[PATCH v4 net-next 0/5] xdp: introduce bulking for page_pool tx return path

[PATCH v4 net-next 0/5] xdp: introduce bulking for page_pool tx return path

[Lorenzo Bianconi]

XDP bulk APIs introduce a defer/flush mechanism to return
pages belonging to the same xdp_mem_allocator object
(identified via the mem.id field) in bulk to optimize
I-cache and D-cache since xdp_return_frame is usually run
inside the driver NAPI tx completion loop.
Convert mvneta, mvpp2 and mlx5 drivers to xdp_return_frame_bulk APIs.

Changes since v3:
- align DEV_MAP_BULK_SIZE to XDP_BULK_QUEUE_SIZE
- refactor page_pool_put_page_bulk to avoid code duplication

Changes since v2:
- move mvneta changes in a dedicated patch

Changes since v1:
- improve comments
- rework xdp_return_frame_bulk routine logic
- move count and xa fields at the beginning of xdp_frame_bulk struct
- invert logic in page_pool_put_page_bulk for loop

Lorenzo Bianconi (5):
  net: xdp: introduce bulking for xdp tx return path
  net: page_pool: add bulk support for ptr_ring
  net: mvneta: add xdp tx return bulking support
  net: mvpp2: add xdp tx return bulking support
  net: mlx5: add xdp tx return bulking support

 drivers/net/ethernet/marvell/mvneta.c         |  5 +-
 .../net/ethernet/marvell/mvpp2/mvpp2_main.c   |  5 +-
 .../net/ethernet/mellanox/mlx5/core/en/xdp.c  |  5 +-
 include/net/page_pool.h                       | 26 ++++++++
 include/net/xdp.h                             | 11 +++-
 net/core/page_pool.c                          | 66 ++++++++++++++++---
 net/core/xdp.c                                | 56 ++++++++++++++++
 7 files changed, 160 insertions(+), 14 deletions(-)

-- 
2.26.2

[PATCH v4 net-next 1/5] net: xdp: introduce bulking for xdp tx return path

[Lorenzo Bianconi]

XDP bulk APIs introduce a defer/flush mechanism to return
pages belonging to the same xdp_mem_allocator object
(identified via the mem.id field) in bulk to optimize
I-cache and D-cache since xdp_return_frame is usually run
inside the driver NAPI tx completion loop.
The bulk queue size is set to 16 to be aligned to how
XDP_REDIRECT bulking works. The bulk is flushed when
it is full or when mem.id changes.
xdp_frame_bulk is usually stored/allocated on the function
call-stack to avoid locking penalties.
Current implementation considers only page_pool memory model.

Suggested-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
 include/net/xdp.h | 11 ++++++++-
 net/core/xdp.c    | 61 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 71 insertions(+), 1 deletion(-)

diff --git a/include/net/xdp.h b/include/net/xdp.h
index 3814fb631d52..f89292ca305a 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -104,6 +104,12 @@ struct xdp_frame {
 	struct net_device *dev_rx; /* used by cpumap */
 };
 
+#define XDP_BULK_QUEUE_SIZE	16
+struct xdp_frame_bulk {
+	int count;
+	void *xa;
+	void *q[XDP_BULK_QUEUE_SIZE];
+};
 
 static inline struct skb_shared_info *
 xdp_get_shared_info_from_frame(struct xdp_frame *frame)
@@ -194,6 +200,9 @@ struct xdp_frame *xdp_convert_buff_to_frame(struct xdp_buff *xdp)
 void xdp_return_frame(struct xdp_frame *xdpf);
 void xdp_return_frame_rx_napi(struct xdp_frame *xdpf);
 void xdp_return_buff(struct xdp_buff *xdp);
+void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq);
+void xdp_return_frame_bulk(struct xdp_frame *xdpf,
+			   struct xdp_frame_bulk *bq);
 
 /* When sending xdp_frame into the network stack, then there is no
  * return point callback, which is needed to release e.g. DMA-mapping
@@ -245,6 +254,6 @@ bool xdp_attachment_flags_ok(struct xdp_attachment_info *info,
 void xdp_attachment_setup(struct xdp_attachment_info *info,
 			  struct netdev_bpf *bpf);
 
-#define DEV_MAP_BULK_SIZE 16
+#define DEV_MAP_BULK_SIZE XDP_BULK_QUEUE_SIZE
 
 #endif /* __LINUX_NET_XDP_H__ */
diff --git a/net/core/xdp.c b/net/core/xdp.c
index 48aba933a5a8..66ac275a0360 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -380,6 +380,67 @@ void xdp_return_frame_rx_napi(struct xdp_frame *xdpf)
 }
 EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);
 
+/* XDP bulk APIs introduce a defer/flush mechanism to return
+ * pages belonging to the same xdp_mem_allocator object
+ * (identified via the mem.id field) in bulk to optimize
+ * I-cache and D-cache.
+ * The bulk queue size is set to 16 to be aligned to how
+ * XDP_REDIRECT bulking works. The bulk is flushed when
+ * it is full or when mem.id changes.
+ * xdp_frame_bulk is usually stored/allocated on the function
+ * call-stack to avoid locking penalties.
+ */
+void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq)
+{
+	struct xdp_mem_allocator *xa = bq->xa;
+	int i;
+
+	if (unlikely(!xa))
+		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);
+	}
+	bq->count = 0;
+}
+EXPORT_SYMBOL_GPL(xdp_flush_frame_bulk);
+
+void xdp_return_frame_bulk(struct xdp_frame *xdpf,
+			   struct xdp_frame_bulk *bq)
+{
+	struct xdp_mem_info *mem = &xdpf->mem;
+	struct xdp_mem_allocator *xa;
+
+	if (mem->type != MEM_TYPE_PAGE_POOL) {
+		__xdp_return(xdpf->data, &xdpf->mem, false);
+		return;
+	}
+
+	rcu_read_lock();
+
+	xa = bq->xa;
+	if (unlikely(!xa)) {
+		xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
+		bq->count = 0;
+		bq->xa = xa;
+	}
+
+	if (bq->count == XDP_BULK_QUEUE_SIZE)
+		xdp_flush_frame_bulk(bq);
+
+	if (mem->id != xa->mem.id) {
+		xdp_flush_frame_bulk(bq);
+		bq->xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
+	}
+
+	bq->q[bq->count++] = xdpf->data;
+
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL_GPL(xdp_return_frame_bulk);
+
 void xdp_return_buff(struct xdp_buff *xdp)
 {
 	__xdp_return(xdp->data, &xdp->rxq->mem, true);
-- 
2.26.2

[PATCH v4 net-next 2/5] net: page_pool: add bulk support for ptr_ring

[Lorenzo Bianconi]

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    | 66 ++++++++++++++++++++++++++++++++++-------
 net/core/xdp.c          |  9 ++----
 3 files changed, 84 insertions(+), 17 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..31dac2ad4a1f 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>
@@ -362,8 +364,9 @@ static bool pool_page_reusable(struct page_pool *pool, struct page *page)
  * If the page refcnt != 1, then the page will be returned to memory
  * subsystem.
  */
-void page_pool_put_page(struct page_pool *pool, struct page *page,
-			unsigned int dma_sync_size, bool allow_direct)
+static struct page *
+__page_pool_put_page(struct page_pool *pool, struct page *page,
+		     unsigned int dma_sync_size, bool allow_direct)
 {
 	/* This allocator is optimized for the XDP mode that uses
 	 * one-frame-per-page, but have fallbacks that act like the
@@ -379,15 +382,12 @@ void page_pool_put_page(struct page_pool *pool, struct page *page,
 			page_pool_dma_sync_for_device(pool, page,
 						      dma_sync_size);
 
-		if (allow_direct && in_serving_softirq())
-			if (page_pool_recycle_in_cache(page, pool))
-				return;
+		if (allow_direct && in_serving_softirq() &&
+		    page_pool_recycle_in_cache(page, pool))
+			return NULL;
 
-		if (!page_pool_recycle_in_ring(pool, page)) {
-			/* Cache full, fallback to free pages */
-			page_pool_return_page(pool, page);
-		}
-		return;
+		/* page is candidate for bulking */
+		return page;
 	}
 	/* Fallback/non-XDP mode: API user have elevated refcnt.
 	 *
@@ -405,9 +405,55 @@ void page_pool_put_page(struct page_pool *pool, struct page *page,
 	/* Do not replace this with page_pool_return_page() */
 	page_pool_release_page(pool, page);
 	put_page(page);
+
+	return NULL;
+}
+
+void page_pool_put_page(struct page_pool *pool, struct page *page,
+			unsigned int dma_sync_size, bool allow_direct)
+{
+	page = __page_pool_put_page(pool, page, dma_sync_size, allow_direct);
+	if (page && !page_pool_recycle_in_ring(pool, page)) {
+		/* Cache full, fallback to free pages */
+		page_pool_return_page(pool, page);
+	}
 }
 EXPORT_SYMBOL(page_pool_put_page);
 
+/* Caller must not use data area after call, as this function overwrites it */
+void page_pool_put_page_bulk(struct page_pool *pool, void **data,
+			     int count)
+{
+	int i, bulk_len = 0, pa_len = 0;
+
+	for (i = 0; i < count; i++) {
+		struct page *page = virt_to_head_page(data[i]);
+
+		page = __page_pool_put_page(pool, page, -1, false);
+		/* Approved for bulk recycling in ptr_ring cache */
+		if (page)
+			data[bulk_len++] = page;
+	}
+
+	if (!bulk_len)
+		return;
+
+	/* Bulk producer into ptr_ring page_pool cache */
+	page_pool_ring_lock(pool);
+	for (i = 0; i < bulk_len; i++) {
+		if (__ptr_ring_produce(&pool->ring, data[i]))
+			data[pa_len++] = data[i];
+	}
+	page_pool_ring_unlock(pool);
+
+	/* ptr_ring cache full, free pages outside producer lock since
+	 * put_page() with refcnt == 1 can be an expensive operation
+	 */
+	for (i = 0; i < pa_len; i++)
+		page_pool_return_page(pool, data[i]);
+}
+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 66ac275a0360..ff7c801bd40c 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -393,16 +393,11 @@ 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

[PATCH v4 net-next 3/5] net: mvneta: add xdp tx return bulking support

[Lorenzo Bianconi]

Convert mvneta driver to xdp_return_frame_bulk APIs.

XDP_REDIRECT (upstream codepath): 275Kpps
XDP_REDIRECT (upstream codepath + bulking APIs): 284Kpps

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
 drivers/net/ethernet/marvell/mvneta.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index 54b0bf574c05..43ab8a73900e 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -1834,8 +1834,10 @@ static void mvneta_txq_bufs_free(struct mvneta_port *pp,
 				 struct netdev_queue *nq, bool napi)
 {
 	unsigned int bytes_compl = 0, pkts_compl = 0;
+	struct xdp_frame_bulk bq;
 	int i;
 
+	bq.xa = NULL;
 	for (i = 0; i < num; i++) {
 		struct mvneta_tx_buf *buf = &txq->buf[txq->txq_get_index];
 		struct mvneta_tx_desc *tx_desc = txq->descs +
@@ -1857,9 +1859,10 @@ static void mvneta_txq_bufs_free(struct mvneta_port *pp,
 			if (napi && buf->type == MVNETA_TYPE_XDP_TX)
 				xdp_return_frame_rx_napi(buf->xdpf);
 			else
-				xdp_return_frame(buf->xdpf);
+				xdp_return_frame_bulk(buf->xdpf, &bq);
 		}
 	}
+	xdp_flush_frame_bulk(&bq);
 
 	netdev_tx_completed_queue(nq, pkts_compl, bytes_compl);
 }
-- 
2.26.2

[PATCH v4 net-next 4/5] net: mvpp2: add xdp tx return bulking support

[Lorenzo Bianconi]

Convert mvpp2 driver to xdp_return_frame_bulk APIs.

XDP_REDIRECT (upstream codepath): 1.79Mpps
XDP_REDIRECT (upstream codepath + bulking APIs): 1.93Mpps

Tested-by: Matteo Croce <mcroce@microsoft.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
 drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
index f6616c8933ca..04f24d1d72ab 100644
--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
@@ -2440,8 +2440,10 @@ static void mvpp2_txq_bufs_free(struct mvpp2_port *port,
 				struct mvpp2_tx_queue *txq,
 				struct mvpp2_txq_pcpu *txq_pcpu, int num)
 {
+	struct xdp_frame_bulk bq;
 	int i;
 
+	bq.xa = NULL;
 	for (i = 0; i < num; i++) {
 		struct mvpp2_txq_pcpu_buf *tx_buf =
 			txq_pcpu->buffs + txq_pcpu->txq_get_index;
@@ -2454,10 +2456,11 @@ static void mvpp2_txq_bufs_free(struct mvpp2_port *port,
 			dev_kfree_skb_any(tx_buf->skb);
 		else if (tx_buf->type == MVPP2_TYPE_XDP_TX ||
 			 tx_buf->type == MVPP2_TYPE_XDP_NDO)
-			xdp_return_frame(tx_buf->xdpf);
+			xdp_return_frame_bulk(tx_buf->xdpf, &bq);
 
 		mvpp2_txq_inc_get(txq_pcpu);
 	}
+	xdp_flush_frame_bulk(&bq);
 }
 
 static inline struct mvpp2_rx_queue *mvpp2_get_rx_queue(struct mvpp2_port *port,
-- 
2.26.2

[PATCH v4 net-next 5/5] net: mlx5: add xdp tx return bulking support

[Lorenzo Bianconi]

Convert mlx5 driver to xdp_return_frame_bulk APIs.

XDP_REDIRECT (upstream codepath): 8.5Mpps
XDP_REDIRECT (upstream codepath + bulking APIs): 10.1Mpps

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
 drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
index ae90d533a350..5fdfbf390d5c 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
@@ -369,8 +369,10 @@ static void mlx5e_free_xdpsq_desc(struct mlx5e_xdpsq *sq,
 				  bool recycle)
 {
 	struct mlx5e_xdp_info_fifo *xdpi_fifo = &sq->db.xdpi_fifo;
+	struct xdp_frame_bulk bq;
 	u16 i;
 
+	bq.xa = NULL;
 	for (i = 0; i < wi->num_pkts; i++) {
 		struct mlx5e_xdp_info xdpi = mlx5e_xdpi_fifo_pop(xdpi_fifo);
 
@@ -379,7 +381,7 @@ static void mlx5e_free_xdpsq_desc(struct mlx5e_xdpsq *sq,
 			/* XDP_TX from the XSK RQ and XDP_REDIRECT */
 			dma_unmap_single(sq->pdev, xdpi.frame.dma_addr,
 					 xdpi.frame.xdpf->len, DMA_TO_DEVICE);
-			xdp_return_frame(xdpi.frame.xdpf);
+			xdp_return_frame_bulk(xdpi.frame.xdpf, &bq);
 			break;
 		case MLX5E_XDP_XMIT_MODE_PAGE:
 			/* XDP_TX from the regular RQ */
@@ -393,6 +395,7 @@ static void mlx5e_free_xdpsq_desc(struct mlx5e_xdpsq *sq,
 			WARN_ON_ONCE(true);
 		}
 	}
+	xdp_flush_frame_bulk(&bq);
 }
 
 bool mlx5e_poll_xdpsq_cq(struct mlx5e_cq *cq)
-- 
2.26.2

Re: [PATCH v4 net-next 2/5] net: page_pool: add bulk support for ptr_ring

[Jesper Dangaard Brouer]

On Fri,  6 Nov 2020 19:19:08 +0100
Lorenzo Bianconi <lorenzo@kernel.org> wrote:

> diff --git a/net/core/page_pool.c b/net/core/page_pool.c
> index ef98372facf6..31dac2ad4a1f 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>
> @@ -362,8 +364,9 @@ static bool pool_page_reusable(struct page_pool *pool, struct page *page)
>   * If the page refcnt != 1, then the page will be returned to memory
>   * subsystem.
>   */
> -void page_pool_put_page(struct page_pool *pool, struct page *page,
> -			unsigned int dma_sync_size, bool allow_direct)
> +static struct page *
> +__page_pool_put_page(struct page_pool *pool, struct page *page,
> +		     unsigned int dma_sync_size, bool allow_direct)
>  {
>  	/* This allocator is optimized for the XDP mode that uses
>  	 * one-frame-per-page, but have fallbacks that act like the
> @@ -379,15 +382,12 @@ void page_pool_put_page(struct page_pool *pool, struct page *page,
>  			page_pool_dma_sync_for_device(pool, page,
>  						      dma_sync_size);
>  
> -		if (allow_direct && in_serving_softirq())
> -			if (page_pool_recycle_in_cache(page, pool))
> -				return;
> +		if (allow_direct && in_serving_softirq() &&
> +		    page_pool_recycle_in_cache(page, pool))
> +			return NULL;
>  
> -		if (!page_pool_recycle_in_ring(pool, page)) {
> -			/* Cache full, fallback to free pages */
> -			page_pool_return_page(pool, page);
> -		}
> -		return;
> +		/* page is candidate for bulking */

I don't like this comment.  This function is also used by non-bulking
case.  Reaching this point means the page is ready or fulfill the
requirement for being recycled into the ptr_ring.

I suggest (as before):
		/* Page found as candidate for recycling */

> +		return page;
>  	}
>  	/* Fallback/non-XDP mode: API user have elevated refcnt.
>  	 *
> @@ -405,9 +405,55 @@ void page_pool_put_page(struct page_pool *pool, struct page *page,
>  	/* Do not replace this with page_pool_return_page() */
>  	page_pool_release_page(pool, page);
>  	put_page(page);
> +
> +	return NULL;
> +}
> +
> +void page_pool_put_page(struct page_pool *pool, struct page *page,
> +			unsigned int dma_sync_size, bool allow_direct)
> +{
> +	page = __page_pool_put_page(pool, page, dma_sync_size, allow_direct);
> +	if (page && !page_pool_recycle_in_ring(pool, page)) {
> +		/* Cache full, fallback to free pages */
> +		page_pool_return_page(pool, page);
> +	}
>  }
>  EXPORT_SYMBOL(page_pool_put_page);
>  
> +/* Caller must not use data area after call, as this function overwrites it */
> +void page_pool_put_page_bulk(struct page_pool *pool, void **data,
> +			     int count)
> +{
> +	int i, bulk_len = 0, pa_len = 0;
> +
> +	for (i = 0; i < count; i++) {
> +		struct page *page = virt_to_head_page(data[i]);
> +
> +		page = __page_pool_put_page(pool, page, -1, false);
> +		/* Approved for bulk recycling in ptr_ring cache */
> +		if (page)
> +			data[bulk_len++] = page;
> +	}
> +
> +	if (!bulk_len)
> +		return;
> +
> +	/* Bulk producer into ptr_ring page_pool cache */
> +	page_pool_ring_lock(pool);
> +	for (i = 0; i < bulk_len; i++) {
> +		if (__ptr_ring_produce(&pool->ring, data[i]))
> +			data[pa_len++] = data[i];
> +	}
> +	page_pool_ring_unlock(pool);
> +
> +	/* ptr_ring cache full, free pages outside producer lock since
> +	 * put_page() with refcnt == 1 can be an expensive operation
> +	 */
> +	for (i = 0; i < pa_len; i++)
> +		page_pool_return_page(pool, data[i]);
> +}
> +EXPORT_SYMBOL(page_pool_put_page_bulk);

Rest looks okay :-)
-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer

Re: [PATCH v4 net-next 2/5] net: page_pool: add bulk support for ptr_ring

[Lorenzo Bianconi]

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> On Fri,  6 Nov 2020 19:19:08 +0100
> Lorenzo Bianconi <lorenzo@kernel.org> wrote:
> 
[...]
> 
> I don't like this comment.  This function is also used by non-bulking
> case.  Reaching this point means the page is ready or fulfill the
> requirement for being recycled into the ptr_ring.
> 
> I suggest (as before):
> 		/* Page found as candidate for recycling */

ack, I will fix it in v5.

Regards,
Lorenzo

> 
> > +		return page;
> >  	}
> >  	/* Fallback/non-XDP mode: API user have elevated refcnt.
> >  	 *
> > @@ -405,9 +405,55 @@ void page_pool_put_page(struct page_pool *pool, struct page *page,
> >  	/* Do not replace this with page_pool_return_page() */
> >  	page_pool_release_page(pool, page);
> >  	put_page(page);
> > +
> > +	return NULL;
> > +}
> > +
> > +void page_pool_put_page(struct page_pool *pool, struct page *page,
> > +			unsigned int dma_sync_size, bool allow_direct)
> > +{
> > +	page = __page_pool_put_page(pool, page, dma_sync_size, allow_direct);
> > +	if (page && !page_pool_recycle_in_ring(pool, page)) {
> > +		/* Cache full, fallback to free pages */
> > +		page_pool_return_page(pool, page);
> > +	}
> >  }
> >  EXPORT_SYMBOL(page_pool_put_page);
> >  
> > +/* Caller must not use data area after call, as this function overwrites it */
> > +void page_pool_put_page_bulk(struct page_pool *pool, void **data,
> > +			     int count)
> > +{
> > +	int i, bulk_len = 0, pa_len = 0;
> > +
> > +	for (i = 0; i < count; i++) {
> > +		struct page *page = virt_to_head_page(data[i]);
> > +
> > +		page = __page_pool_put_page(pool, page, -1, false);
> > +		/* Approved for bulk recycling in ptr_ring cache */
> > +		if (page)
> > +			data[bulk_len++] = page;
> > +	}
> > +
> > +	if (!bulk_len)
> > +		return;
> > +
> > +	/* Bulk producer into ptr_ring page_pool cache */
> > +	page_pool_ring_lock(pool);
> > +	for (i = 0; i < bulk_len; i++) {
> > +		if (__ptr_ring_produce(&pool->ring, data[i]))
> > +			data[pa_len++] = data[i];
> > +	}
> > +	page_pool_ring_unlock(pool);
> > +
> > +	/* ptr_ring cache full, free pages outside producer lock since
> > +	 * put_page() with refcnt == 1 can be an expensive operation
> > +	 */
> > +	for (i = 0; i < pa_len; i++)
> > +		page_pool_return_page(pool, data[i]);
> > +}
> > +EXPORT_SYMBOL(page_pool_put_page_bulk);
> 
> Rest looks okay :-)
> -- 
> Best regards,
>   Jesper Dangaard Brouer
>   MSc.CS, Principal Kernel Engineer at Red Hat
>   LinkedIn: http://www.linkedin.com/in/brouer
> 

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Re: [PATCH v4 net-next 5/5] net: mlx5: add xdp tx return bulking support

[Jesper Dangaard Brouer]

On Fri,  6 Nov 2020 19:19:11 +0100
Lorenzo Bianconi <lorenzo@kernel.org> wrote:

> Convert mlx5 driver to xdp_return_frame_bulk APIs.
> 
> XDP_REDIRECT (upstream codepath): 8.5Mpps
> XDP_REDIRECT (upstream codepath + bulking APIs): 10.1Mpps
> 
> Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> ---
>  drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)

This patch is not 100% correct.  The bulking need to happen at another
level.  I have already fixed this up in the patches I'm currently
benchmarking with.  (Lorenzo is informed and aware)

Too many details, but all avail in[1].
 [1] https://github.com/xdp-project/xdp-project/blob/master/areas/mem/xdp_bulk_return01.org


> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
> index ae90d533a350..5fdfbf390d5c 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
> @@ -369,8 +369,10 @@ static void mlx5e_free_xdpsq_desc(struct mlx5e_xdpsq *sq,
>  				  bool recycle)
>  {
>  	struct mlx5e_xdp_info_fifo *xdpi_fifo = &sq->db.xdpi_fifo;
> +	struct xdp_frame_bulk bq;
>  	u16 i;
>  
> +	bq.xa = NULL;
>  	for (i = 0; i < wi->num_pkts; i++) {
>  		struct mlx5e_xdp_info xdpi = mlx5e_xdpi_fifo_pop(xdpi_fifo);
>  
> @@ -379,7 +381,7 @@ static void mlx5e_free_xdpsq_desc(struct mlx5e_xdpsq *sq,
>  			/* XDP_TX from the XSK RQ and XDP_REDIRECT */
>  			dma_unmap_single(sq->pdev, xdpi.frame.dma_addr,
>  					 xdpi.frame.xdpf->len, DMA_TO_DEVICE);
> -			xdp_return_frame(xdpi.frame.xdpf);
> +			xdp_return_frame_bulk(xdpi.frame.xdpf, &bq);
>  			break;
>  		case MLX5E_XDP_XMIT_MODE_PAGE:
>  			/* XDP_TX from the regular RQ */
> @@ -393,6 +395,7 @@ static void mlx5e_free_xdpsq_desc(struct mlx5e_xdpsq *sq,
>  			WARN_ON_ONCE(true);
>  		}
>  	}
> +	xdp_flush_frame_bulk(&bq);
>  }
>  
>  bool mlx5e_poll_xdpsq_cq(struct mlx5e_cq *cq)



-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer

Re: [PATCH v4 net-next 1/5] net: xdp: introduce bulking for xdp tx return path

[Jesper Dangaard Brouer]

On Fri,  6 Nov 2020 19:19:07 +0100
Lorenzo Bianconi <lorenzo@kernel.org> wrote:

> XDP bulk APIs introduce a defer/flush mechanism to return
> pages belonging to the same xdp_mem_allocator object
> (identified via the mem.id field) in bulk to optimize
> I-cache and D-cache since xdp_return_frame is usually run
> inside the driver NAPI tx completion loop.
> The bulk queue size is set to 16 to be aligned to how
> XDP_REDIRECT bulking works. The bulk is flushed when
> it is full or when mem.id changes.
> xdp_frame_bulk is usually stored/allocated on the function
> call-stack to avoid locking penalties.
> Current implementation considers only page_pool memory model.
> 
> Suggested-by: Jesper Dangaard Brouer <brouer@redhat.com>
> Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> ---
>  include/net/xdp.h | 11 ++++++++-
>  net/core/xdp.c    | 61 +++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 71 insertions(+), 1 deletion(-)

I have a number of optimization improvements to this patch.  Mostly
related to simple likely/unlikely compiler annotations, that give
better code layout for I-cache benefit.  Details in[1]. (Lorenzo is informed)

[1] https://github.com/xdp-project/xdp-project/blob/master/areas/mem/xdp_bulk_return01.org
-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer

Re: [PATCH v4 net-next 2/5] net: page_pool: add bulk support for ptr_ring

[Jesper Dangaard Brouer]

On Fri,  6 Nov 2020 19:19:08 +0100
Lorenzo Bianconi <lorenzo@kernel.org> 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    | 66 ++++++++++++++++++++++++++++++++++-------
>  net/core/xdp.c          |  9 ++----
>  3 files changed, 84 insertions(+), 17 deletions(-)

My own suggestion to create __page_pool_put_page() for code sharing,
cause a performance regression, because compiler chooses not to inline
the function.  This cause unnecessary code for in_serving_softirq() and
function call overhead.

I'm currently testing with __always_inline and likely/unlikely
annotation to get compiler to layout code better for I-cache.  This
shows improvements in my benchmarks. Details in[1].

[1] https://github.com/xdp-project/xdp-project/blob/master/areas/mem/xdp_bulk_return01.org

> diff --git a/net/core/page_pool.c b/net/core/page_pool.c
> index ef98372facf6..31dac2ad4a1f 100644
> --- a/net/core/page_pool.c
> +++ b/net/core/page_pool.c
[...]
> @@ -362,8 +364,9 @@ static bool pool_page_reusable(struct page_pool *pool, struct page *page)
>   * If the page refcnt != 1, then the page will be returned to memory
>   * subsystem.
>   */
> -void page_pool_put_page(struct page_pool *pool, struct page *page,
> -			unsigned int dma_sync_size, bool allow_direct)
> +static struct page *
> +__page_pool_put_page(struct page_pool *pool, struct page *page,
> +		     unsigned int dma_sync_size, bool allow_direct)
>  {
>  	/* This allocator is optimized for the XDP mode that uses
>  	 * one-frame-per-page, but have fallbacks that act like the
> @@ -379,15 +382,12 @@ void page_pool_put_page(struct page_pool *pool, struct page *page,
>  			page_pool_dma_sync_for_device(pool, page,
>  						      dma_sync_size);
>  
> -		if (allow_direct && in_serving_softirq())
> -			if (page_pool_recycle_in_cache(page, pool))
> -				return;
> +		if (allow_direct && in_serving_softirq() &&
> +		    page_pool_recycle_in_cache(page, pool))
> +			return NULL;
>  
> -		if (!page_pool_recycle_in_ring(pool, page)) {
> -			/* Cache full, fallback to free pages */
> -			page_pool_return_page(pool, page);
> -		}
> -		return;
> +		/* page is candidate for bulking */
> +		return page;
>  	}
>  	/* Fallback/non-XDP mode: API user have elevated refcnt.
>  	 *
> @@ -405,9 +405,55 @@ void page_pool_put_page(struct page_pool *pool, struct page *page,
>  	/* Do not replace this with page_pool_return_page() */
>  	page_pool_release_page(pool, page);
>  	put_page(page);
> +
> +	return NULL;
> +}
> +
> +void page_pool_put_page(struct page_pool *pool, struct page *page,
> +			unsigned int dma_sync_size, bool allow_direct)
> +{
> +	page = __page_pool_put_page(pool, page, dma_sync_size, allow_direct);
> +	if (page && !page_pool_recycle_in_ring(pool, page)) {
> +		/* Cache full, fallback to free pages */
> +		page_pool_return_page(pool, page);
> +	}
>  }
>  EXPORT_SYMBOL(page_pool_put_page);
>  
> +/* Caller must not use data area after call, as this function overwrites it */
> +void page_pool_put_page_bulk(struct page_pool *pool, void **data,
> +			     int count)
> +{
> +	int i, bulk_len = 0, pa_len = 0;
> +
> +	for (i = 0; i < count; i++) {
> +		struct page *page = virt_to_head_page(data[i]);
> +
> +		page = __page_pool_put_page(pool, page, -1, false);
> +		/* Approved for bulk recycling in ptr_ring cache */
> +		if (page)
> +			data[bulk_len++] = page;
> +	}
> +
> +	if (!bulk_len)
> +		return;
> +
> +	/* Bulk producer into ptr_ring page_pool cache */
> +	page_pool_ring_lock(pool);
> +	for (i = 0; i < bulk_len; i++) {
> +		if (__ptr_ring_produce(&pool->ring, data[i]))
> +			data[pa_len++] = data[i];
> +	}
> +	page_pool_ring_unlock(pool);
> +
> +	/* ptr_ring cache full, free pages outside producer lock since
> +	 * put_page() with refcnt == 1 can be an expensive operation
> +	 */
> +	for (i = 0; i < pa_len; i++)
> +		page_pool_return_page(pool, data[i]);
> +}
> +EXPORT_SYMBOL(page_pool_put_page_bulk);


-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer

Re: [PATCH v4 net-next 1/5] net: xdp: introduce bulking for xdp tx return path

[Jesper Dangaard Brouer]

On Fri,  6 Nov 2020 19:19:07 +0100
Lorenzo Bianconi <lorenzo@kernel.org> wrote:

> +void xdp_return_frame_bulk(struct xdp_frame *xdpf,
> +			   struct xdp_frame_bulk *bq)
> +{
> +	struct xdp_mem_info *mem = &xdpf->mem;
> +	struct xdp_mem_allocator *xa;
> +
> +	if (mem->type != MEM_TYPE_PAGE_POOL) {
> +		__xdp_return(xdpf->data, &xdpf->mem, false);
> +		return;
> +	}
> +
> +	rcu_read_lock();

This rcu_read_lock() shows up on my performance benchmarking, and is
unnecessary for the fast-path usage, as in most drivers DMA-TX
completion already holds the rcu_read_lock.

> +	xa = bq->xa;
> +	if (unlikely(!xa)) {
> +		xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
> +		bq->count = 0;
> +		bq->xa = xa;
> +	}
> +
> +	if (bq->count == XDP_BULK_QUEUE_SIZE)
> +		xdp_flush_frame_bulk(bq);
> +
> +	if (mem->id != xa->mem.id) {
> +		xdp_flush_frame_bulk(bq);
> +		bq->xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
> +	}
> +
> +	bq->q[bq->count++] = xdpf->data;
> +
> +	rcu_read_unlock();
> +}
> +EXPORT_SYMBOL_GPL(xdp_return_frame_bulk);



-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer