linux-kernel - Re: [PATCH v4 2/2] Documentation/gpu: Add fdinfo meanings of drm-*-internal memory tags

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Message-ID: <bvqjlomae7w34nawaqtrnthqvcypjui4cperriorzlv7uhngxb@4pqbagnew7in>
Date: Wed, 11 Dec 2024 17:02:54 +0000
From: Adrián Larumbe <adrian.larumbe@...labora.com>
To: Mihail Atanassov <mihail.atanassov@....com>
Cc: nd@....com, kernel@...labora.com, dri-devel@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org, Boris Brezillon <boris.brezillon@...labora.com>, 
	Steven Price <steven.price@....com>, Liviu Dudau <liviu.dudau@....com>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, 
	Simona Vetter <simona@...ll.ch>
Subject: Re: [PATCH v4 2/2] Documentation/gpu: Add fdinfo meanings of
 drm-*-internal memory tags

Hi Mihail,

On 11.12.2024 16:40, Mihail Atanassov wrote:
> Hi Adrián,
> 
> On 11/12/2024 16:34, Adrián Larumbe wrote:
> > A previous commit enabled display of driver-internal kernel BO sizes
> > through the device file's fdinfo interface.
> > 
> > Expand the description of the relevant driver-specific key:value pairs
> > with the definitions of the new drm-*-internal ones.
> > 
> > Signed-off-by: Adrián Larumbe <adrian.larumbe@...labora.com>
> > ---
> >   Documentation/gpu/panthor.rst | 14 ++++++++++++++
> >   1 file changed, 14 insertions(+)
> > 
> > diff --git a/Documentation/gpu/panthor.rst b/Documentation/gpu/panthor.rst
> > index 3f8979fa2b86..c6d8236e3665 100644
> > --- a/Documentation/gpu/panthor.rst
> > +++ b/Documentation/gpu/panthor.rst
> > @@ -26,6 +26,10 @@ the currently possible format options:
> >        drm-cycles-panthor:     94439687187
> >        drm-maxfreq-panthor:    1000000000 Hz
> >        drm-curfreq-panthor:    1000000000 Hz
> > +     drm-total-internal:     10396 KiB
> > +     drm-shared-internal:    0
> 
> You give an example of `drm-shared-internal`...
> 
> > +     drm-active-internal:    10396 KiB
> > +     drm-resident-internal:  10396 KiB
> >        drm-total-memory:       16480 KiB
> >        drm-shared-memory:      0
> >        drm-active-memory:      16200 KiB
> > @@ -44,3 +48,13 @@ driver by writing into the appropriate sysfs node::
> >   Where `N` is a bit mask where cycle and timestamp sampling are respectively
> >   enabled by the first and second bits.
> > +
> > +Possible `drm-*-internal` key names are: `total`, `active` and `resident`.
> 
> ... but don't list it as a valid key name here.

I do mention slightly further below that that key:value pair is at the time being unused,
but I've thought of a possible interpretation that could be part of another commit.

> > +These values convey the sizes of the internal driver-owned shmem BO's that
> > +aren't exposed to user-space through a DRM handle, like queue ring buffers,
> > +sync object arrays and heap chunks. Because they are all allocated and pinned
> > +at creation time, `drm-resident-internal` and `drm-total-internal` should always
> > +be equal. `drm-active-internal` shows the size of kernel BO's associated with
> > +VM's and groups currently being scheduled for execution by the GPU.
> > +`drm-shared-memory` is unused at present, but in the future it might stand for
> > +the size of the Firmware regions, since they do not belong to an open file context.
> 
> -- 
> Mihail Atanassov <mihail.atanassov@....com>

Adrian Larumbe