[Intel-gfx] [PATCH 05/38] drm/i915: Compress GPU objects in error state

[Joonas Lahtinen]

On ti, 2016-09-20 at 09:29 +0100, Chris Wilson wrote:
> @@ -175,6 +176,110 @@ static void i915_error_puts(struct drm_i915_error_state_buf *e,
>  #define err_printf(e, ...) i915_error_printf(e, __VA_ARGS__)
>  #define err_puts(e, s) i915_error_puts(e, s)
>  
> +#ifdef CONFIG_DRM_I915_COMPRESS_ERROR
> +
> +static bool compress_init(struct z_stream_s *zstream)
> +{
> +	memset(zstream, 0, sizeof(*zstream));
> +
> +	zstream->workspace =
> +		kmalloc(zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL),
> +			GFP_ATOMIC | __GFP_NOWARN);
> +	if (!zstream->workspace)
> +		return NULL;

		return false;

> +static int compress_page(struct z_stream_s *zstream,
> +			 void *src,
> +			 struct drm_i915_error_object *dst)
> +{
> +	zstream->next_in = src;
> +	zstream->avail_in = PAGE_SIZE;
> +
> +	do {
> +		if (zstream->avail_out == 0) {
> +			unsigned long page;
> +
> +			page = __get_free_page(GFP_ATOMIC | __GFP_NOWARN);
> +			if (!page)
> +				return -ENOMEM;
> +
> +			dst->pages[dst->page_count++] = (void *)page;
> +
> +			zstream->next_out = (void *)page;
> +			zstream->avail_out = PAGE_SIZE;
> +		}
> +
> +		if (zlib_deflate(zstream, Z_SYNC_FLUSH) != Z_OK)
> +			return -EIO;
> +
> +		/* Fallback to uncompressed if we increase size? */
> +		if (0 && zstream->total_out > zstream->total_in)
> +			return -E2BIG;

We could still end up decreasing in the future, so this check should
really be outside of this function at the end of compression.

> @@ -327,13 +450,23 @@ static void print_error_obj(struct drm_i915_error_state_buf *m,
>  			   lower_32_bits(obj->gtt_offset));
>  	}
>  
> -	for (page = offset = 0; page < obj->page_count; page++) {
> -		for (elt = 0; elt < PAGE_SIZE/4; elt++) {
> -			err_printf(m, "%08x :  %08x\n", offset,
> -				   obj->pages[page][elt]);
> -			offset += 4;
> +	err_compression_marker(m);
> +	for (page = 0; page < obj->page_count; page++) {
> +		int i, len;
> +
> +		len = PAGE_SIZE;
> +		if (page == obj->page_count - 1)
> +			len -= obj->unused;
> +		len = (len + 3) / 4;

Magic-ish. ascii85_length() or so.

> +	num_pages = DIV_ROUND_UP(10 * num_pages, 8); /* worstcase zlib growth */

Could be a function added to kernel zlib.

Above addressed;

Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation