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Message-ID: <20081022093615.GF12453@elte.hu>
Date: Wed, 22 Oct 2008 11:36:15 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Keith Packard <keithp@...thp.com>
Cc: Jesse Barnes <jbarnes@...tuousgeek.org>,
Nick Piggin <nickpiggin@...oo.com.au>,
Dave Airlie <airlied@...ux.ie>,
Yinghai Lu <yinghai@...nel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
dri-devel@...ts.sf.net, Andrew Morton <akpm@...ux-foundation.org>,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: io resources and cached mappings (was: [git pull] drm patches
for 2.6.27-rc1)
* Keith Packard <keithp@...thp.com> wrote:
> On Mon, 2008-10-20 at 13:58 +0200, Ingo Molnar wrote:
>
> > yes but note that by caching the whole mapping on 64-bit we get
> > everything we want: trivially lockless, works from any CPU, can be
> > preempted at will, and there are no ugly INVLPG flushes anywhere.
>
> I was assuming that on 64-bit, the map would be created at driver init
> time and be left in place until the driver closed; if that's what you
> mean by 'caching', then yes, we should cache the map.
correct.
> > 32-bit we should handle as well but not design for it.
>
> As long as we get kmap_atomic-like performance, and we get to simplify
> our code, I'm up for it.
okay. So ... mind sending your io_mapping patch as a generic facility?
It looks all good to me in its present form, except that it should live
in include/linux/io.h, not in the drivers/gpu/drm/i915/io_reserve.h file
:-)
also, please send at least two patches, so that we can look at (and
possibly merge) the generic facility in isolation.
Ingo
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