[PATCH] drm/i915: Disable gpu relocations

[Maarten Lankhorst]

Op 2021-05-26 om 18:37 schreef Daniel Vetter:
> Media userspace was the last userspace to still use them, and they
> converted now too:
>
> https://github.com/intel/media-driver/commit/144020c37770083974bedf59902b70b8f444c799
>
> This means no reason anymore to make relocations faster than they've
> been for the first 9 years of gem. This code was added in
>
> commit 7dd4f6729f9243bd7046c6f04c107a456bda38eb
> Author: Chris Wilson <chris at chris-wilson.co.uk>
> Date:   Fri Jun 16 15:05:24 2017 +0100
>
>     drm/i915: Async GPU relocation processing
>
> Furthermore there's pretty strong indications it's buggy, since the
> code to use it by default as the only option had to be reverted:
>
> commit ad5d95e4d538737ed3fa25493777decf264a3011
> Author: Dave Airlie <airlied at redhat.com>
> Date:   Tue Sep 8 15:41:17 2020 +1000
>
>     Revert "drm/i915/gem: Async GPU relocations only"
>
> This code just disables gpu relocations, leaving the garbage
> collection for later patches and more importantly, much less confusing
> diff. Also given how much headaches this code has caused in the past,
> letting this soak for a bit seems justified.
>
> Cc: Jon Bloomfield <jon.bloomfield at intel.com>
> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Cc: "Thomas Hellström" <thomas.hellstrom at linux.intel.com>
> Cc: Matthew Auld <matthew.auld at intel.com>
> Cc: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
> Cc: Dave Airlie <airlied at redhat.com>
> Cc: Jason Ekstrand <jason at jlekstrand.net>
> ---
>  .../gpu/drm/i915/gem/i915_gem_execbuffer.c    | 43 ++++++++-----------
>  1 file changed, 18 insertions(+), 25 deletions(-)

Reviewed-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>

Note that a lot of complexity may be removed with gpu relocations gone. Some igt tests might also start to fail, as they expect relocations to complete asynchronously.

Is it kept in case we need to revive it?

~Maarten