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Date: Fri, 26 Jun 2009 10:00:32 +1000
Message-ID: <21d7e9970906251700n5f5fbd07ke24022b576b1770b@mail.gmail.com>
Subject: Re: TTM page pool allocator
From: Dave Airlie <airlied@gmail.com>
To: Jerome Glisse <glisse@freedesktop.org>
Cc: thomas@shipmail.org, linux-kernel@vger.kernel.org, dri-devel@lists.sf.net
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On Thu, Jun 25, 2009 at 10:01 PM, Jerome Glisse<glisse@freedesktop.org> wrote:
> Hi,
>
> Thomas i attach a reworked page pool allocator based on Dave works,
> this one should be ok with ttm cache status tracking. It definitely
> helps on AGP system, now the bottleneck is in mesa vertex's dma
> allocation.
>

My original version kept a list of wb pages as well, this proved to be
quite a useful
optimisation on my test systems when I implemented it, without it I
was spending ~20%
of my CPU in getting free pages, granted I always used WB pages on
PCIE/IGP systems.

Another optimisation I made at the time was around the populate call,
(not sure if this
is what still happens):

Allocate a 64K local BO for DMA object.
Write into the first 5 pages from userspace - get WB pages.
Bind to GART, swap those 5 pages to WC + flush.
Then populate the rest with WC pages from the list.

Granted I think allocating WC in the first place from the pool might
work just as well since most of the DMA buffers are write only.

Dave.
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