Re: [PATCH net-next 2/4] net: page_pool: add bulk support for ptr_ring

[Ilias Apalodimas <ilias.apalodimas@linaro.org>]

Hi Lorenzo, 

On Tue, Oct 27, 2020 at 08:04:08PM +0100, Lorenzo Bianconi wrote:
> Introduce the capability to batch page_pool ptr_ring refill since it is
> usually run inside the driver NAPI tx completion loop.
> 
> Suggested-by: Jesper Dangaard Brouer <brouer@redhat.com>
> Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> ---
>  include/net/page_pool.h | 26 ++++++++++++++++++++++++++
>  net/core/page_pool.c    | 33 +++++++++++++++++++++++++++++++++
>  net/core/xdp.c          |  9 ++-------
>  3 files changed, 61 insertions(+), 7 deletions(-)
> 
> diff --git a/include/net/page_pool.h b/include/net/page_pool.h
> index 81d7773f96cd..b5b195305346 100644
> --- a/include/net/page_pool.h
> +++ b/include/net/page_pool.h
> @@ -152,6 +152,8 @@ struct page_pool *page_pool_create(const struct page_pool_params *params);
>  void page_pool_destroy(struct page_pool *pool);
>  void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *));
>  void page_pool_release_page(struct page_pool *pool, struct page *page);
> +void page_pool_put_page_bulk(struct page_pool *pool, void **data,
> +			     int count);
>  #else
>  static inline void page_pool_destroy(struct page_pool *pool)
>  {
> @@ -165,6 +167,11 @@ static inline void page_pool_release_page(struct page_pool *pool,
>  					  struct page *page)
>  {
>  }
> +
> +static inline void page_pool_put_page_bulk(struct page_pool *pool, void **data,
> +					   int count)
> +{
> +}
>  #endif
>  
>  void page_pool_put_page(struct page_pool *pool, struct page *page,
> @@ -215,4 +222,23 @@ static inline void page_pool_nid_changed(struct page_pool *pool, int new_nid)
>  	if (unlikely(pool->p.nid != new_nid))
>  		page_pool_update_nid(pool, new_nid);
>  }
> +
> +static inline void page_pool_ring_lock(struct page_pool *pool)
> +	__acquires(&pool->ring.producer_lock)
> +{
> +	if (in_serving_softirq())
> +		spin_lock(&pool->ring.producer_lock);
> +	else
> +		spin_lock_bh(&pool->ring.producer_lock);
> +}
> +
> +static inline void page_pool_ring_unlock(struct page_pool *pool)
> +	__releases(&pool->ring.producer_lock)
> +{
> +	if (in_serving_softirq())
> +		spin_unlock(&pool->ring.producer_lock);
> +	else
> +		spin_unlock_bh(&pool->ring.producer_lock);
> +}
> +
>  #endif /* _NET_PAGE_POOL_H */
> diff --git a/net/core/page_pool.c b/net/core/page_pool.c
> index ef98372facf6..84fb21f8865e 100644
> --- a/net/core/page_pool.c
> +++ b/net/core/page_pool.c
> @@ -11,6 +11,8 @@
>  #include <linux/device.h>
>  
>  #include <net/page_pool.h>
> +#include <net/xdp.h>
> +
>  #include <linux/dma-direction.h>
>  #include <linux/dma-mapping.h>
>  #include <linux/page-flags.h>
> @@ -408,6 +410,37 @@ void page_pool_put_page(struct page_pool *pool, struct page *page,
>  }
>  EXPORT_SYMBOL(page_pool_put_page);
>  
> +void page_pool_put_page_bulk(struct page_pool *pool, void **data,
> +			     int count)
> +{
> +	struct page *page_ring[XDP_BULK_QUEUE_SIZE];
> +	int i, len = 0;
> +
> +	for (i = 0; i < count; i++) {
> +		struct page *page = virt_to_head_page(data[i]);
> +
> +		if (unlikely(page_ref_count(page) != 1 ||
> +			     !pool_page_reusable(pool, page))) {
> +			page_pool_release_page(pool, page);

Mind switching this similarly to how page_pool_put_page() is using it?
unlikely -> likely and remove the !

> +			put_page(page);
> +			continue;
> +		}
> +
> +		if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
> +			page_pool_dma_sync_for_device(pool, page, -1);
> +
> +		page_ring[len++] = page;
> +	}
> +
> +	page_pool_ring_lock(pool);
> +	for (i = 0; i < len; i++) {
> +		if (__ptr_ring_produce(&pool->ring, page_ring[i]))
> +			page_pool_return_page(pool, page_ring[i]);
> +	}
> +	page_pool_ring_unlock(pool);
> +}
> +EXPORT_SYMBOL(page_pool_put_page_bulk);
> +
>  static void page_pool_empty_ring(struct page_pool *pool)
>  {
>  	struct page *page;
> diff --git a/net/core/xdp.c b/net/core/xdp.c
> index 93eabd789246..9f9a8d14df38 100644
> --- a/net/core/xdp.c
> +++ b/net/core/xdp.c
> @@ -383,16 +383,11 @@ EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);
>  void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq)
>  {
>  	struct xdp_mem_allocator *xa = bq->xa;
> -	int i;
>  
> -	if (unlikely(!xa))
> +	if (unlikely(!xa || !bq->count))
>  		return;
>  
> -	for (i = 0; i < bq->count; i++) {
> -		struct page *page = virt_to_head_page(bq->q[i]);
> -
> -		page_pool_put_full_page(xa->page_pool, page, false);
> -	}
> +	page_pool_put_page_bulk(xa->page_pool, bq->q, bq->count);
>  	bq->count = 0;
>  }
>  EXPORT_SYMBOL_GPL(xdp_flush_frame_bulk);
> -- 
> 2.26.2
> 

Cheers
/Ilias