Re: [RFC] per-cpu preempt_count

From: H. Peter Anvin
Date: Mon Aug 12 2013 - 13:53:54 EST

On 08/12/2013 10:35 AM, Linus Torvalds wrote:
> Agreed. Making it atomic would suck, and cancel all advantages of the
> better code generation to access it. Good point.
> And yeah, it could be two variables in the same cacheline or something.

So we would have code looking something like:

decl %fs:preempt_count
jnz 1f
cmpb $0,%fs:need_resched
je 1f
call __preempt_schedule

It's a nontrivial amount of code, but would seem a fair bit better than
what we have now, at least.


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