Re: [PATCH] sched.c: Be a bit more conservative in SMP



Antonio Vargas wrote:
A variant on this theme would be (not tested or somewhat, just a
random idea for considering):

1. find if the process is a cpu-hog, if not then ignore

2. find somehow how much time has this process on it's current cpu

3. then, instead of always substracting 1 from th current load on the
current cpu, substract for example 1...0 when running from 0 to 60
seconds... this way cpu hogs would only rotate slowly?

in code:

number_to_sub_from_queue_load = (256 - min(256,
time_from_last_change_of_cpu)) >> 8;

somehow managing to get fixedpoint loadlevels on the runqueues would
make this work better....


Yes ! That might be a better idea !
In fact, I tested the 1st patch on our cluster (Finite elements computing on 8 CPUs):
- Under Windows: 875 seconds
- Linux 2.6.16 : 1019 s
- Linux 2.6.16 + manual taskset : 842 s
- Linux 2.6.16 + Vincent's patch : 1373 s :-(

If you find time to write a patch, Antonio, I would be pleased to try it !

Cheers,

--
Ludovic DROLEZ
http://lrs.linbox.org - Free asset management software
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