On Thu, Jan 28, 2010 at 7:26 PM, Luca Barbieri <l...@luca-barbieri.com> wrote:
> Currently TTM tries to preserve the previous caching even for moves
> between unrelated memory spaces.
>
> This results for instance in moves from VRAM to PCIE GART changing
> system memory to WC state needlessly.
>
> This patch changes TTM to only try to preserve caching if moving from
> system/TT to system/TT.
>
> In theory, we should also do that if moving between two device memory
> spaces that are backend by the same physical memory area.
> However, I'm not sure how to do that in the current TTM framework and
> I suspect no card/driver uses memory spaces in that way.
Thomas or Jerome (since I think placement changes were you), any
chance of ack or review?
Dave.
>
> Signed-off-by: Luca Barbieri <l...@luca-barbieri.com>
> ---
> drivers/gpu/drm/ttm/ttm_bo.c | 18 ++++++++++++++----
> 1 files changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index 2920f9a..27ee1be 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -876,6 +876,7 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo,
>
> mem->mm_node = NULL;
> for (i = 0; i < placement->num_placement; ++i) {
> + int is_tt_move;
> ret = ttm_mem_type_from_flags(placement->placement[i],
> &mem_type);
> if (ret)
> @@ -891,8 +892,12 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo,
> if (!type_ok)
> continue;
>
> - cur_flags = ttm_bo_select_caching(man, bo->mem.placement,
> - cur_flags);
> + is_tt_move = !(man->flags & TTM_MEMTYPE_FLAG_FIXED) &&
> + !(bdev->man[bo->mem.mem_type].flags &
> TTM_MEMTYPE_FLAG_FIXED);
> +
> + /* Only try to keep the current flags if we are in the same
> memory space */
> + cur_flags = ttm_bo_select_caching(man, is_tt_move ?
> bo->mem.placement : 0, cur_flags);
> +
> /*
> * Use the access and other non-mapping-related flag bits from
> * the memory placement flags to the current flags
> @@ -927,6 +932,7 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo,
> return -EINVAL;
>
> for (i = 0; i < placement->num_busy_placement; ++i) {
> + int is_tt_move;
> ret = ttm_mem_type_from_flags(placement->busy_placement[i],
> &mem_type);
> if (ret)
> @@ -941,8 +947,12 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo,
> &cur_flags))
> continue;
>
> - cur_flags = ttm_bo_select_caching(man, bo->mem.placement,
> - cur_flags);
> + is_tt_move = !(man->flags & TTM_MEMTYPE_FLAG_FIXED) &&
> + !(bdev->man[bo->mem.mem_type].flags &
> TTM_MEMTYPE_FLAG_FIXED);
> +
> + /* Only try to keep the current flags if we are in the same
> memory space */
> + cur_flags = ttm_bo_select_caching(man, is_tt_move ?
> bo->mem.placement : 0, cur_flags);
> +
> /*
> * Use the access and other non-mapping-related flag bits from
> * the memory placement flags to the current flags
> --
> 1.6.6.1.476.g01ddb
>
>
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