Re: add /proc/sys/kernel/cache_decay_ticks

[Andi Kleen]

David Mosberger <[e-mail]> writes:

> /proc/sys/kernel/cache_decay_ticks allows runtime tuning of the
> scheduler.  The earlier patch collided with the C99-ification of the
> file, so here is a retransmit.

Funny, I did a similar patch for 2.4 a short time ago. But I would
suggest one change before you merge that to mainline. The variable
is currently used like this:

#define CAN_MIGRATE_TASK(p,rq,this_cpu)                                 \
        ((jiffies - (p)->last_run > cache_decay_ticks) &&       \o

Which means 0 means 1 jiffie. For a tunable it would be useful to be 
able to turn it off completely, which means the > needs to be replaced
with a >=. Unfortunately this requires changes in the architectures
too to subtract one. But it would make it more useful. I would do
the change before exposing it.

-Andi