Re: [PATCH for 2.5] preemptible kernel

[Nigel Gamble]

On Thu, 22 Mar 2001, Rusty Russell wrote:
> Nigel's "traverse the run queue and mark the preempted" solution is
> actually pretty nice, and cheap.  Since the runqueue lock is grabbed,
> it doesn't require icky atomic ops, either.

You'd have to mark both the preempted tasks, and the tasks currently
running on each CPU (which could become preempted before reaching a
voluntary schedule point).

> Despite Nigel's initial belief that this technique is fragile, I
> believe it will become an increasingly fundamental method in the
> kernel, so (with documentation) it will become widely understood, as
> it offers scalability and efficiency.

Actually, I agree with you now that I've had a chance to think about
this some more.

Nigel Gamble                                    [e-mail]
Mountain View, CA, USA.                         http://www.nrg.org/

MontaVista Software                             [e-mail]