Re: CPA patchset

Andi Kleen
2008-01-10T10:07:28Z

On Thu, Jan 10, 2008 at 11:04:43AM +0100, Ingo Molnar wrote:
>
> * Andi Kleen <ak@suse.de> wrote:
>
> > > WBINVD isnt particular fast (takes a few msecs), but why is that a
> > > problem? Drivers dont do high-frequency ioremap-ing. It's
> > > typically only done at driver/device startup and that's it.
> >
> > Actually graphics drivers can do higher frequency allocation of WC
> > memory (with PAT) support.
>
> but that's not too smart: why dont they use WB plus cflush instead?

Because they need to access it WC for performance.

> ioremap() will always be slow and we dont care about stupid uses of it.

Uninterruptible msec latencies are too slow even for slow path
initialization code imho.

-Andi