lkml.org 
[lkml]   [2008]   [Mar]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] x86: create array based interface to change page attribute
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/

\
 
 \ /
  Last update: 2008-03-31 18:13    [W:0.446 / U:0.016 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site