Re: [PATCH v4 5/6] drm: Add fdinfo memory stats

[Tvrtko Ursulin]

On 21/04/2023 12:45, Emil Velikov wrote:
> On Fri, 21 Apr 2023 at 12:23, Tvrtko Ursulin
> <tvrtko.ursulin@xxxxxxxxxxxxxxx> wrote:
>
> > On 21/04/2023 11:26, Emil Velikov wrote:
> > > On Wed, 12 Apr 2023 at 23:43, Rob Clark <robdclark@xxxxxxxxx> wrote:
> > >
> > > > +/**
> > > > + * enum drm_gem_object_status - bitmask of object state for fdinfo reporting
> > > > + * @DRM_GEM_OBJECT_RESIDENT: object is resident in memory (ie. not unpinned)
> > > > + * @DRM_GEM_OBJECT_PURGEABLE: object marked as purgeable by userspace
> > > > + *
> > > > + * Bitmask of status used for fdinfo memory stats, see &drm_gem_object_funcs.status
> > > > + * and drm_show_fdinfo().  Note that an object can DRM_GEM_OBJECT_PURGEABLE if
> > > > + * it still active or not resident, in which case drm_show_fdinfo() will not
> > >
> > > nit: s/can/can be/;s/if it still/if it is still/
> > >
> > > > + * account for it as purgeable.  So drivers do not need to check if the buffer
> > > > + * is idle and resident to return this bit.  (Ie. userspace can mark a buffer
> > > > + * as purgeable even while it is still busy on the GPU.. it does not _actually_
> > > > + * become puregeable until it becomes idle.  The status gem object func does
> > >
> > > nit: s/puregeable/purgeable/
> > >
> > >
> > > I think we want a similar note in the drm-usage-stats.rst file.
> > >
> > > With the above the whole series is:
> > > Reviewed-by: Emil Velikov <emil.l.velikov@xxxxxxxxx>
> >
> > Have you maybe noticed my slightly alternative proposal? (*) I am not a
> > fan of putting this flavour of accounting into the core with no way to
> > opt out. I think it leaves no option but to add more keys in the future
> > for any driver which will not be happy with the core accounting.
> >
> > *) https://patchwork.freedesktop.org/series/116581/
>
> Indeed I saw it. Not a fan of it, I'm afraid.

Hard to guess the reasons. :)

Anyway, at a minimum I suggest that if the no opt out version has to go 
in, it is clearly documented drm-*-memory-* is *not* about the full 
memory use of the client, but about memory belonging to user visible 
buffer objects *only*. Possibly going as far as naming the keys as 
drm-user-bo-memory-... That way there is a way to implement proper 
drm-*-memory- in the future.

Regards,

Tvrtko

> > > Fwiw: Keeping the i915 patch as part of this series would be great.
> > > Sure i915_drm_client->id becomes dead code, but it's a piece one can
> > > live with for a release or two. Then again it's not my call to make.
> >
> > Rob can take the i915 patch from my RFC too.
>
> Indeed.
>
> -Emil