[Bug 78244] [IVB/HSW ULT]igt/gem_render_tiled_blits costs long time to execute

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=78244

Chris Wilson <chris at chris-wilson.co.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #2 from Chris Wilson <chris at chris-wilson.co.uk> ---

commit 66d5f092d46120d97a0408dcd8fea0c0e086d7a8
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date:   Thu May 8 11:56:56 2014 +0100

    igt/gem_render_tiled_blits: Speed up by using the GPU to detile

    Avoid accessing via the slow GTT to read back and compare the contents
    of each bo against expected results. It is much faster, on llc at least,
    to detile using the GPU and then copy to system memory for the compare.

    Before:

    IVB: time sudo ./gem_render_tiled_blits
    IGT-Version: 1.6-ge46ff3f (x86_64) (Linux: 3.15.0-rc3+ x86_64)
    Using 3072 1MiB buffers
    Verifying initialisation...
    Cyclic blits, forward...
    Cyclic blits, backward...
    Random blits...

    real    6m26.005s
    user    6m19.234s
    sys    0m2.414s

    PNV: time sudo ./gem_render_tiled_blits
    IGT-Version: 1.6-g8556f8a (i686) (Linux: 3.15.0-rc2+ i686)
    Using 768 1MiB buffers
    Verifying initialisation...
    Cyclic blits, forward...
    Cyclic blits, backward...
    Random blits...

    real    1m45.431s
    user    1m34.960s
    sys    0m4.624s

    Using pread:

    IVB: time sudo ./gem_render_tiled_blits
    IGT-Version: 1.6-ge46ff3f (x86_64) (Linux: 3.15.0-rc3+ x86_64)
    Using 3072 1MiB buffers
    Verifying initialisation...
    Cyclic blits, forward...
    Cyclic blits, backward...
    Random blits...

    real    0m14.717s
    user    0m3.699s
    sys    0m3.192s

    Using snoop:

    IVB: time sudo ./gem_render_tiled_blits
    IGT-Version: 1.6-ge46ff3f (x86_64) (Linux: 3.15.0-rc3+ x86_64)
    Using 3072 1MiB buffers
    Using a snoop linear buffer for comparisons
    Verifying initialisation...
    Cyclic blits, forward...
    Cyclic blits, backward...
    Random blits...

    real    0m13.774s
    user    0m3.900s
    sys    0m2.089s

    PNV: time sudo ./gem_render_tiled_blits
    IGT-Version: 1.6-g8556f8a (i686) (Linux: 3.15.0-rc2+ i686)
    Using 768 1MiB buffers
    Using a snoop linear buffer for comparisons
    Verifying initialisation...
    Cyclic blits, forward...
    Cyclic blits, backward...
    Random blits...

    real    0m20.831s
    user    0m4.384s
    sys    0m5.032s

    So roughly 10-30x faster depending on platform.

    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=78244
    Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

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