Re: [patch] voluntary-preempt-2.6.9-rc1-bk4-Q5

Lee Revell
2004-08-31T20:14:50Z

On Tue, 2004-08-31 at 16:09, Ingo Molnar wrote:
> * Ingo Molnar <mingo@elte.hu> wrote:
>
> > it's more complex than that - MTRR's are caching attributes that the
> > CPU listens to. Mis-setting them can cause anything from memory
> > corruption to hard lockups. The question is, does any of the Intel (or
> > AMD) docs say that the CPU cache has to be write-back flushed when
> > setting MTRRs, or were those calls only done out of paranoia?
>
> the Intel docs suggest a cache-flush when changing MTRR's, so i guess
> we've got to live with this. _Perhaps_ we could move the cache-disabling
> and the wbinvd() out of the spinlocked section, but this would make it
> preemptable, possibly causing other tasks to run with the CPU cache
> disabled! I'd say that is worse than a single 0.5 msec latency during
> MTRR setting.
>

File under boot-time stuff, I guess. This could be bad if X crashes,
but I can't remember the last time this happened to me, and I use xorg
CVS.

Lee