Sorry, I know this is a little left-field, but how about redesigning your
process so that instead of using a load_avg, you start all your calculations
from a single server on each node? It could queue up incoming calculations,
and fork a child to do each one.
Of course, it would catch a signal when the child died, so you'd immediately
know when to start up another calculation. If you liked, it could check the
one-minute load avg from time to time to see what would be a friendly level of
calculations overall, adjust the overall level of concurrent child processes
accordingly.
The timing, however, would still come from a signal, and would thus be
instantaneous.
Or am I being totally dumb?
Sean
On Sun, Nov 05, 2000 at 07:55:40AM -0500, bobyetman@att.net wrote:
>
> I'm working a project a work that is using Linux to run some very
> math-intensive calculations. One of the things we do is use the 1-minute
> loadavg to determine how busy the machine is and can we fire off another
> program to do more calculations. However, there's a problem with that.
>
> Because it's a 1 minute load average, there's quite a bit of lag time from
> when 1 program finishes until the loadavg goes down below a threshold for
> our control mechanism to fire off another program.
>
> Let me give an example (all on a 1-cpu PC)
>
> HH:MM:SS
> 00:00:00 fire off 4 programs
> 00:01:00 loadavg goes up to 4
> 00:01:30 3 of the 4 programs finish loadavg still at 4
> 00:02:20 load avg goes down to 1, below our threshold
> 00:02:21 we fire off 3 more programs.
>
> We'd like to reduce that almost 50 second lag time. Is it possible, in
> user-space, to duplicate the loadavg calculation period, say to a 15
> second load average, using the information in /proc?
>
> The other option we looked at, besides using loadavg, was using idle pct%,
> but if I read the source for top right, involves reading the entire
> process table to calculate clock ticks used and then figuring out how many
> weren't used.
>
> Ideas, opinions welcome. Yes, I read the list, so either respond direct
> to me, or to the list.
>
> bobyetman@att.net (Robert A. Yetman)
>
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