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[PATCH v2 3/6] drm/panfrost: Add fdinfo support for memory stats

Adrián Larumbe posted 6 patches 2 years, 3 months ago
There is a newer version of this series
[PATCH v2 3/6] drm/panfrost: Add fdinfo support for memory stats
Posted by Adrián Larumbe 2 years, 3 months ago 
A new DRM GEM object function is added so that drm_show_memory_stats can
provider more accurate memory usage numbers.

Ideally, in panfrost_gem_status, the BO's purgeable flag would be checked
after locking the driver's shrinker mutex, but drm_show_memory_stats takes
over the drm file's object handle database spinlock, so there's potential
for a race condition here.

Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
---
 drivers/gpu/drm/panfrost/panfrost_drv.c |  9 +++++++--
 drivers/gpu/drm/panfrost/panfrost_gem.c | 12 ++++++++++++
 drivers/gpu/drm/panfrost/panfrost_gem.h |  1 +
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
index 3fd372301019..93d5f5538c0b 100644
--- a/drivers/gpu/drm/panfrost/panfrost_drv.c
+++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
@@ -440,11 +440,14 @@ static int panfrost_ioctl_madvise(struct drm_device *dev, void *data,
 	args->retained = drm_gem_shmem_madvise(&bo->base, args->madv);
 
 	if (args->retained) {
-		if (args->madv == PANFROST_MADV_DONTNEED)
+		if (args->madv == PANFROST_MADV_DONTNEED) {
 			list_move_tail(&bo->base.madv_list,
 				       &pfdev->shrinker_list);
-		else if (args->madv == PANFROST_MADV_WILLNEED)
+			bo->is_purgable = true;
+		} else if (args->madv == PANFROST_MADV_WILLNEED) {
 			list_del_init(&bo->base.madv_list);
+			bo->is_purgable = false;
+		}
 	}
 
 out_unlock_mappings:
@@ -559,6 +562,8 @@ static void panfrost_show_fdinfo(struct drm_printer *p, struct drm_file *file)
 	struct panfrost_device *pfdev = dev->dev_private;
 
 	panfrost_gpu_show_fdinfo(pfdev, file->driver_priv, p);
+
+	drm_show_memory_stats(p, file);
 }
 
 static const struct file_operations panfrost_drm_driver_fops = {
diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c b/drivers/gpu/drm/panfrost/panfrost_gem.c
index 3c812fbd126f..aea16b0e4dda 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gem.c
+++ b/drivers/gpu/drm/panfrost/panfrost_gem.c
@@ -195,6 +195,17 @@ static int panfrost_gem_pin(struct drm_gem_object *obj)
 	return drm_gem_shmem_pin(&bo->base);
 }
 
+static enum drm_gem_object_status panfrost_gem_status(struct drm_gem_object *obj)
+{
+	struct panfrost_gem_object *bo = to_panfrost_bo(obj);
+	enum drm_gem_object_status res = 0;
+
+	res |= (bo->is_purgable) ? DRM_GEM_OBJECT_PURGEABLE : 0;
+
+	res |= (bo->base.pages) ? DRM_GEM_OBJECT_RESIDENT : 0;
+
+	return res;
+}
 static const struct drm_gem_object_funcs panfrost_gem_funcs = {
 	.free = panfrost_gem_free_object,
 	.open = panfrost_gem_open,
@@ -206,6 +217,7 @@ static const struct drm_gem_object_funcs panfrost_gem_funcs = {
 	.vmap = drm_gem_shmem_object_vmap,
 	.vunmap = drm_gem_shmem_object_vunmap,
 	.mmap = drm_gem_shmem_object_mmap,
+	.status = panfrost_gem_status,
 	.vm_ops = &drm_gem_shmem_vm_ops,
 };
 
diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.h b/drivers/gpu/drm/panfrost/panfrost_gem.h
index ad2877eeeccd..e06f7ceb8f73 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gem.h
+++ b/drivers/gpu/drm/panfrost/panfrost_gem.h
@@ -38,6 +38,7 @@ struct panfrost_gem_object {
 
 	bool noexec		:1;
 	bool is_heap		:1;
+	bool is_purgable	:1;
 };
 
 struct panfrost_gem_mapping {
-- 
2.42.0
Re: [PATCH v2 3/6] drm/panfrost: Add fdinfo support for memory stats
Posted by Boris Brezillon 2 years, 3 months ago 
On Thu, 24 Aug 2023 02:34:46 +0100
Adrián Larumbe <adrian.larumbe@collabora.com> wrote:

> A new DRM GEM object function is added so that drm_show_memory_stats can
> provider more accurate memory usage numbers.

  s/provider/provide/

> 
> Ideally, in panfrost_gem_status, the BO's purgeable flag would be checked
> after locking the driver's shrinker mutex, but drm_show_memory_stats takes
> over the drm file's object handle database spinlock, so there's potential
> for a race condition here.

Yeah, I don't think it matters much if we report a BO non-purgeable,
and this BO becomes purgeable in the meantime. You'd have the same
problem

> 
> Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
> ---
>  drivers/gpu/drm/panfrost/panfrost_drv.c |  9 +++++++--
>  drivers/gpu/drm/panfrost/panfrost_gem.c | 12 ++++++++++++
>  drivers/gpu/drm/panfrost/panfrost_gem.h |  1 +
>  3 files changed, 20 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
> index 3fd372301019..93d5f5538c0b 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_drv.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
> @@ -440,11 +440,14 @@ static int panfrost_ioctl_madvise(struct drm_device *dev, void *data,
>  	args->retained = drm_gem_shmem_madvise(&bo->base, args->madv);
>  
>  	if (args->retained) {
> -		if (args->madv == PANFROST_MADV_DONTNEED)
> +		if (args->madv == PANFROST_MADV_DONTNEED) {
>  			list_move_tail(&bo->base.madv_list,
>  				       &pfdev->shrinker_list);
> -		else if (args->madv == PANFROST_MADV_WILLNEED)
> +			bo->is_purgable = true;
> +		} else if (args->madv == PANFROST_MADV_WILLNEED) {
>  			list_del_init(&bo->base.madv_list);
> +			bo->is_purgable = false;

Should we really flag the BO as purgeable if it's already been evicted
(args->retained == false)?

> +		}
>  	}
>  
>  out_unlock_mappings:
> @@ -559,6 +562,8 @@ static void panfrost_show_fdinfo(struct drm_printer *p, struct drm_file *file)
>  	struct panfrost_device *pfdev = dev->dev_private;
>  
>  	panfrost_gpu_show_fdinfo(pfdev, file->driver_priv, p);
> +
> +	drm_show_memory_stats(p, file);
>  }
>  
>  static const struct file_operations panfrost_drm_driver_fops = {
> diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c b/drivers/gpu/drm/panfrost/panfrost_gem.c
> index 3c812fbd126f..aea16b0e4dda 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gem.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_gem.c
> @@ -195,6 +195,17 @@ static int panfrost_gem_pin(struct drm_gem_object *obj)
>  	return drm_gem_shmem_pin(&bo->base);
>  }
>  
> +static enum drm_gem_object_status panfrost_gem_status(struct drm_gem_object *obj)
> +{
> +	struct panfrost_gem_object *bo = to_panfrost_bo(obj);
> +	enum drm_gem_object_status res = 0;
> +
> +	res |= (bo->is_purgable) ? DRM_GEM_OBJECT_PURGEABLE : 0;

Why not checking bo->base.madv here instead of adding an is_purgeable
field?

> +
> +	res |= (bo->base.pages) ? DRM_GEM_OBJECT_RESIDENT : 0;

Does it make sense to have DRM_GEM_OBJECT_PURGEABLE set when
DRM_GEM_OBJECT_RESIDENT is not?

> +
> +	return res;
> +}
>  static const struct drm_gem_object_funcs panfrost_gem_funcs = {
>  	.free = panfrost_gem_free_object,
>  	.open = panfrost_gem_open,
> @@ -206,6 +217,7 @@ static const struct drm_gem_object_funcs panfrost_gem_funcs = {
>  	.vmap = drm_gem_shmem_object_vmap,
>  	.vunmap = drm_gem_shmem_object_vunmap,
>  	.mmap = drm_gem_shmem_object_mmap,
> +	.status = panfrost_gem_status,
>  	.vm_ops = &drm_gem_shmem_vm_ops,
>  };
>  
> diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.h b/drivers/gpu/drm/panfrost/panfrost_gem.h
> index ad2877eeeccd..e06f7ceb8f73 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gem.h
> +++ b/drivers/gpu/drm/panfrost/panfrost_gem.h
> @@ -38,6 +38,7 @@ struct panfrost_gem_object {
>  
>  	bool noexec		:1;
>  	bool is_heap		:1;
> +	bool is_purgable	:1;
>  };
>  
>  struct panfrost_gem_mapping {
Re: [PATCH v2 3/6] drm/panfrost: Add fdinfo support for memory stats
Posted by Adrián Larumbe 2 years, 3 months ago 
On 30.08.2023 12:31, Boris Brezillon wrote:
>On Thu, 24 Aug 2023 02:34:46 +0100
>Adrián Larumbe <adrian.larumbe@collabora.com> wrote:
>
>> A new DRM GEM object function is added so that drm_show_memory_stats can
>> provider more accurate memory usage numbers.
>
>  s/provider/provide/
>
>> 
>> Ideally, in panfrost_gem_status, the BO's purgeable flag would be checked
>> after locking the driver's shrinker mutex, but drm_show_memory_stats takes
>> over the drm file's object handle database spinlock, so there's potential
>> for a race condition here.
>
>Yeah, I don't think it matters much if we report a BO non-purgeable,
>and this BO becomes purgeable in the meantime. You'd have the same
>problem
>
>> 
>> Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
>> ---
>>  drivers/gpu/drm/panfrost/panfrost_drv.c |  9 +++++++--
>>  drivers/gpu/drm/panfrost/panfrost_gem.c | 12 ++++++++++++
>>  drivers/gpu/drm/panfrost/panfrost_gem.h |  1 +
>>  3 files changed, 20 insertions(+), 2 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
>> index 3fd372301019..93d5f5538c0b 100644
>> --- a/drivers/gpu/drm/panfrost/panfrost_drv.c
>> +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
>> @@ -440,11 +440,14 @@ static int panfrost_ioctl_madvise(struct drm_device *dev, void *data,
>>  	args->retained = drm_gem_shmem_madvise(&bo->base, args->madv);
>>  
>>  	if (args->retained) {
>> -		if (args->madv == PANFROST_MADV_DONTNEED)
>> +		if (args->madv == PANFROST_MADV_DONTNEED) {
>>  			list_move_tail(&bo->base.madv_list,
>>  				       &pfdev->shrinker_list);
>> -		else if (args->madv == PANFROST_MADV_WILLNEED)
>> +			bo->is_purgable = true;
>> +		} else if (args->madv == PANFROST_MADV_WILLNEED) {
>>  			list_del_init(&bo->base.madv_list);
>> +			bo->is_purgable = false;
>
>Should we really flag the BO as purgeable if it's already been evicted
>(args->retained == false)?

I checked what msm is doing, and I guess it shouldn't be marked as purgeable after eviction.
I didn't catch this at first because Freedreno isn't using drm_gem_shmem_madvise, but apparently
tracking whether a BO was already purged through an additional MADV state.

>> +		}
>>  	}
>>  
>>  out_unlock_mappings:
>> @@ -559,6 +562,8 @@ static void panfrost_show_fdinfo(struct drm_printer *p, struct drm_file *file)
>>  	struct panfrost_device *pfdev = dev->dev_private;
>>  
>>  	panfrost_gpu_show_fdinfo(pfdev, file->driver_priv, p);
>> +
>> +	drm_show_memory_stats(p, file);
>>  }
>>  
>>  static const struct file_operations panfrost_drm_driver_fops = {
>> diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c b/drivers/gpu/drm/panfrost/panfrost_gem.c
>> index 3c812fbd126f..aea16b0e4dda 100644
>> --- a/drivers/gpu/drm/panfrost/panfrost_gem.c
>> +++ b/drivers/gpu/drm/panfrost/panfrost_gem.c
>> @@ -195,6 +195,17 @@ static int panfrost_gem_pin(struct drm_gem_object *obj)
>>  	return drm_gem_shmem_pin(&bo->base);
>>  }
>>  
>> +static enum drm_gem_object_status panfrost_gem_status(struct drm_gem_object *obj)
>> +{
>> +	struct panfrost_gem_object *bo = to_panfrost_bo(obj);
>> +	enum drm_gem_object_status res = 0;
>> +
>> +	res |= (bo->is_purgable) ? DRM_GEM_OBJECT_PURGEABLE : 0;
>
>Why not checking bo->base.madv here instead of adding an is_purgeable
>field?

I thought it would make the meaning more clear, but I guess there's no point in
duplicating information.

>> +
>> +	res |= (bo->base.pages) ? DRM_GEM_OBJECT_RESIDENT : 0;
>
>Does it make sense to have DRM_GEM_OBJECT_PURGEABLE set when
>DRM_GEM_OBJECT_RESIDENT is not?

Freedreno's msm_gem_status seems not to care about this because drm_show_memory_stats is already
handling this situation:

	if (s & DRM_GEM_OBJECT_RESIDENT) {
		if (obj->funcs && obj->funcs->rss)
			status.resident += obj->funcs->rss(obj);
		else
			status.resident += obj->size;
	} else {
		/* If already purged or not yet backed by pages, don't
		 * count it as purgeable:
		 */
		s &= ~DRM_GEM_OBJECT_PURGEABLE;
	}

>> +
>> +	return res;
>> +}
>>  static const struct drm_gem_object_funcs panfrost_gem_funcs = {
>>  	.free = panfrost_gem_free_object,
>>  	.open = panfrost_gem_open,
>> @@ -206,6 +217,7 @@ static const struct drm_gem_object_funcs panfrost_gem_funcs = {
>>  	.vmap = drm_gem_shmem_object_vmap,
>>  	.vunmap = drm_gem_shmem_object_vunmap,
>>  	.mmap = drm_gem_shmem_object_mmap,
>> +	.status = panfrost_gem_status,
>>  	.vm_ops = &drm_gem_shmem_vm_ops,
>>  };
>>  
>> diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.h b/drivers/gpu/drm/panfrost/panfrost_gem.h
>> index ad2877eeeccd..e06f7ceb8f73 100644
>> --- a/drivers/gpu/drm/panfrost/panfrost_gem.h
>> +++ b/drivers/gpu/drm/panfrost/panfrost_gem.h
>> @@ -38,6 +38,7 @@ struct panfrost_gem_object {
>>  
>>  	bool noexec		:1;
>>  	bool is_heap		:1;
>> +	bool is_purgable	:1;
>>  };
>>  
>>  struct panfrost_gem_mapping {

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