[PATCH 3/3] drm/ttm: under memory pressure minimize the size of memory pool

[Michel Dänzer]

On 13.08.2014 12:52, Jérôme Glisse wrote:
> From: Jérôme Glisse <jglisse at redhat.com>
> 
> When experiencing memory pressure we want to minimize pool size so that
> memory we just shrinked is not added back again just as the next thing.
> 
> This will divide by 2 the maximum pool size for each device each time
> the pool have to shrink. The limit is bumped again is next allocation
> happen after one second since the last shrink. The one second delay is
> obviously an arbitrary choice.
> 
> Signed-off-by: Jérôme Glisse <jglisse at redhat.com>

[...]

> diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc.c b/drivers/gpu/drm/ttm/ttm_page_alloc.c
> index 09874d6..ab41adf 100644
> --- a/drivers/gpu/drm/ttm/ttm_page_alloc.c
> +++ b/drivers/gpu/drm/ttm/ttm_page_alloc.c
> @@ -68,6 +68,8 @@
>   * @list: Pool of free uc/wc pages for fast reuse.
>   * @gfp_flags: Flags to pass for alloc_page.
>   * @npages: Number of pages in pool.
> + * @cur_max_size: Current maximum size for the pool.
> + * @shrink_timeout: Timeout for pool maximum size restriction.
>   */
>  struct ttm_page_pool {
>  	spinlock_t		lock;
> @@ -76,6 +78,8 @@ struct ttm_page_pool {
>  	gfp_t			gfp_flags;
>  	unsigned		npages;
>  	char			*name;
> +	unsigned		cur_max_size;
> +	unsigned long		last_shrink;

s/last_shrink/shrink_timeout/

Looks like maybe you posted an untested stale set of patches?


> @@ -289,6 +293,16 @@ static void ttm_pool_update_free_locked(struct ttm_page_pool *pool,
>  	pool->nfrees += freed_pages;
>  }
>  
> +static inline void ttm_pool_update_max_size(struct ttm_page_pool *pool)
> +{
> +	if (time_before(jiffies, pool->shrink_timeout))
> +		return;
> +	/* In case we reached zero bounce back to 512 pages. */
> +	pool->cur_max_size = max(pool->cur_max_size << 1, 512);

Another 'comparison of distinct pointer types lacks a cast' warning.


Both issues apply to ttm_page_alloc_dma.c as well.


-- 
Earthling Michel Dänzer            |                  http://www.amd.com
Libre software enthusiast          |                Mesa and X developer