On Mon, 2021-09-27 at 12:41 +0100, Matthew Auld wrote:
> This should let us do an accelerated copy directly to the shmem pages
> when temporarily moving lmem-only objects, where the i915-gem
> shrinker
> can later kick in to swap out the pages, if needed.
>
> Signed-off-by: Matthew Auld <matthew.auld@xxxxxxxxx>
> Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> index 194e5f1deda8..46d57541c0b2 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> @@ -134,11 +134,11 @@ static enum ttm_caching
> i915_ttm_select_tt_caching(const struct drm_i915_gem_object *obj)
> {
> /*
> - * Objects only allowed in system get cached cpu-mappings.
> - * Other objects get WC mapping for now. Even if in system.
> + * Objects only allowed in system get cached cpu-mappings, or
> when
> + * evicting lmem-only buffers to system for swapping. Other
> objects get
> + * WC mapping for now. Even if in system.
> */
> - if (obj->mm.region->type == INTEL_MEMORY_SYSTEM &&
> - obj->mm.n_placements <= 1)
> + if (obj->mm.n_placements <= 1)
> return ttm_cached;
>
> return ttm_write_combined;
We should be aware that with TTM, even evicted bos can be mapped by
user-space while evicted, and this will appear to user-space like the
WC-mapped object suddenly became WB-mapped. But it appears like mesa
doesn't care about this as long as the mappings are fully coherent.
Reviewed-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
