linux-kernel - Re: [PATCH v7 3/5] drm/panfrost: Add fdinfo support for memory stats

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Message-ID: <8dcc52f5-0a52-c741-1db8-1473125a21ff@collabora.com>
Date:   Thu, 28 Sep 2023 13:24:54 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Adrián Larumbe <adrian.larumbe@...labora.com>,
        maarten.lankhorst@...ux.intel.com, mripard@...nel.org,
        tzimmermann@...e.de, airlied@...il.com, daniel@...ll.ch,
        robdclark@...il.com, quic_abhinavk@...cinc.com,
        dmitry.baryshkov@...aro.org, sean@...rly.run,
        marijn.suijten@...ainline.org, robh@...nel.org,
        steven.price@....com
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, freedreno@...ts.freedesktop.org,
        healych@...zon.com, kernel@...labora.com,
        tvrtko.ursulin@...ux.intel.com, boris.brezillon@...labora.com
Subject: Re: [PATCH v7 3/5] drm/panfrost: Add fdinfo support for memory stats

Il 27/09/23 23:29, Adrián Larumbe ha scritto:
> A new DRM GEM object function is added so that drm_show_memory_stats can
> provide 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@...labora.com>
> Reviewed-by: Boris Brezillon <boris.brezillon@...labora.com>
> Reviewed-by: Steven Price <steven.price@....com>
> ---
>   drivers/gpu/drm/panfrost/panfrost_drv.c |  2 ++
>   drivers/gpu/drm/panfrost/panfrost_gem.c | 14 ++++++++++++++
>   2 files changed, 16 insertions(+)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
> index 97e5bc4a82c8..b834777b409b 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_drv.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
> @@ -568,6 +568,8 @@ 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..7d8f83d20539 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gem.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_gem.c
> @@ -195,6 +195,19 @@ 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;

The initialization of `res` is redundant...

enum drm_gem_object_status res;
res = (bo->base.madv == PANFROST_MADV_DONTNEED) ? DRM_GEM_OBJECT_PURGEABLE : 0;

P.S.: 88 columns are generally fine, so this could also fit in one line.

After that,

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>

> +
> +	res |= (bo->base.madv == PANFROST_MADV_DONTNEED) ?
> +		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 +219,7 @@ 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,
>   };
>