[Intel-gfx] [PATCH 06/13] drm/i915: Store a direct lookup from object handle to vma

[Joonas Lahtinen]

On ke, 2017-03-29 at 16:56 +0100, Chris Wilson wrote:
> The advent of full-ppgtt lead to an extra indirection between the object
> and its binding. That extra indirection has a noticeable impact on how
> fast we can convert from the user handles to our internal vma for
> execbuffer. In order to bypass the extra indirection, we use a
> resizable hashtable to jump from the object to the per-ctx vma.
> rhashtable was considered but we don't need the online resizing feature
> and the extra complexity proved to undermine its usefulness. Instead, we
> simply reallocate the hastable on demand in a background task and
> serialize it before iterating.
> 
> In non-full-ppgtt modes, multiple files and multiple contexts can share
> the same vma. This leads to having multiple possible handle->vma links,
> so we only use the first to establish the fast path. The majority of
> buffers are not shared and so we should still be able to realise
> speedups with multiple clients.
> 
> v2: Prettier names, more magic.
> v3: Many style tweaks, notable hiding the misuse of execobj[].rsvd2
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

Changelog checks out.

Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation