Subject: Re: aperture driver (Re: XFree 4.0)
To: None <>
From: Witold Wnuk <>
List: current-users
Date: 03/14/2000 01:02:09
On Mon, 13 Mar 2000, maximum entropy wrote:

> I built it from there and it seems to work fine.  But what exactly
> *is* "MTRR support"?  I'm not noticing any significant improvement in
> performance or anything else, while running X with this driver.

It is feature of newer Pentium CPUs that enables to assign different flags
to different areas of mem space. The most important is write combining. It
allows separate writes to be combined into burst transfers. It prevents
trashing caches too (by disabling them).

I did some tests and with VIA Apollo Pro Plus and Matrox G200
it is serious improvement. Something like 40MB/s without write combining
and 108MB/s with write combining. (painting directly to screen using DGA)

And yes, it is hard to notice difference with X.

        Witold J. Wnuk