Re: [PATCH 4/4] dmapool: Improve memory usage for devices which can't cross boundaries

[roel <12o3l@tiscali.nl>]

Matthew Wilcox wrote:

[...]

> @@ -142,14 +144,13 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev,
>  	if ((size % align) != 0)
>  		size = ALIGN(size, align);
>  
> -	if (allocation == 0) {
> -		if (PAGE_SIZE < size)
> -			allocation = size;
> -		else
> -			allocation = PAGE_SIZE;
> -		// FIXME: round up for less fragmentation
> -	} else if (allocation < size)
> +	allocation = max_t(size_t, size, PAGE_SIZE);
> +
> +	if (!boundary) {
> +		boundary = allocation;
> +	} else if ((boundary < size) || (boundary & (boundary - 1))) {
>  		return NULL;
> +	}

	if (!boundary)
		boundary = allocation;
	else if (boundary < size || boundary & (boundary - 1))
		return NULL;

[...]

> @@ -190,11 +192,14 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev,
>  static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
>  {
>  	unsigned int offset = 0;
> +	unsigned int next_boundary = pool->boundary;
>  
>  	do {
>  		unsigned int next = offset + pool->size;
> -		if (unlikely((next + pool->size) >= pool->allocation))
> -			next = pool->allocation;
> +		if (unlikely((next + pool->size) >= next_boundary)) {

		if (unlikely(next + pool->size >= next_boundary)) {

[...]