Messages in this thread | | | Date | Mon, 31 Mar 2008 09:08:02 -0700 | From | Arjan van de Ven <> | Subject | Re: [PATCH] x86: create array based interface to change page attribute |
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Thomas Hellström wrote:
> Let me rehprase. Not really time-critical but it is of some importance > that CPA is done quickly. > We're dealing with the tradeoff of reading from uncached device memory
uncached or write combining ?
> vs taking the pages out of > AGP, setting up a cache-coherent mapping, read and then change back. > What we'd really would like to set up is a pool of completely unmapped > (like highmem) pages. Then we could, to a large extent, avoid the CPA > calls.
changing attributes by nature means a tlb flush and a bunch of expensive cache work. That's never going to be cheap, I guess it all depends on how much work you do on the memory for it to pay off or not... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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