Re: [PATCH v3 6/7] drm: Add fdinfo memory stats

[Daniel Vetter]

On Tue, Apr 11, 2023 at 03:56:11PM -0700, Rob Clark wrote:
> From: Rob Clark <robdclark@xxxxxxxxxxxx>
> 
> Add support to dump GEM stats to fdinfo.
> 
> v2: Fix typos, change size units to match docs, use div_u64
> v3: Do it in core
> 
> Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
> Reviewed-by: Emil Velikov <emil.l.velikov@xxxxxxxxx>
> ---
>  Documentation/gpu/drm-usage-stats.rst | 21 ++++++++
>  drivers/gpu/drm/drm_file.c            | 76 +++++++++++++++++++++++++++
>  include/drm/drm_file.h                |  1 +
>  include/drm/drm_gem.h                 | 19 +++++++
>  4 files changed, 117 insertions(+)
> 
> diff --git a/Documentation/gpu/drm-usage-stats.rst b/Documentation/gpu/drm-usage-stats.rst
> index b46327356e80..b5e7802532ed 100644
> --- a/Documentation/gpu/drm-usage-stats.rst
> +++ b/Documentation/gpu/drm-usage-stats.rst
> @@ -105,6 +105,27 @@ object belong to this client, in the respective memory region.
>  Default unit shall be bytes with optional unit specifiers of 'KiB' or 'MiB'
>  indicating kibi- or mebi-bytes.
>  
> +- drm-shared-memory: <uint> [KiB|MiB]
> +
> +The total size of buffers that are shared with another file (ie. have more
> +than a single handle).
> +
> +- drm-private-memory: <uint> [KiB|MiB]
> +
> +The total size of buffers that are not shared with another file.
> +
> +- drm-resident-memory: <uint> [KiB|MiB]
> +
> +The total size of buffers that are resident in system memory.
> +
> +- drm-purgeable-memory: <uint> [KiB|MiB]
> +
> +The total size of buffers that are purgeable.
> +
> +- drm-active-memory: <uint> [KiB|MiB]
> +
> +The total size of buffers that are active on one or more rings.
> +
>  - drm-cycles-<str> <uint>
>  
>  Engine identifier string must be the same as the one specified in the
> diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
> index 37dfaa6be560..46fdd843bb3a 100644
> --- a/drivers/gpu/drm/drm_file.c
> +++ b/drivers/gpu/drm/drm_file.c
> @@ -42,6 +42,7 @@
>  #include <drm/drm_client.h>
>  #include <drm/drm_drv.h>
>  #include <drm/drm_file.h>
> +#include <drm/drm_gem.h>
>  #include <drm/drm_print.h>
>  
>  #include "drm_crtc_internal.h"
> @@ -871,6 +872,79 @@ void drm_send_event(struct drm_device *dev, struct drm_pending_event *e)
>  }
>  EXPORT_SYMBOL(drm_send_event);
>  
> +static void print_size(struct drm_printer *p, const char *stat, size_t sz)
> +{
> +	const char *units[] = {"", " KiB", " MiB"};
> +	unsigned u;
> +
> +	for (u = 0; u < ARRAY_SIZE(units) - 1; u++) {
> +		if (sz < SZ_1K)
> +			break;
> +		sz = div_u64(sz, SZ_1K);
> +	}
> +
> +	drm_printf(p, "%s:\t%zu%s\n", stat, sz, units[u]);
> +}
> +
> +static void print_memory_stats(struct drm_printer *p, struct drm_file *file)
> +{
> +	struct drm_gem_object *obj;
> +	struct {
> +		size_t shared;
> +		size_t private;
> +		size_t resident;
> +		size_t purgeable;
> +		size_t active;
> +	} size = {0};
> +	bool has_status = false;
> +	int id;
> +
> +	spin_lock(&file->table_lock);
> +	idr_for_each_entry (&file->object_idr, obj, id) {
> +		enum drm_gem_object_status s = 0;
> +
> +		if (obj->funcs && obj->funcs->status) {
> +			s = obj->funcs->status(obj);
> +			has_status = true;
> +		}
> +
> +		if (obj->handle_count > 1) {
> +			size.shared += obj->size;
> +		} else {
> +			size.private += obj->size;
> +		}
> +
> +		if (s & DRM_GEM_OBJECT_RESIDENT) {
> +			size.resident += obj->size;
> +		} else {
> +			/* If already purged or not yet backed by pages, don't
> +			 * count it as purgeable:
> +			 */
> +			s &= ~DRM_GEM_OBJECT_PURGEABLE;
> +		}
> +
> +		if (!dma_resv_test_signaled(obj->resv, dma_resv_usage_rw(true))) {
> +			size.active += obj->size;
> +
> +			/* If still active, don't count as purgeable: */

Maybe mention this in the kerneldoc for DRM_GEM_OBJECT_PURGEABLE?

Otherwise looks tidy:

Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>

> +			s &= ~DRM_GEM_OBJECT_PURGEABLE;
> +		}
> +
> +		if (s & DRM_GEM_OBJECT_PURGEABLE)
> +			size.purgeable += obj->size;
> +	}
> +	spin_unlock(&file->table_lock);
> +
> +	print_size(p, "drm-shared-memory", size.shared);
> +	print_size(p, "drm-private-memory", size.private);
> +	print_size(p, "drm-active-memory", size.active);
> +
> +	if (has_status) {
> +		print_size(p, "drm-resident-memory", size.resident);
> +		print_size(p, "drm-purgeable-memory", size.purgeable);
> +	}
> +}
> +
>  /**
>   * drm_fop_show_fdinfo - helper for drm file fops
>   * @seq_file: output stream
> @@ -904,6 +978,8 @@ void drm_fop_show_fdinfo(struct seq_file *m, struct file *f)
>  
>  	if (dev->driver->show_fdinfo)
>  		dev->driver->show_fdinfo(&p, file);
> +
> +	print_memory_stats(&p, file);
>  }
>  EXPORT_SYMBOL(drm_fop_show_fdinfo);
>  
> diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h
> index dfa995b787e1..e5b40084538f 100644
> --- a/include/drm/drm_file.h
> +++ b/include/drm/drm_file.h
> @@ -41,6 +41,7 @@
>  struct dma_fence;
>  struct drm_file;
>  struct drm_device;
> +struct drm_printer;
>  struct device;
>  struct file;
>  
> diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
> index 189fd618ca65..213917bb6b11 100644
> --- a/include/drm/drm_gem.h
> +++ b/include/drm/drm_gem.h
> @@ -42,6 +42,14 @@
>  struct iosys_map;
>  struct drm_gem_object;
>  
> +/**
> + * enum drm_gem_object_status - bitmask of object state for fdinfo reporting
> + */
> +enum drm_gem_object_status {
> +	DRM_GEM_OBJECT_RESIDENT  = BIT(0),
> +	DRM_GEM_OBJECT_PURGEABLE = BIT(1),
> +};
> +
>  /**
>   * struct drm_gem_object_funcs - GEM object functions
>   */
> @@ -174,6 +182,17 @@ struct drm_gem_object_funcs {
>  	 */
>  	int (*evict)(struct drm_gem_object *obj);
>  
> +	/**
> +	 * @status:
> +	 *
> +	 * The optional status callback can return additional object state
> +	 * which determines which stats the object is counted against.  The
> +	 * callback is called under table_lock.  Racing against object status
> +	 * change is "harmless", and the callback can expect to not race
> +	 * against object destruction.
> +	 */
> +	enum drm_gem_object_status (*status)(struct drm_gem_object *obj);
> +
>  	/**
>  	 * @vm_ops:
>  	 *
> -- 
> 2.39.2
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch