Clarification on benchmark results

Posted May 28, 2008 17:55 UTC (Wed) by keithw (guest, #3127)
Parent article: GEM v. TTM

Note that the benchmark results I posted don't exactly show what is claimed in the article.

In particular, the version of the driver labeled "i915tex" is the original TTM version of the
i915 driver and has good performance, while "master/ttm" is a newer one which seems to have
suffered some degree of performance regression relative to both i915tex and the original
non-ttm version...  at least in the couple of machines I've looked at...

To make things even more confusing, it seems that Keith Packard's testing may have revealed
yet another regression in the non-ttm versions of the driver, which I haven't had a chance to
dig into at this point.  

All this testing is pretty preliminary & hampered by lack of time & travel schedules, etc.
So, nobody really has all the answers.

Anyway, the biggest win at this point would be getting some sort of a memory manager interface
that everyone agrees on & can move forward with, *providing* that it doesn't encode design
decisions which preclude a properly performant implementation -- and I'm hopeful that's the
case.

Keith

Clarification on benchmark results

Posted May 30, 2008 20:40 UTC (Fri) by drag (guest, #31333) [Link]

This may be one of those situations were you just are not going to know the right way to do
it. 

Like the Linux developers stumbling over themselves to deal with wireless drivers.. First they
treated them as generic ethernet devices, which ment that each driver had to do way to much
work on it's own. 

Then Intel introduced their open source 802.11 stack, unfortunately it was not generic enough
to work with all sorts of different drivers.

Now they finally got the devicescape stuff fairly down so that it makes writing Linux wireless
drivers a sane thing to do.

Who knows? It may just be that a Intel video card vs Nvidia/ATI card are so different
architecturally that they simply can't be managed with the same API and that maybe Nvidia and
ATI cards can be managed together or something like that.

How can you tell? The only two ways I can figure it out is wait years and years and end up
with half-made drivers supporting obsolete hardware, or just to go for it and know it's going
to be a learning experience and get something done quick enough that it can actually benefit
end users.