Re: Unable to continue testing of 2.6.25

[Andi Kleen <andi@firstfloor.org>]

> I've yet to see a user who wants WC. Lets face it, WC *sucks*. This is why

Interesting.
 
> the folks who care about performance (the graphics guys) stopped using it.

I didn't know this. What do they do instead?

I understand that WC was added originally because AGP was really slow
at IO towards the CPU. You mean on PCI-E it is fast enough now
that standard cached WB works well enough?

> WC is slow, and on modern cpus leads to really bad performance. I'm really
> half tempted to just ignore WC entirely and suggest that we don't even implement
> it in the kernel. Yes it's really that bad.

At least the X server still uses it. In fact there are already some
performance regression regarding this from differing kernel behavioun
in the sysfs interfaces vs /dev/mem.

What would you recommend should the X server use instead? Always
map standard WB?  How about on older AGP systems?

-Andi