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Message-ID: <46D67057.9030905@yahoo.com.au>
Date: Thu, 30 Aug 2007 17:23:03 +1000
From: Nick Piggin <nickpiggin@yahoo.com.au>
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To: Peter Zijlstra <peterz@infradead.org>
CC: Dave Airlie <airlied@gmail.com>, Alan Cox <alan@lxorguk.ukuu.org.uk>,
       dri-devel <dri-devel@lists.sourceforge.net>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Linux Memory Management <linux-mm@kvack.org>
Subject: Re: uncached page allocator
References: <21d7e9970708191745h3b579f3bp72f138e089c624da@mail.gmail.com>	 <20070820094125.209e0811@the-village.bc.nu>	 <21d7e9970708202305h5128aa5cy847dafe033b00742@mail.gmail.com> <1187708165.6114.256.camel@twins>
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Peter Zijlstra wrote:
> On Tue, 2007-08-21 at 16:05 +1000, Dave Airlie wrote:
> 
> 
>>So you can see why some sort of uncached+writecombined page cache
>>would be useful, I could just allocate a bunch of pages at startup as
>>uncached+writecombined, and allocate pixmaps from them and when I
>>bind/free the pixmap I don't need the flush at all, now I'd really
>>like this to be part of the VM so that under memory pressure it can
>>just take the pages I've got in my cache back and after flushing turn
>>them back into cached pages, the other option is for the DRM to do
>>this on its own and penalise the whole system.
> 
> 
> Can't you make these pages part of the regular VM by sticking them all
> into an address_space.
> 
> And for this reclaim behaviour you'd only need to set PG_private and
> have a_ops->releasepage() dtrt.

I'd just suggest Dave just registers a shrinker to start with.

You really want to be able to batch TLB flushes as well, which
->releasepage may not be so good at (you could add more machinery
behind the releasepage to build batches and so on, but anyway, a
shrinker might be the quickest way to get something working).

-- 
SUSE Labs, Novell Inc.
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