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    SubjectRe: TTM page pool allocator
    Dave Airlie skrev:
    > 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.
    >

    Yes, I think in the latter case the user-space driver should take care
    to specify WC from the beginning, when the BO is allocated.

    BTW is there any DMA buffer verification taking place on WC buffers on
    Radeon?

    > Dave.
    >

    /Thomas



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