Re: [PATCH v2 1/2] drm: Add fdinfo memory stats

[Rob Clark]

On Tue, Apr 11, 2023 at 3:43 AM Daniel Vetter <daniel@xxxxxxxx> wrote:
>
> On Mon, Apr 10, 2023 at 02:06:06PM -0700, Rob Clark wrote:
> > From: Rob Clark <robdclark@xxxxxxxxxxxx>
> >
> > Add a helper to dump memory stats to fdinfo.  For the things the drm
> > core isn't aware of, use a callback.
> >
> > v2: Fix typos, change size units to match docs, use div_u64
> >
> > Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
> > Reviewed-by: Emil Velikov <emil.l.velikov@xxxxxxxxx>
>
> Uh can't we wire this up by default? Having this as a per-driver opt-in
> sounds like we'll get maximally fragmented drm fd_info, and since that's
> uapi I don't think that's any good at all.

That is the reason for the centralized documentation of the props (and
why for this one I added a helper, rather than continuing the current
pattern of everyone rolling their own)..

We _could_ (and I had contemplated) doing this all in core if (a) we
move madv to drm_gem_object, and (b) track
drm_gem_get_pages()/drm_gem_put_pages().  I guess neither is totally
unreasonable, pretty much all the non-ttm/non-cma GEM drivers have
some form of madvise ioctl and use
drm_gem_get_pages()/drm_gem_put_pages()..

BR,
-R

> I think it's time we have
> - drm_fd_info
> - rolled out to all drivers in their fops
> - with feature checks as appropriate
> - push the driver-specific things into a drm_driver callback
>
> And I guess start peopling giving a hard time for making things needless
> driver-specifict ... there's really no reason at all this is not
> consistent across drivers.
> -Daniel
>
> > ---
> >  Documentation/gpu/drm-usage-stats.rst | 21 +++++++
> >  drivers/gpu/drm/drm_file.c            | 79 +++++++++++++++++++++++++++
> >  include/drm/drm_file.h                | 10 ++++
> >  3 files changed, 110 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 a51ff8cee049..085b01842a87 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"
> > @@ -868,6 +869,84 @@ 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]);
> > +}
> > +
> > +/**
> > + * drm_print_memory_stats - Helper to print standard fdinfo memory stats
> > + * @file: the DRM file
> > + * @p: the printer to print output to
> > + * @status: callback to get driver tracked object status
> > + *
> > + * Helper to iterate over GEM objects with a handle allocated in the specified
> > + * file.  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.
> > + */
> > +void drm_print_memory_stats(struct drm_file *file, struct drm_printer *p,
> > +                         enum drm_gem_object_status (*status)(struct drm_gem_object *))
> > +{
> > +     struct drm_gem_object *obj;
> > +     struct {
> > +             size_t shared;
> > +             size_t private;
> > +             size_t resident;
> > +             size_t purgeable;
> > +             size_t active;
> > +     } size = {0};
> > +     int id;
> > +
> > +     spin_lock(&file->table_lock);
> > +     idr_for_each_entry (&file->object_idr, obj, id) {
> > +             enum drm_gem_object_status s = 0;
> > +
> > +             if (status)
> > +                     s = status(obj);
> > +
> > +             if (obj->handle_count > 1) {
> > +                     size.shared += obj->size;
> > +             } else {
> > +                     size.private += obj->size;
> > +             }
> > +
> > +             if (s & DRM_GEM_OBJECT_RESIDENT) {
> > +                     size.resident += obj->size;
> > +                     s &= ~DRM_GEM_OBJECT_PURGEABLE;
> > +             }
> > +
> > +             if (s & DRM_GEM_OBJECT_ACTIVE) {
> > +                     size.active += obj->size;
> > +                     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);
> > +
> > +     if (status) {
> > +             print_size(p, "drm-resident-memory", size.resident);
> > +             print_size(p, "drm-purgeable-memory", size.purgeable);
> > +             print_size(p, "drm-active-memory", size.active);
> > +     }
> > +}
> > +EXPORT_SYMBOL(drm_print_memory_stats);
> > +
> >  /**
> >   * mock_drm_getfile - Create a new struct file for the drm device
> >   * @minor: drm minor to wrap (e.g. #drm_device.primary)
> > diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h
> > index 0d1f853092ab..7bd8a1374f39 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;
> >
> > @@ -438,6 +439,15 @@ void drm_send_event_timestamp_locked(struct drm_device *dev,
> >                                    struct drm_pending_event *e,
> >                                    ktime_t timestamp);
> >
> > +enum drm_gem_object_status {
> > +     DRM_GEM_OBJECT_RESIDENT  = BIT(0),
> > +     DRM_GEM_OBJECT_PURGEABLE = BIT(1),
> > +     DRM_GEM_OBJECT_ACTIVE    = BIT(2),
> > +};
> > +
> > +void drm_print_memory_stats(struct drm_file *file, struct drm_printer *p,
> > +                         enum drm_gem_object_status (*status)(struct drm_gem_object *));
> > +
> >  struct file *mock_drm_getfile(struct drm_minor *minor, unsigned int flags);
> >
> >  #endif /* _DRM_FILE_H_ */
> > --
> > 2.39.2
> >
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch