Re: [PATCH v3 1/3] drm/fdinfo: Add "evicted" memory accounting

[Tvrtko Ursulin <tursulin@ursulin.net>]

On 23/04/2026 13:33, Nicolas Frattaroli wrote:
> Currently, there's no way to know for certain how much GPU memory was
> swapped out. The difference between total and resident memory would
> include newly allocated pages, which are not resident, but also aren't
> swapped out.
> 
> Add a new drm_gem_object_status so drivers can signal when an object has
> been evicted to swap, and add a new "evicted" counter to
> drm_memory_stats.
> 
> Due to how the supported_flags bitmask is determined, the "evicted"
> count won't be printed to fdinfo if there's no swapped out pages.
> 
> Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
> ---
>   Documentation/gpu/drm-usage-stats.rst | 6 ++++++
>   drivers/gpu/drm/drm_file.c            | 8 ++++++++
>   include/drm/drm_file.h                | 2 ++
>   include/drm/drm_gem.h                 | 2 ++
>   4 files changed, 18 insertions(+)
> 
> diff --git a/Documentation/gpu/drm-usage-stats.rst b/Documentation/gpu/drm-usage-stats.rst
> index 24d3012ca7a6..11570976095e 100644
> --- a/Documentation/gpu/drm-usage-stats.rst
> +++ b/Documentation/gpu/drm-usage-stats.rst
> @@ -200,6 +200,12 @@ One practical example of this could be the presence of unsignaled fences in a
>   GEM buffer reservation object. Therefore, the active category is a subset of the
>   resident category.
>   
> +- drm-evicted-<region>: <uint> [KiB|MiB]
> +
> +The total size of buffers that have been evicted and are currently in swap
> +space. Only present if there are buffers that are currently swapped out, and the
> +driver implements reporting of this type of memory.

Please hold off merging this for a few days, I just noticed it and would 
like to set aside some time next week to think about the semantics, how 
it applies to discrete GPUs where evicted != swapped and some other 
questions.

Regards,

Tvrtko

> +
>   Implementation Details
>   ======================
>   
> diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
> index ec820686b302..5078172976c0 100644
> --- a/drivers/gpu/drm/drm_file.c
> +++ b/drivers/gpu/drm/drm_file.c
> @@ -868,6 +868,7 @@ int drm_memory_stats_is_zero(const struct drm_memory_stats *stats)
>   		stats->private == 0 &&
>   		stats->resident == 0 &&
>   		stats->purgeable == 0 &&
> +		stats->evicted == 0 &&
>   		stats->active == 0);
>   }
>   EXPORT_SYMBOL(drm_memory_stats_is_zero);
> @@ -901,6 +902,10 @@ void drm_print_memory_stats(struct drm_printer *p,
>   	if (supported_status & DRM_GEM_OBJECT_PURGEABLE)
>   		drm_fdinfo_print_size(p, prefix, "purgeable", region,
>   				      stats->purgeable);
> +
> +	if (supported_status & DRM_GEM_OBJECT_EVICTED)
> +		drm_fdinfo_print_size(p, prefix, "evicted", region,
> +				      stats->evicted);
>   }
>   EXPORT_SYMBOL(drm_print_memory_stats);
>   
> @@ -954,6 +959,9 @@ void drm_show_memory_stats(struct drm_printer *p, struct drm_file *file)
>   
>   		if (s & DRM_GEM_OBJECT_PURGEABLE)
>   			status.purgeable += add_size;
> +
> +		if (s & DRM_GEM_OBJECT_EVICTED)
> +			status.evicted += add_size;
>   	}
>   	spin_unlock(&file->table_lock);
>   
> diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h
> index 6ee70ad65e1f..213dfecac342 100644
> --- a/include/drm/drm_file.h
> +++ b/include/drm/drm_file.h
> @@ -500,6 +500,7 @@ void drm_send_event_timestamp_locked(struct drm_device *dev,
>    * @resident: Total size of GEM objects backing pages
>    * @purgeable: Total size of GEM objects that can be purged (resident and not active)
>    * @active: Total size of GEM objects active on one or more engines
> + * @evicted: Total size of GEM objects that have been evicted to swap
>    *
>    * Used by drm_print_memory_stats()
>    */
> @@ -509,6 +510,7 @@ struct drm_memory_stats {
>   	u64 resident;
>   	u64 purgeable;
>   	u64 active;
> +	u64 evicted;
>   };
>   
>   enum drm_gem_object_status;
> diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
> index 86f5846154f7..b42ea2e582cf 100644
> --- a/include/drm/drm_gem.h
> +++ b/include/drm/drm_gem.h
> @@ -53,6 +53,7 @@ struct drm_gem_object;
>    * @DRM_GEM_OBJECT_RESIDENT: object is resident in memory (ie. not unpinned)
>    * @DRM_GEM_OBJECT_PURGEABLE: object marked as purgeable by userspace
>    * @DRM_GEM_OBJECT_ACTIVE: object is currently used by an active submission
> + * @DRM_GEM_OBJECT_EVICTED: object is evicted to swap
>    *
>    * Bitmask of status used for fdinfo memory stats, see &drm_gem_object_funcs.status
>    * and drm_show_fdinfo().  Note that an object can report DRM_GEM_OBJECT_PURGEABLE
> @@ -67,6 +68,7 @@ enum drm_gem_object_status {
>   	DRM_GEM_OBJECT_RESIDENT  = BIT(0),
>   	DRM_GEM_OBJECT_PURGEABLE = BIT(1),
>   	DRM_GEM_OBJECT_ACTIVE    = BIT(2),
> +	DRM_GEM_OBJECT_EVICTED   = BIT(3),
>   };
>   
>   /**
>