Re: [9fans] faster vesa driver

[erik quanstrom <quanstro@quanstro.net>]

On Tue Jun  9 19:30:32 EDT 2009, me@acm.jhu.edu wrote:
> > On Tue Jun  9 17:20:12 EDT 2009, geoff@plan9.bell-labs.com wrote:
> >> I've just pushed out kernel sources and binaries to incorporate
> >> Aki's mtrr and vesa changes.  The combination makes monitor=vesa
> >> run quite a bit faster; we saw a factor of three speed improvement
> >> in one case.
>
> What got three times faster? Do you have some kind of tool to measure
> draw performance overall?

using andrey's screen saver hacks, i measured about an even greater
speedup using PAT, a technique similar to mtrrs but one that
uses page tables and not fixed physical ranges.  i did my tests with
andrey's xscreensaver hacks and timing catting large files to a fixed-sized
window.

i would attribute the perf difference between PAT and mtrr to be
a function of measurement and hardware — as in my crappy hardware.
if someone sees that one or the other is faster on the same hardware,
that would be very interesting to me.

- erik