Re: add /proc/sys/kernel/cache_decay_ticks

[David Mosberger <davidm@napali.hpl.hp.com>]

>>>>> On 19 Jun 2003 00:05:18 +0200, Andi Kleen <ak@suse.de> said:

  Andi> David Mosberger <davidm@napali.hpl.hp.com> 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.

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

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

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

I don't see why the two have to be tied together.  I agree it would be
_nice_, but having /proc/sys/kernel/cache_decay_ticks in it's current
form is much better than nothing at all.

	--david