Re: [PATCH] Mantaining turnstile aligned to 128 bytes in i386 CPUs

On Wed, 17 Jan 2007, Suleiman Souhlal wrote:

> Bruce Evans wrote:
>> I haven't tried this, but have seen and partly worked sensitivity to
>> linear KVA maps not being physically (non)linear enough.  Some CPUs
>> and/or memory systems are remarkably sensitive to bank interleave.
>> FreeBSD's page coloring doesn't know anything about banks, ...
>
> About page coloring: Don't amd64 CPUs have virtually indexed, physically
> tagged caches? If so, wouldn't it make sense to turn off page coloring,
> since it's useless for virtually indexed caches (and probably hurts things
> a bit)?

I think superpages will soon turn off coloring.  Not sure if this is
right.  How is copying and zeroing a whole superpage at a time avoided?

IIRC, my benchmarks (and LMbench) show some small positive benefits for
page coloring on amd64.  I don't remember exactly what they are, just
that they are smaller than on AthlonXP.

Bruce