[Bug 109119] [CI][SHARDS] igt at gem_busy@extended-semaphore-blt - fail - Failed assertion: read == active

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=109119

Martin Peres <martin.peres at free.fr> changed:

           What    |Removed                     |Added
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             Status|RESOLVED                    |CLOSED

--- Comment #3 from Martin Peres <martin.peres at free.fr> ---
(In reply to Chris Wilson from comment #2)
> Tests are defunct since
> 
> commit 6faf5916e6beb0dedb0fcbbafbaa152adeaea758
> Author: Chris Wilson <chris at chris-wilson.co.uk>
> Date:   Fri Dec 28 14:07:35 2018 +0000
> 
>     drm/i915: Remove HW semaphores for gen7 inter-engine synchronisation
>     
>     The writing is on the wall for the existence of a single execution queue
>     along each engine, and as a consequence we will not be able to track
>     dependencies along the HW queue itself, i.e. we will not be able to use
>     HW semaphores on gen7 as they use a global set of registers (and unlike
>     gen8+ we can not effectively target memory to keep per-context seqno and
>     dependencies).
>     
>     On the positive side, when we implement request reordering for gen7 we
>     also can not presume a simple execution queue and would also require
>     removing the current semaphore generation code. So this bring us another
>     step closer to request reordering for ringbuffer submission!
>     
>     The negative side is that using interrupts to drive inter-engine
>     synchronisation is much slower (4us -> 15us to do a nop on each of the 3
>     engines on ivb). This is much better than it was at the time of
> introducing
>     the HW semaphores and equally important userspace weaned itself off
>     intermixing dependent BLT/RENDER operations (the prime culprit was glyph
>     rendering in UXA). So while we regress the microbenchmarks, it should not
>     impact the user.
>     
>     References: https://bugs.freedesktop.org/show_bug.cgi?id=108888
>     Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
>     Reviewed-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>
>     Link:
> https://patchwork.freedesktop.org/patch/msgid/20181228140736.32606-2-
> chris at chris-wilson.co.uk

Thanks!

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