Re: [PATCH v5 6/6] drm/drm-file: Show finer-grained BO sizes in drm_show_memory_stats

[Boris Brezillon <boris.brezillon@collabora.com>]

On Thu, 14 Sep 2023 23:38:44 +0100
Adrián Larumbe <adrian.larumbe@collabora.com> wrote:

> The current implementation will try to pick the highest available size
> display unit as soon as the BO size exceeds that of the previous
> multiplier. That can lead to loss of precision in contexts of low memory
> usage.
> 
> The new selection criteria try to preserve precision, whilst also
> increasing the display unit selection threshold to render more accurate
> values.
> 
> Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>

Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>

> ---
>  drivers/gpu/drm/drm_file.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
> index 762965e3d503..34cfa128ffe5 100644
> --- a/drivers/gpu/drm/drm_file.c
> +++ b/drivers/gpu/drm/drm_file.c
> @@ -872,6 +872,8 @@ void drm_send_event(struct drm_device *dev, struct drm_pending_event *e)
>  }
>  EXPORT_SYMBOL(drm_send_event);
>  
> +#define UPPER_UNIT_THRESHOLD 100
> +
>  static void print_size(struct drm_printer *p, const char *stat,
>  		       const char *region, u64 sz)
>  {
> @@ -879,7 +881,8 @@ static void print_size(struct drm_printer *p, const char *stat,
>  	unsigned u;
>  
>  	for (u = 0; u < ARRAY_SIZE(units) - 1; u++) {
> -		if (sz < SZ_1K)
> +		if ((sz & (SZ_1K - 1)) &&
> +		    sz < UPPER_UNIT_THRESHOLD * SZ_1K)
>  			break;
>  		sz = div_u64(sz, SZ_1K);
>  	}