Re: [PATCH 07/14] drm/ttm: page allocation use page array instead of list

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Wed, Nov 16, 2011 at 11:57:31AM -0500, j.glisse@gmail.com wrote:
> From: Jerome Glisse <jglisse@redhat.com>
> 
> Use the ttm_tt pages array for pages allocations, move the list
> unwinding into the page allocation functions.
> 
> Signed-off-by: Jerome Glisse <jglisse@redhat.com>

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

> ---
>  drivers/gpu/drm/ttm/ttm_page_alloc.c |   85 +++++++++++++++++++++-------------
>  drivers/gpu/drm/ttm/ttm_tt.c         |   36 +++------------
>  include/drm/ttm/ttm_page_alloc.h     |    8 ++--
>  3 files changed, 63 insertions(+), 66 deletions(-)
> 
> diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc.c b/drivers/gpu/drm/ttm/ttm_page_alloc.c
> index 727e93d..0f3e6d2 100644
> --- a/drivers/gpu/drm/ttm/ttm_page_alloc.c
> +++ b/drivers/gpu/drm/ttm/ttm_page_alloc.c
> @@ -619,8 +619,10 @@ static void ttm_page_pool_fill_locked(struct ttm_page_pool *pool,
>   * @return count of pages still required to fulfill the request.
>   */
>  static unsigned ttm_page_pool_get_pages(struct ttm_page_pool *pool,
> -		struct list_head *pages, int ttm_flags,
> -		enum ttm_caching_state cstate, unsigned count)
> +					struct list_head *pages,
> +					int ttm_flags,
> +					enum ttm_caching_state cstate,
> +					unsigned count)
>  {
>  	unsigned long irq_flags;
>  	struct list_head *p;
> @@ -664,13 +666,15 @@ out:
>   * On success pages list will hold count number of correctly
>   * cached pages.
>   */
> -int ttm_get_pages(struct list_head *pages, int flags,
> -		  enum ttm_caching_state cstate, unsigned count,
> +int ttm_get_pages(struct page **pages, int flags,
> +		  enum ttm_caching_state cstate, unsigned npages,
>  		  dma_addr_t *dma_address)
>  {
>  	struct ttm_page_pool *pool = ttm_get_pool(flags, cstate);
> +	struct list_head plist;
>  	struct page *p = NULL;
>  	gfp_t gfp_flags = GFP_USER;
> +	unsigned count;
>  	int r;
>  
>  	/* set zero flag for page allocation if required */
> @@ -684,7 +688,7 @@ int ttm_get_pages(struct list_head *pages, int flags,
>  		else
>  			gfp_flags |= GFP_HIGHUSER;
>  
> -		for (r = 0; r < count; ++r) {
> +		for (r = 0; r < npages; ++r) {
>  			p = alloc_page(gfp_flags);
>  			if (!p) {
>  
> @@ -693,85 +697,100 @@ int ttm_get_pages(struct list_head *pages, int flags,
>  				return -ENOMEM;
>  			}
>  
> -			list_add(&p->lru, pages);
> +			pages[r] = p;
>  		}
>  		return 0;
>  	}
>  
> -
>  	/* combine zero flag to pool flags */
>  	gfp_flags |= pool->gfp_flags;
>  
>  	/* First we take pages from the pool */
> -	count = ttm_page_pool_get_pages(pool, pages, flags, cstate, count);
> +	INIT_LIST_HEAD(&plist);
> +	npages = ttm_page_pool_get_pages(pool, &plist, flags, cstate, npages);
> +	count = 0;
> +	list_for_each_entry(p, &plist, lru) {
> +		pages[count++] = p;
> +	}
>  
>  	/* clear the pages coming from the pool if requested */
>  	if (flags & TTM_PAGE_FLAG_ZERO_ALLOC) {
> -		list_for_each_entry(p, pages, lru) {
> +		list_for_each_entry(p, &plist, lru) {
>  			clear_page(page_address(p));
>  		}
>  	}
>  
>  	/* If pool didn't have enough pages allocate new one. */
> -	if (count > 0) {
> +	if (npages > 0) {
>  		/* ttm_alloc_new_pages doesn't reference pool so we can run
>  		 * multiple requests in parallel.
>  		 **/
> -		r = ttm_alloc_new_pages(pages, gfp_flags, flags, cstate, count);
> +		INIT_LIST_HEAD(&plist);
> +		r = ttm_alloc_new_pages(&plist, gfp_flags, flags, cstate, npages);
> +		list_for_each_entry(p, &plist, lru) {
> +			pages[count++] = p;
> +		}
>  		if (r) {
>  			/* If there is any pages in the list put them back to
>  			 * the pool. */
>  			printk(KERN_ERR TTM_PFX
>  			       "Failed to allocate extra pages "
>  			       "for large request.");
> -			ttm_put_pages(pages, 0, flags, cstate, NULL);
> +			ttm_put_pages(pages, count, flags, cstate, NULL);
>  			return r;
>  		}
>  	}
>  
> -
>  	return 0;
>  }
>  
>  /* Put all pages in pages list to correct pool to wait for reuse */
> -void ttm_put_pages(struct list_head *pages, unsigned page_count, int flags,
> +void ttm_put_pages(struct page **pages, unsigned npages, int flags,
>  		   enum ttm_caching_state cstate, dma_addr_t *dma_address)
>  {
>  	unsigned long irq_flags;
>  	struct ttm_page_pool *pool = ttm_get_pool(flags, cstate);
> -	struct page *p, *tmp;
> +	unsigned i;
>  
>  	if (pool == NULL) {
>  		/* No pool for this memory type so free the pages */
> -
> -		list_for_each_entry_safe(p, tmp, pages, lru) {
> -			__free_page(p);
> +		for (i = 0; i < npages; i++) {
> +			if (pages[i]) {
> +				if (page_count(pages[i]) != 1)
> +					printk(KERN_ERR TTM_PFX
> +					       "Erroneous page count. "
> +					       "Leaking pages.\n");
> +				__free_page(pages[i]);
> +				pages[i] = NULL;
> +			}
>  		}
> -		/* Make the pages list empty */
> -		INIT_LIST_HEAD(pages);
>  		return;
>  	}
> -	if (page_count == 0) {
> -		list_for_each_entry_safe(p, tmp, pages, lru) {
> -			++page_count;
> -		}
> -	}
>  
>  	spin_lock_irqsave(&pool->lock, irq_flags);
> -	list_splice_init(pages, &pool->list);
> -	pool->npages += page_count;
> +	for (i = 0; i < npages; i++) {
> +		if (pages[i]) {
> +			if (page_count(pages[i]) != 1)
> +				printk(KERN_ERR TTM_PFX
> +				       "Erroneous page count. "
> +				       "Leaking pages.\n");
> +			list_add_tail(&pages[i]->lru, &pool->list);
> +			pages[i] = NULL;
> +			pool->npages++;
> +		}
> +	}
>  	/* Check that we don't go over the pool limit */
> -	page_count = 0;
> +	npages = 0;
>  	if (pool->npages > _manager->options.max_size) {
> -		page_count = pool->npages - _manager->options.max_size;
> +		npages = pool->npages - _manager->options.max_size;
>  		/* free at least NUM_PAGES_TO_ALLOC number of pages
>  		 * to reduce calls to set_memory_wb */
> -		if (page_count < NUM_PAGES_TO_ALLOC)
> -			page_count = NUM_PAGES_TO_ALLOC;
> +		if (npages < NUM_PAGES_TO_ALLOC)
> +			npages = NUM_PAGES_TO_ALLOC;
>  	}
>  	spin_unlock_irqrestore(&pool->lock, irq_flags);
> -	if (page_count)
> -		ttm_page_pool_free(pool, page_count);
> +	if (npages)
> +		ttm_page_pool_free(pool, npages);
>  }
>  
>  static void ttm_page_pool_init_locked(struct ttm_page_pool *pool, int flags,
> diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c
> index 54bbbad..6e079de 100644
> --- a/drivers/gpu/drm/ttm/ttm_tt.c
> +++ b/drivers/gpu/drm/ttm/ttm_tt.c
> @@ -66,22 +66,16 @@ static void ttm_tt_free_page_directory(struct ttm_tt *ttm)
>  static struct page *__ttm_tt_get_page(struct ttm_tt *ttm, int index)
>  {
>  	struct page *p;
> -	struct list_head h;
>  	struct ttm_mem_global *mem_glob = ttm->glob->mem_glob;
>  	int ret;
>  
>  	if (NULL == (p = ttm->pages[index])) {
>  
> -		INIT_LIST_HEAD(&h);
> -
> -		ret = ttm_get_pages(&h, ttm->page_flags, ttm->caching_state, 1,
> +		ret = ttm_get_pages(&p, ttm->page_flags, ttm->caching_state, 1,
>  				    &ttm->dma_address[index]);
> -
>  		if (ret != 0)
>  			return NULL;
>  
> -		p = list_first_entry(&h, struct page, lru);
> -
>  		ret = ttm_mem_global_alloc_page(mem_glob, p, false, false);
>  		if (unlikely(ret != 0))
>  			goto out_err;
> @@ -90,9 +84,7 @@ static struct page *__ttm_tt_get_page(struct ttm_tt *ttm, int index)
>  	}
>  	return p;
>  out_err:
> -	INIT_LIST_HEAD(&h);
> -	list_add(&p->lru, &h);
> -	ttm_put_pages(&h, 1, ttm->page_flags,
> +	ttm_put_pages(&p, 1, ttm->page_flags,
>  		      ttm->caching_state, &ttm->dma_address[index]);
>  	return NULL;
>  }
> @@ -243,33 +235,19 @@ EXPORT_SYMBOL(ttm_tt_set_placement_caching);
>  
>  static void ttm_tt_free_alloced_pages(struct ttm_tt *ttm)
>  {
> -	int i;
> -	unsigned count = 0;
> -	struct list_head h;
> -	struct page *cur_page;
>  	struct ttm_backend *be = ttm->be;
> -
> -	INIT_LIST_HEAD(&h);
> +	unsigned i;
>  
>  	if (be)
>  		be->func->clear(be);
>  	for (i = 0; i < ttm->num_pages; ++i) {
> -
> -		cur_page = ttm->pages[i];
> -		ttm->pages[i] = NULL;
> -		if (cur_page) {
> -			if (page_count(cur_page) != 1)
> -				printk(KERN_ERR TTM_PFX
> -				       "Erroneous page count. "
> -				       "Leaking pages.\n");
> +		if (ttm->pages[i]) {
>  			ttm_mem_global_free_page(ttm->glob->mem_glob,
> -						 cur_page);
> -			list_add(&cur_page->lru, &h);
> -			count++;
> +						 ttm->pages[i]);
> +			ttm_put_pages(&ttm->pages[i], 1, ttm->page_flags,
> +				      ttm->caching_state, &ttm->dma_address[i]);
>  		}
>  	}
> -	ttm_put_pages(&h, count, ttm->page_flags, ttm->caching_state,
> -		      ttm->dma_address);
>  	ttm->state = tt_unpopulated;
>  }
>  
> diff --git a/include/drm/ttm/ttm_page_alloc.h b/include/drm/ttm/ttm_page_alloc.h
> index 129de12..fe61c8d 100644
> --- a/include/drm/ttm/ttm_page_alloc.h
> +++ b/include/drm/ttm/ttm_page_alloc.h
> @@ -38,10 +38,10 @@
>   * @count: number of pages to allocate.
>   * @dma_address: The DMA (bus) address of pages (if TTM_PAGE_FLAG_DMA32 set).
>   */
> -int ttm_get_pages(struct list_head *pages,
> +int ttm_get_pages(struct page **pages,
>  		  int flags,
>  		  enum ttm_caching_state cstate,
> -		  unsigned count,
> +		  unsigned npages,
>  		  dma_addr_t *dma_address);
>  /**
>   * Put linked list of pages to pool.
> @@ -53,8 +53,8 @@ int ttm_get_pages(struct list_head *pages,
>   * @cstate: ttm caching state.
>   * @dma_address: The DMA (bus) address of pages (if TTM_PAGE_FLAG_DMA32 set).
>   */
> -void ttm_put_pages(struct list_head *pages,
> -		   unsigned page_count,
> +void ttm_put_pages(struct page **pages,
> +		   unsigned npages,
>  		   int flags,
>  		   enum ttm_caching_state cstate,
>  		   dma_addr_t *dma_address);
> -- 
> 1.7.7.1