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    SubjectRe: TTM page pool allocator
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    On Fri, 2009-06-26 at 10:00 +1000, Dave Airlie wrote:
    > 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.
    >

    I think it's better to fix userspace to not allocate as much buffer per
    frame as it does now rather than having a pool of wb pages, i removed
    it because on my 64M box memory is getting tight, we need to compute
    the number of page we still based on memory. Also i think it's ok
    to assume that page allocation is fast enough.

    I am reworking the patch with lastes Thomas comment, will post new one
    after a bit of testing.

    Cheers,
    Jerome



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