| Message ID | 20241210175939.2498-5-Yunxiang.Li@amd.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v10,1/6] drm: add drm_memory_stats_is_zero | expand |
Am 10.12.24 um 18:59 schrieb Yunxiang Li: > Tracking the state of a GEM object for shared stats is quite difficult > since the handle_count is managed behind driver's back. So instead > considers GEM object shared the moment it is exported with flink ioctl. > This makes it work the same to the dma_buf case. Add a callback for > drivers to get notified when GEM object is being shared. First of all GEM flink is pretty much deprecated, we only have it for compatibility reasons. So please don't change anything here. Then flink is not the only way to create multiple handles for a GEM object. So this here won't handle all cases. And finally we already have the .open and .close callbacks, which are called whenever a handle for a GEM object is created/destroyed. So it shouldn't be necessary in the first place. Regards, Christian. > > Signed-off-by: Yunxiang Li <Yunxiang.Li@amd.com> > > CC: dri-devel@lists.freedesktop.org > --- > drivers/gpu/drm/drm_gem.c | 3 +++ > drivers/gpu/drm/drm_prime.c | 3 +++ > include/drm/drm_gem.h | 12 +++++++++++- > 3 files changed, 17 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c > index d4bbc5d109c8b..1ead11de31f6b 100644 > --- a/drivers/gpu/drm/drm_gem.c > +++ b/drivers/gpu/drm/drm_gem.c > @@ -854,6 +854,9 @@ drm_gem_flink_ioctl(struct drm_device *dev, void *data, > goto err; > > obj->name = ret; > + > + if (obj->funcs->shared) > + obj->funcs->shared(obj); > } > > args->name = (uint64_t) obj->name; > diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c > index 0e3f8adf162f6..336d982d69807 100644 > --- a/drivers/gpu/drm/drm_prime.c > +++ b/drivers/gpu/drm/drm_prime.c > @@ -406,6 +406,9 @@ static struct dma_buf *export_and_register_object(struct drm_device *dev, > obj->dma_buf = dmabuf; > get_dma_buf(obj->dma_buf); > > + if (obj->funcs->shared) > + obj->funcs->shared(obj); > + > return dmabuf; > } > > diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h > index da11c16e212aa..8c5ffcd485752 100644 > --- a/include/drm/drm_gem.h > +++ b/include/drm/drm_gem.h > @@ -122,6 +122,16 @@ struct drm_gem_object_funcs { > */ > struct dma_buf *(*export)(struct drm_gem_object *obj, int flags); > > + /** > + * @shared: > + * > + * Callback when GEM object becomes shared, see also > + * drm_gem_object_is_shared_for_memory_stats > + * > + * This callback is optional. > + */ > + void (*shared)(struct drm_gem_object *obj); > + > /** > * @pin: > * > @@ -568,7 +578,7 @@ int drm_gem_evict(struct drm_gem_object *obj); > */ > static inline bool drm_gem_object_is_shared_for_memory_stats(struct drm_gem_object *obj) > { > - return (obj->handle_count > 1) || obj->dma_buf; > + return obj->name || obj->dma_buf; > } > > #ifdef CONFIG_LOCKDEP
[Public] > From: Koenig, Christian <Christian.Koenig@amd.com> > Sent: Wednesday, December 11, 2024 3:16 > Am 10.12.24 um 18:59 schrieb Yunxiang Li: > > Tracking the state of a GEM object for shared stats is quite difficult > > since the handle_count is managed behind driver's back. So instead > > considers GEM object shared the moment it is exported with flink ioctl. > > This makes it work the same to the dma_buf case. Add a callback for > > drivers to get notified when GEM object is being shared. > > First of all GEM flink is pretty much deprecated, we only have it for compatibility > reasons. So please don't change anything here. > > Then flink is not the only way to create multiple handles for a GEM object. So this > here won't handle all cases. > > And finally we already have the .open and .close callbacks, which are called > whenever a handle for a GEM object is created/destroyed. So it shouldn't be > necessary in the first place. For the importing VM the shared stats is automatically correct by open and close, but for the exporting VM we need to update the shared stat when the buffer gets shared, since it is already counted as private there. As far as I could find, seems like flink ioctl is the only place where the global name is assigned? The importing side have multiple places to get the global name, but the exporter always needs to first call flink to allocate the number right? So hooking into flink and dma-buf should cover the bases? I could probably make handle_count work somehow, but it looks like it's read in a lot of places without locks so I'm not sure if there will be some race conditions. > Regards, > Christian. > > > > > Signed-off-by: Yunxiang Li <Yunxiang.Li@amd.com> > > > > CC: dri-devel@lists.freedesktop.org > > --- > > drivers/gpu/drm/drm_gem.c | 3 +++ > > drivers/gpu/drm/drm_prime.c | 3 +++ > > include/drm/drm_gem.h | 12 +++++++++++- > > 3 files changed, 17 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c > > index d4bbc5d109c8b..1ead11de31f6b 100644 > > --- a/drivers/gpu/drm/drm_gem.c > > +++ b/drivers/gpu/drm/drm_gem.c > > @@ -854,6 +854,9 @@ drm_gem_flink_ioctl(struct drm_device *dev, void *data, > > goto err; > > > > obj->name = ret; > > + > > + if (obj->funcs->shared) > > + obj->funcs->shared(obj); > > } > > > > args->name = (uint64_t) obj->name; > > diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c > > index 0e3f8adf162f6..336d982d69807 100644 > > --- a/drivers/gpu/drm/drm_prime.c > > +++ b/drivers/gpu/drm/drm_prime.c > > @@ -406,6 +406,9 @@ static struct dma_buf *export_and_register_object(struct > drm_device *dev, > > obj->dma_buf = dmabuf; > > get_dma_buf(obj->dma_buf); > > > > + if (obj->funcs->shared) > > + obj->funcs->shared(obj); > > + > > return dmabuf; > > } > > > > diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h index > > da11c16e212aa..8c5ffcd485752 100644 > > --- a/include/drm/drm_gem.h > > +++ b/include/drm/drm_gem.h > > @@ -122,6 +122,16 @@ struct drm_gem_object_funcs { > > */ > > struct dma_buf *(*export)(struct drm_gem_object *obj, int flags); > > > > + /** > > + * @shared: > > + * > > + * Callback when GEM object becomes shared, see also > > + * drm_gem_object_is_shared_for_memory_stats > > + * > > + * This callback is optional. > > + */ > > + void (*shared)(struct drm_gem_object *obj); > > + > > /** > > * @pin: > > * > > @@ -568,7 +578,7 @@ int drm_gem_evict(struct drm_gem_object *obj); > > */ > > static inline bool drm_gem_object_is_shared_for_memory_stats(struct > drm_gem_object *obj) > > { > > - return (obj->handle_count > 1) || obj->dma_buf; > > + return obj->name || obj->dma_buf; > > } > > > > #ifdef CONFIG_LOCKDEP
Am 11.12.24 um 15:02 schrieb Li, Yunxiang (Teddy): > [Public] > >> From: Koenig, Christian <Christian.Koenig@amd.com> >> Sent: Wednesday, December 11, 2024 3:16 >> Am 10.12.24 um 18:59 schrieb Yunxiang Li: >>> Tracking the state of a GEM object for shared stats is quite difficult >>> since the handle_count is managed behind driver's back. So instead >>> considers GEM object shared the moment it is exported with flink ioctl. >>> This makes it work the same to the dma_buf case. Add a callback for >>> drivers to get notified when GEM object is being shared. >> First of all GEM flink is pretty much deprecated, we only have it for compatibility >> reasons. So please don't change anything here. >> >> Then flink is not the only way to create multiple handles for a GEM object. So this >> here won't handle all cases. >> >> And finally we already have the .open and .close callbacks, which are called >> whenever a handle for a GEM object is created/destroyed. So it shouldn't be >> necessary in the first place. > For the importing VM the shared stats is automatically correct by open and close, but for the exporting VM we need to update the shared stat when the buffer gets shared, since it is already counted as private there. As far as I could find, seems like flink ioctl is the only place where the global name is assigned? The importing side have multiple places to get the global name, but the exporter always needs to first call flink to allocate the number right? So hooking into flink and dma-buf should cover the bases? It's irrelevant where the global name is assigned. The problem is that there are more ways to create a new handle for a GEM object than just flink and DMA-buf. For example you can just ask a framebuffer to give you a GEM handle for the currently displayed buffer. See the call to drm_gem_handle_create() in drm_mode_getfb2_ioctl(). When you make this change here then those GEM handles are not considered shared any more even if they are and you sooner or later run into warnings on VM destruction. > I could probably make handle_count work somehow, but it looks like it's read in a lot of places without locks so I'm not sure if there will be some race conditions. The handle count is protected by the object_name_lock of the device. The drm_gem_object_is_shared_for_memory_stats() function is pretty much the only case where we read the value without holding the lock since that is used only opportunistically. What you could do is to hook into amdgpu_gem_object_open() and amdgpu_gem_object_close(), call drm_gem_object_is_shared_for_memory_stats() and go over all the VMs the BO belongs to. (See how amdgpu_vm_bo_find() and amdgpu_vm_bo_add are used). Then have an additional flag inside amdgpu_bo_va who tells you if a BO was previously considered shared or private and update the stats accordingly when that status changes. Regards, Christian. > >> Regards, >> Christian. >> >>> Signed-off-by: Yunxiang Li <Yunxiang.Li@amd.com> >>> >>> CC: dri-devel@lists.freedesktop.org >>> --- >>> drivers/gpu/drm/drm_gem.c | 3 +++ >>> drivers/gpu/drm/drm_prime.c | 3 +++ >>> include/drm/drm_gem.h | 12 +++++++++++- >>> 3 files changed, 17 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c >>> index d4bbc5d109c8b..1ead11de31f6b 100644 >>> --- a/drivers/gpu/drm/drm_gem.c >>> +++ b/drivers/gpu/drm/drm_gem.c >>> @@ -854,6 +854,9 @@ drm_gem_flink_ioctl(struct drm_device *dev, void *data, >>> goto err; >>> >>> obj->name = ret; >>> + >>> + if (obj->funcs->shared) >>> + obj->funcs->shared(obj); >>> } >>> >>> args->name = (uint64_t) obj->name; >>> diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c >>> index 0e3f8adf162f6..336d982d69807 100644 >>> --- a/drivers/gpu/drm/drm_prime.c >>> +++ b/drivers/gpu/drm/drm_prime.c >>> @@ -406,6 +406,9 @@ static struct dma_buf *export_and_register_object(struct >> drm_device *dev, >>> obj->dma_buf = dmabuf; >>> get_dma_buf(obj->dma_buf); >>> >>> + if (obj->funcs->shared) >>> + obj->funcs->shared(obj); >>> + >>> return dmabuf; >>> } >>> >>> diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h index >>> da11c16e212aa..8c5ffcd485752 100644 >>> --- a/include/drm/drm_gem.h >>> +++ b/include/drm/drm_gem.h >>> @@ -122,6 +122,16 @@ struct drm_gem_object_funcs { >>> */ >>> struct dma_buf *(*export)(struct drm_gem_object *obj, int flags); >>> >>> + /** >>> + * @shared: >>> + * >>> + * Callback when GEM object becomes shared, see also >>> + * drm_gem_object_is_shared_for_memory_stats >>> + * >>> + * This callback is optional. >>> + */ >>> + void (*shared)(struct drm_gem_object *obj); >>> + >>> /** >>> * @pin: >>> * >>> @@ -568,7 +578,7 @@ int drm_gem_evict(struct drm_gem_object *obj); >>> */ >>> static inline bool drm_gem_object_is_shared_for_memory_stats(struct >> drm_gem_object *obj) >>> { >>> - return (obj->handle_count > 1) || obj->dma_buf; >>> + return obj->name || obj->dma_buf; >>> } >>> >>> #ifdef CONFIG_LOCKDEP
[Public] > From: Koenig, Christian <Christian.Koenig@amd.com> > Sent: Wednesday, December 11, 2024 10:03 > Am 11.12.24 um 15:02 schrieb Li, Yunxiang (Teddy): > > [Public] > > > >> From: Koenig, Christian <Christian.Koenig@amd.com> > >> Sent: Wednesday, December 11, 2024 3:16 Am 10.12.24 um 18:59 schrieb > >> Yunxiang Li: > >>> Tracking the state of a GEM object for shared stats is quite > >>> difficult since the handle_count is managed behind driver's back. So > >>> instead considers GEM object shared the moment it is exported with flink ioctl. > >>> This makes it work the same to the dma_buf case. Add a callback for > >>> drivers to get notified when GEM object is being shared. > >> First of all GEM flink is pretty much deprecated, we only have it for > >> compatibility reasons. So please don't change anything here. > >> > >> Then flink is not the only way to create multiple handles for a GEM > >> object. So this here won't handle all cases. > >> > >> And finally we already have the .open and .close callbacks, which are > >> called whenever a handle for a GEM object is created/destroyed. So it > >> shouldn't be necessary in the first place. > > For the importing VM the shared stats is automatically correct by open and close, > but for the exporting VM we need to update the shared stat when the buffer gets > shared, since it is already counted as private there. As far as I could find, seems > like flink ioctl is the only place where the global name is assigned? The importing > side have multiple places to get the global name, but the exporter always needs to > first call flink to allocate the number right? So hooking into flink and dma-buf should > cover the bases? > > It's irrelevant where the global name is assigned. The problem is that there are more > ways to create a new handle for a GEM object than just flink and DMA-buf. > > For example you can just ask a framebuffer to give you a GEM handle for the > currently displayed buffer. See the call to drm_gem_handle_create() in > drm_mode_getfb2_ioctl(). > > When you make this change here then those GEM handles are not considered > shared any more even if they are and you sooner or later run into warnings on VM > destruction. > > > I could probably make handle_count work somehow, but it looks like it's read in a > lot of places without locks so I'm not sure if there will be some race conditions. > > The handle count is protected by the object_name_lock of the device. The > drm_gem_object_is_shared_for_memory_stats() function is pretty much the only > case where we read the value without holding the lock since that is used only > opportunistically. > > What you could do is to hook into amdgpu_gem_object_open() and > amdgpu_gem_object_close(), call > drm_gem_object_is_shared_for_memory_stats() and go over all the VMs the BO > belongs to. (See how amdgpu_vm_bo_find() and amdgpu_vm_bo_add are used). > > Then have an additional flag inside amdgpu_bo_va who tells you if a BO was > previously considered shared or private and update the stats accordingly when that > status changes. But the open and close functions are called outside the object_name_lock right, so do I regrab the lock in the amdgpu_* functions or I could move the callback into the lock? > Regards, > Christian. > > > > >> Regards, > >> Christian. > >> > >>> Signed-off-by: Yunxiang Li <Yunxiang.Li@amd.com> > >>> > >>> CC: dri-devel@lists.freedesktop.org > >>> --- > >>> drivers/gpu/drm/drm_gem.c | 3 +++ > >>> drivers/gpu/drm/drm_prime.c | 3 +++ > >>> include/drm/drm_gem.h | 12 +++++++++++- > >>> 3 files changed, 17 insertions(+), 1 deletion(-) > >>> > >>> diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c > >>> index d4bbc5d109c8b..1ead11de31f6b 100644 > >>> --- a/drivers/gpu/drm/drm_gem.c > >>> +++ b/drivers/gpu/drm/drm_gem.c > >>> @@ -854,6 +854,9 @@ drm_gem_flink_ioctl(struct drm_device *dev, void > *data, > >>> goto err; > >>> > >>> obj->name = ret; > >>> + > >>> + if (obj->funcs->shared) > >>> + obj->funcs->shared(obj); > >>> } > >>> > >>> args->name = (uint64_t) obj->name; diff --git > >>> a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c index > >>> 0e3f8adf162f6..336d982d69807 100644 > >>> --- a/drivers/gpu/drm/drm_prime.c > >>> +++ b/drivers/gpu/drm/drm_prime.c > >>> @@ -406,6 +406,9 @@ static struct dma_buf > >>> *export_and_register_object(struct > >> drm_device *dev, > >>> obj->dma_buf = dmabuf; > >>> get_dma_buf(obj->dma_buf); > >>> > >>> + if (obj->funcs->shared) > >>> + obj->funcs->shared(obj); > >>> + > >>> return dmabuf; > >>> } > >>> > >>> diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h index > >>> da11c16e212aa..8c5ffcd485752 100644 > >>> --- a/include/drm/drm_gem.h > >>> +++ b/include/drm/drm_gem.h > >>> @@ -122,6 +122,16 @@ struct drm_gem_object_funcs { > >>> */ > >>> struct dma_buf *(*export)(struct drm_gem_object *obj, int > >>> flags); > >>> > >>> + /** > >>> + * @shared: > >>> + * > >>> + * Callback when GEM object becomes shared, see also > >>> + * drm_gem_object_is_shared_for_memory_stats > >>> + * > >>> + * This callback is optional. > >>> + */ > >>> + void (*shared)(struct drm_gem_object *obj); > >>> + > >>> /** > >>> * @pin: > >>> * > >>> @@ -568,7 +578,7 @@ int drm_gem_evict(struct drm_gem_object *obj); > >>> */ > >>> static inline bool > >>> drm_gem_object_is_shared_for_memory_stats(struct > >> drm_gem_object *obj) > >>> { > >>> - return (obj->handle_count > 1) || obj->dma_buf; > >>> + return obj->name || obj->dma_buf; > >>> } > >>> > >>> #ifdef CONFIG_LOCKDEP
diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c index d4bbc5d109c8b..1ead11de31f6b 100644 --- a/drivers/gpu/drm/drm_gem.c +++ b/drivers/gpu/drm/drm_gem.c @@ -854,6 +854,9 @@ drm_gem_flink_ioctl(struct drm_device *dev, void *data, goto err; obj->name = ret; + + if (obj->funcs->shared) + obj->funcs->shared(obj); } args->name = (uint64_t) obj->name; diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c index 0e3f8adf162f6..336d982d69807 100644 --- a/drivers/gpu/drm/drm_prime.c +++ b/drivers/gpu/drm/drm_prime.c @@ -406,6 +406,9 @@ static struct dma_buf *export_and_register_object(struct drm_device *dev, obj->dma_buf = dmabuf; get_dma_buf(obj->dma_buf); + if (obj->funcs->shared) + obj->funcs->shared(obj); + return dmabuf; } diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h index da11c16e212aa..8c5ffcd485752 100644 --- a/include/drm/drm_gem.h +++ b/include/drm/drm_gem.h @@ -122,6 +122,16 @@ struct drm_gem_object_funcs { */ struct dma_buf *(*export)(struct drm_gem_object *obj, int flags); + /** + * @shared: + * + * Callback when GEM object becomes shared, see also + * drm_gem_object_is_shared_for_memory_stats + * + * This callback is optional. + */ + void (*shared)(struct drm_gem_object *obj); + /** * @pin: * @@ -568,7 +578,7 @@ int drm_gem_evict(struct drm_gem_object *obj); */ static inline bool drm_gem_object_is_shared_for_memory_stats(struct drm_gem_object *obj) { - return (obj->handle_count > 1) || obj->dma_buf; + return obj->name || obj->dma_buf; } #ifdef CONFIG_LOCKDEP
Tracking the state of a GEM object for shared stats is quite difficult since the handle_count is managed behind driver's back. So instead considers GEM object shared the moment it is exported with flink ioctl. This makes it work the same to the dma_buf case. Add a callback for drivers to get notified when GEM object is being shared. Signed-off-by: Yunxiang Li <Yunxiang.Li@amd.com> CC: dri-devel@lists.freedesktop.org --- drivers/gpu/drm/drm_gem.c | 3 +++ drivers/gpu/drm/drm_prime.c | 3 +++ include/drm/drm_gem.h | 12 +++++++++++- 3 files changed, 17 insertions(+), 1 deletion(-)