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    SubjectRe: GEM-related desktop sluggishness due to linear-time arch_get_unmapped_area_topdown()
    On Tue, Mar 29, 2011 at 03:45:34PM -0400, Jerome Glisse wrote:
    > Short lived & small bo would definitly doesn't work well for this kind
    > of API, it would all be a function of the ioctl cost. But i am not
    > sure the drawback would be that big, intel tested with pread/pwrite
    > and gived up don't remember why. For the vbo case you describe the
    > scheme i was thinking would be : allocate bo and on buffer data call
    > upload to the allocated bo using the bind user page feature that would
    > mean zero extra copy operation. For the fire forget case of vbo,
    > likely somekind of transient buffer would be more appropriate.

    Just to clarify: Uploads to linear buffers are all done with pwrite (due
    to an api foobar, it's not so great for 2d/tiled stuff). It's amazing how
    much faster that is: Switching vbo's from mmpa to pwrite has given a few
    percent more fps in openarena in i915g! As long as the chunk you're gonna
    write fits into L1 cache, it's probably a net win.
    -Daniel
    --
    Daniel Vetter
    Mail: daniel@ffwll.ch
    Mobile: +41 (0)79 365 57 48


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