[Intel-gfx] [PATCH] drm/i915: Disable THP until we have a read BW W/A

[Chris Wilson]

Quoting Joonas Lahtinen (2017-11-24 11:27:50)
> We seem to be missing some W/A for 2M pages and are getting
> a hit on raw read bandwidths (even 30%) even though the write
> bandwidths improve (even 10%).
> 
> For now, disable THP, which is our only practical source of
> 2M pages until we have a W/A for the issue.
> 
> Reported-by: Valtteri Rantala <valtteri.rantala at intel.com>
> Fixes: b901bb89324a ("drm/i915/gemfs: enable THP")
> Signed-off-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: Matthew Auld <matthew.auld at intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Jani Nikula <jani.nikula at linux.intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Cc: Valtteri Rantala <valtteri.rantala at intel.com>
> Cc: Eero Tamminen <eero.t.tamminen at intel.com>

I don't have much to say, a lot of unknowns and you've already concisely
summed up everything that is known.
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris