linux-kernel - Re: [PATCH v7 5/5] drm/panfrost: Implement generic DRM object RSS reporting function

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Date:   Thu, 28 Sep 2023 13:24:46 +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 5/5] drm/panfrost: Implement generic DRM object RSS
 reporting function

Il 27/09/23 23:29, Adrián Larumbe ha scritto:
> BO's RSS is updated every time new pages are allocated on demand and mapped
> for the object at GPU page fault's IRQ handler, but only for heap buffers.
> The reason this is unnecessary for non-heap buffers is that they are mapped
> onto the GPU's VA space and backed by physical memory in their entirety at
> BO creation time.
> 
> This calculation is unnecessary for imported PRIME objects, since heap
> buffers cannot be exported by our driver, and the actual BO RSS size is the
> one reported in its attached dmabuf structure.
> 
> 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_gem.c | 15 +++++++++++++++
>   drivers/gpu/drm/panfrost/panfrost_gem.h |  5 +++++
>   drivers/gpu/drm/panfrost/panfrost_mmu.c |  1 +
>   3 files changed, 21 insertions(+)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c b/drivers/gpu/drm/panfrost/panfrost_gem.c
> index 7d8f83d20539..4365434b48db 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gem.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_gem.c
> @@ -208,6 +208,20 @@ static enum drm_gem_object_status panfrost_gem_status(struct drm_gem_object *obj
>   	return res;
>   }
>   
> +static size_t panfrost_gem_rss(struct drm_gem_object *obj)
> +{
> +	struct panfrost_gem_object *bo = to_panfrost_bo(obj);
> +
> +	if (bo->is_heap) {
> +		return bo->heap_rss_size;
> +	} else if (bo->base.pages) {
> +		WARN_ON(bo->heap_rss_size);
> +		return bo->base.base.size;
> +	} else {
> +		return 0;
> +	}

I would do, instead...

......
	if (bo->is_heap) {
		return bo->heap_rss_size;
	} else if (bo->base.pages) {
		WARN_ON(bo->heap_rss_size);
		return bo->base.base.size;
	}

	return 0;
}

Apart from that,
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>