Invalidating TLB, cache

[Eric W. Biederman]

Li-Ta Lo <ollie at lanl.gov> writes:

> Eric,
> 
> What was the conclusion of invalidating the cache and TLB ?
> If found that
> 
>         xorl    %eax, %eax
>         movl    %eax, %cr3    /* Invalidate TLB*/
> 
> still exists in the current CVS.

Cache invalidates are actively harmful, as they can loose data that has
not been written from the cache and they take seconds on an Opteron
to execute.

Currently TLB invalidates don't have any negative side effects and
seem harmless.  Since TLB do not cache writes I can't think of a case
where they would cause incorrect behavior.    If they start running
slow on some we can revisit the issue.

Eric