Messages in this thread | | | Date | Thu, 10 Jan 2008 10:55:01 +0100 | From | Andi Kleen <> | Subject | Re: CPA patchset |
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On Thu, Jan 10, 2008 at 07:44:03PM +1000, Dave Airlie wrote: > > > > finally managed to get the time to review your CPA patchset, and i > > fundamentally agree with most of the detail changes done in it. But here > > are a few structural high-level observations: > > > > - firstly, there's no rationale given. So we'll change ioremap()/etc. > > from doing a cflush-range instruction instead of a WBINVD. But why? > > 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. Whether module load > > time takes 1254 msecs instead of 1250 msecs is no big deal. > > read graphics drivers, even though I think we may avoid the whole path
You mean avoid change_page_attr() ?
> if we can and end up doing some of this in the drivers > when they know more about the situation so can avoid safeties..
Please explain, but it sounds very dubious.
> but I still see this being used in AGP a fair bit at some point on > some drivers..
Well GARTs and those are widely used even without AGP busses.
-Andi
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