33, Lew Pitcher <lpitc...@teksavvy.com> wrote:
> On Feb 11, 10:58 am, TheMaxer <m...@max-irene.demon.nl> wrote:> Dear all,
>
> Yes, sched_yield(2) (see "man 2 sched_yield")


Thnx Lew!

However, the process is the only one running, therefore sched_yield()
doesn't do something. A sleep() gives me the desired cpu load, but is
too coarse. I want something like, wake-up every 20msec or so and then
quickly dosomething() and sleep again....

Max

On 12 feb, 09:13, TheMaxer <m...@max-irene.demon.nl> wrote:
> On 11 feb, 19:33, Lew Pitcher <lpitc...@teksavvy.com> wrote:
>
> > On Feb 11, 10:58 am, TheMaxer <m...@max-irene.demon.nl> wrote:> Dear all,
>
> > Yes, sched_yield(2) (see "man 2 sched_yield")
>
> Thnx Lew!
>
> However, the process is the only one running, therefore sched_yield()
> doesn't do something. A sleep() gives me the desired cpu load, but is
> too coarse. I want something like, wake-up every 20msec or so and then
> quickly dosomething() and sleep again....
>
> Max

dear all,

It appears that nanosleep() is the way to go, after all. The issue
being that nanosleep() degrades to a busy waiting loop below certain
sleep values. This is ok from a nanosleep implementation point of
view.

I managed to change the app, so a bigger value for the sleep was
acceptable, making the app actually sleep between loop iterations.
Problem solved ;-)

Thanks.

Max