[Intel-gfx] [RFC 3/8] drm/i915: Expose list of clients in sysfs

[Chris Wilson]

Quoting Tvrtko Ursulin (2019-12-19 18:00:14)
> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> 
> Expose a list of clients with open file handles in sysfs.
> 
> This will be a basis for a top-like utility showing per-client and per-
> engine GPU load.
> 
> Currently we only expose each client's pid and name under opaque numbered
> directories in /sys/class/drm/card0/clients/.
> 
> For instance:
> 
> /sys/class/drm/card0/clients/3/name: Xorg
> /sys/class/drm/card0/clients/3/pid: 5664
> 
> v2:
>  Chris Wilson:
>  * Enclose new members into dedicated structs.
>  * Protect against failed sysfs registration.
> 
> v3:
>  * sysfs_attr_init.
> 
> v4:
>  * Fix for internal clients.
> 
> v5:
>  * Use cyclic ida for client id. (Chris)
>  * Do not leak pid reference. (Chris)
>  * Tidy code with some locals.
> 
> v6:
>  * Use xa_alloc_cyclic to simplify locking. (Chris)
>  * No need to unregister individial sysfs files. (Chris)
>  * Rebase on top of fpriv kref.
>  * Track client closed status and reflect in sysfs.
> 
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.h   |  20 +++++
>  drivers/gpu/drm/i915/i915_gem.c   | 133 ++++++++++++++++++++++++++++--
>  drivers/gpu/drm/i915/i915_sysfs.c |   8 ++
>  3 files changed, 155 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 6f13f0c619e9..e1d8361aafd7 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -188,6 +188,7 @@ struct i915_hotplug {
>  struct drm_i915_private;
>  struct i915_mm_struct;
>  struct i915_mmu_object;
> +struct i915_drm_clients;
>  
>  struct drm_i915_file_private {
>         struct kref kref;
> @@ -226,6 +227,19 @@ struct drm_i915_file_private {
>         /** ban_score: Accumulated score of all ctx bans and fast hangs. */
>         atomic_t ban_score;
>         unsigned long hang_timestamp;
> +
> +       struct i915_drm_client {

I agree with the distinction here between drm_client and
gem_client. (This concept will be required beyond GEM.)

> +               unsigned int id;
> +               struct pid *pid;
> +               char *name;
> +               bool closed;
> +
> +               struct kobject *root;
> +               struct {
> +                       struct device_attribute pid;
> +                       struct device_attribute name;
> +               } attr;
> +       } client;
>  };
>  
>  /* Interface history:
> @@ -1280,6 +1294,12 @@ struct drm_i915_private {
>  
>         struct i915_pmu pmu;
>  
> +       struct i915_drm_clients {
> +               struct xarray xarray;
> +
> +               struct kobject *root;
> +       } clients;

You might as well pull this out into i915_drm_client.[ch]
Actually make that into a please. :)
-Chris