On Fri, Sep 29, 2023 at 11:16 AM Adrián Larumbe
<adrian.larumbe@xxxxxxxxxxxxx> wrote:
>
> Some BO's might be mapped onto physical memory chunkwise and on demand,
> like Panfrost's tiler heap. In this case, even though the
> drm_gem_shmem_object page array might already be allocated, only a very
> small fraction of the BO is currently backed by system memory, but
> drm_show_memory_stats will then proceed to add its entire virtual size to
> the file's total resident size regardless.
>
> This led to very unrealistic RSS sizes being reckoned for Panfrost, where
> said tiler heap buffer is initially allocated with a virtual size of 128
> MiB, but only a small part of it will eventually be backed by system memory
> after successive GPU page faults.
>
> Provide a new DRM object generic function that would allow drivers to
> return a more accurate RSS and purgeable sizes for their BOs.
>
> Signed-off-by: Adrián Larumbe <adrian.larumbe@xxxxxxxxxxxxx>
> Reviewed-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
> Reviewed-by: Steven Price <steven.price@xxxxxxx>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
Reviewed-by: Rob Clark <robdclark@xxxxxxxxx>
> ---
> drivers/gpu/drm/drm_file.c | 8 +++++---
> include/drm/drm_gem.h | 9 +++++++++
> 2 files changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
> index 883d83bc0e3d..9a1bd8d0d785 100644
> --- a/drivers/gpu/drm/drm_file.c
> +++ b/drivers/gpu/drm/drm_file.c
> @@ -930,6 +930,8 @@ void drm_show_memory_stats(struct drm_printer *p, struct drm_file *file)
> spin_lock(&file->table_lock);
> idr_for_each_entry (&file->object_idr, obj, id) {
> enum drm_gem_object_status s = 0;
> + size_t add_size = (obj->funcs && obj->funcs->rss) ?
> + obj->funcs->rss(obj) : obj->size;
>
> if (obj->funcs && obj->funcs->status) {
> s = obj->funcs->status(obj);
> @@ -944,7 +946,7 @@ void drm_show_memory_stats(struct drm_printer *p, struct drm_file *file)
> }
>
> if (s & DRM_GEM_OBJECT_RESIDENT) {
> - status.resident += obj->size;
> + status.resident += add_size;
> } else {
> /* If already purged or not yet backed by pages, don't
> * count it as purgeable:
> @@ -953,14 +955,14 @@ void drm_show_memory_stats(struct drm_printer *p, struct drm_file *file)
> }
>
> if (!dma_resv_test_signaled(obj->resv, dma_resv_usage_rw(true))) {
> - status.active += obj->size;
> + status.active += add_size;
>
> /* If still active, don't count as purgeable: */
> s &= ~DRM_GEM_OBJECT_PURGEABLE;
> }
>
> if (s & DRM_GEM_OBJECT_PURGEABLE)
> - status.purgeable += obj->size;
> + status.purgeable += add_size;
> }
> spin_unlock(&file->table_lock);
>
> diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
> index bc9f6aa2f3fe..16364487fde9 100644
> --- a/include/drm/drm_gem.h
> +++ b/include/drm/drm_gem.h
> @@ -208,6 +208,15 @@ struct drm_gem_object_funcs {
> */
> enum drm_gem_object_status (*status)(struct drm_gem_object *obj);
>
> + /**
> + * @rss:
> + *
> + * Return resident size of the object in physical memory.
> + *
> + * Called by drm_show_memory_stats().
> + */
> + size_t (*rss)(struct drm_gem_object *obj);
> +
> /**
> * @vm_ops:
> *
> --
> 2.42.0
>
