Re: [PATCH 1/4] drm/ttm: add page order in page pool

[Christian König <christian.koenig@xxxxxxx>]

Am 22.11.2017 um 06:36 schrieb Roger He:
> to indicate page order for each element in the pool
>
> Change-Id: Ic609925ca5d2a5d4ad49d6becf505388ce3624cf
> Signed-off-by: Roger He <Hongbo.He@xxxxxxx>
> ---
>   drivers/gpu/drm/ttm/ttm_page_alloc.c | 42 ++++++++++++++++++++++++++----------
>   1 file changed, 31 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc.c b/drivers/gpu/drm/ttm/ttm_page_alloc.c
> index 72ea037..0a0c653 100644
> --- a/drivers/gpu/drm/ttm/ttm_page_alloc.c
> +++ b/drivers/gpu/drm/ttm/ttm_page_alloc.c
> @@ -81,6 +81,7 @@ struct ttm_page_pool {
>   	char			*name;
>   	unsigned long		nfrees;
>   	unsigned long		nrefills;
> +	unsigned int		order;
>   };
>   
>   /**
> @@ -412,6 +413,7 @@ ttm_pool_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
>   	struct ttm_page_pool *pool;
>   	int shrink_pages = sc->nr_to_scan;
>   	unsigned long freed = 0;
> +	unsigned int nr_free_pool;
>   
>   	if (!mutex_trylock(&lock))
>   		return SHRINK_STOP;
> @@ -421,10 +423,15 @@ ttm_pool_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
>   		unsigned nr_free = shrink_pages;
>   		if (shrink_pages == 0)
>   			break;
> +
>   		pool = &_manager->pools[(i + pool_offset)%NUM_POOLS];
>   		/* OK to use static buffer since global mutex is held. */
> -		shrink_pages = ttm_page_pool_free(pool, nr_free, true);
> -		freed += nr_free - shrink_pages;
> +		nr_free_pool = (nr_free >> pool->order);
> +		if (nr_free_pool == 0)
> +			continue;
> +
> +		shrink_pages = ttm_page_pool_free(pool, nr_free_pool, true);
> +		freed += ((nr_free_pool - shrink_pages) << pool->order);
>   	}
>   	mutex_unlock(&lock);
>   	return freed;
> @@ -436,9 +443,12 @@ ttm_pool_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
>   {
>   	unsigned i;
>   	unsigned long count = 0;
> +	struct ttm_page_pool *pool;
>   
> -	for (i = 0; i < NUM_POOLS; ++i)
> -		count += _manager->pools[i].npages;
> +	for (i = 0; i < NUM_POOLS; ++i) {
> +		pool = &_manager->pools[i];
> +		count += (pool->npages << pool->order);
> +	}
>   
>   	return count;
>   }
> @@ -932,7 +942,7 @@ static int ttm_get_pages(struct page **pages, unsigned npages, int flags,
>   }
>   
>   static void ttm_page_pool_init_locked(struct ttm_page_pool *pool, gfp_t flags,
> -		char *name)
> +		char *name, unsigned int order)
>   {
>   	spin_lock_init(&pool->lock);
>   	pool->fill_lock = false;
> @@ -940,8 +950,18 @@ static void ttm_page_pool_init_locked(struct ttm_page_pool *pool, gfp_t flags,
>   	pool->npages = pool->nfrees = 0;
>   	pool->gfp_flags = flags;
>   	pool->name = name;
> +	pool->order = order;
>   }
>   
> +/**
> + * Actually if TRANSPARENT_HUGEPAGE not enabled, we will not use
> + * wc_pool_huge and uc_pool_huge, so no matter whatever the page
> + * order are for those two pools
> + */
> +#ifndef CONFIG_TRANSPARENT_HUGEPAGE
> +#define	HPAGE_PMD_ORDER	9
> +#endif
> +

That still won't work and sorry I wasn't 100% clear in the last mail.

When CONFIG_TRANSPARENT_HUGEPAGE isn't set HPAGE_PMD_ORDER is defined as 
BUILD_BUG().

So you will still run into problems when that config option isn't set.

>   int ttm_page_alloc_init(struct ttm_mem_global *glob, unsigned max_pages)
>   {
>   	int ret;

I suggest to just handle it here like this

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
    unsigned order = HPAGE_PMD_ORDER;
#else
    unsigned order = 0;
#endif

Apart from that the patch looks good to me,
Christian.

> @@ -952,23 +972,23 @@ int ttm_page_alloc_init(struct ttm_mem_global *glob, unsigned max_pages)
>   
>   	_manager = kzalloc(sizeof(*_manager), GFP_KERNEL);
>   
> -	ttm_page_pool_init_locked(&_manager->wc_pool, GFP_HIGHUSER, "wc");
> +	ttm_page_pool_init_locked(&_manager->wc_pool, GFP_HIGHUSER, "wc", 0);
>   
> -	ttm_page_pool_init_locked(&_manager->uc_pool, GFP_HIGHUSER, "uc");
> +	ttm_page_pool_init_locked(&_manager->uc_pool, GFP_HIGHUSER, "uc", 0);
>   
>   	ttm_page_pool_init_locked(&_manager->wc_pool_dma32,
> -				  GFP_USER | GFP_DMA32, "wc dma");
> +				  GFP_USER | GFP_DMA32, "wc dma", 0);
>   
>   	ttm_page_pool_init_locked(&_manager->uc_pool_dma32,
> -				  GFP_USER | GFP_DMA32, "uc dma");
> +				  GFP_USER | GFP_DMA32, "uc dma", 0);
>   
>   	ttm_page_pool_init_locked(&_manager->wc_pool_huge,
>   				  GFP_TRANSHUGE	& ~(__GFP_MOVABLE | __GFP_COMP),
> -				  "wc huge");
> +				  "wc huge", HPAGE_PMD_ORDER);
>   
>   	ttm_page_pool_init_locked(&_manager->uc_pool_huge,
>   				  GFP_TRANSHUGE	& ~(__GFP_MOVABLE | __GFP_COMP)
> -				  , "uc huge");
> +				  , "uc huge", HPAGE_PMD_ORDER);
>   
>   	_manager->options.max_size = max_pages;
>   	_manager->options.small = SMALL_ALLOCATION;


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