netdev - [PATCH net-next 1/4] net: xdp: introduce bulking for xdp tx return path

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Date:   Tue, 27 Oct 2020 20:04:07 +0100
From:   Lorenzo Bianconi <lorenzo@...nel.org>
To:     netdev@...r.kernel.org
Cc:     bpf@...r.kernel.org, lorenzo.bianconi@...hat.com,
        davem@...emloft.net, kuba@...nel.org, brouer@...hat.com,
        ilias.apalodimas@...aro.org
Subject: [PATCH net-next 1/4] net: xdp: introduce bulking for xdp tx return path

Introduce bulking capability in xdp tx return path (XDP_REDIRECT).
xdp_return_frame is usually run inside the driver NAPI tx completion
loop so it is possible batch it.
Current implementation considers only page_pool memory model.
Convert mvneta driver to xdp_return_frame_bulk APIs.

Suggested-by: Jesper Dangaard Brouer <brouer@...hat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@...nel.org>
---
 drivers/net/ethernet/marvell/mvneta.c |  5 ++-
 include/net/xdp.h                     |  9 +++++
 net/core/xdp.c                        | 51 +++++++++++++++++++++++++++
 3 files changed, 64 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);
 }
diff --git a/include/net/xdp.h b/include/net/xdp.h
index 3814fb631d52..9567110845ef 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 {
+	void *q[XDP_BULK_QUEUE_SIZE];
+	int count;
+	void *xa;
+};
 
 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
diff --git a/net/core/xdp.c b/net/core/xdp.c
index 48aba933a5a8..93eabd789246 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -380,6 +380,57 @@ void xdp_return_frame_rx_napi(struct xdp_frame *xdpf)
 }
 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))
+		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, *nxa;
+
+	if (mem->type != MEM_TYPE_PAGE_POOL) {
+		__xdp_return(xdpf->data, &xdpf->mem, false);
+		return;
+	}
+
+	rcu_read_lock();
+
+	xa = bq->xa;
+	if (unlikely(!xa || mem->id != xa->mem.id)) {
+		nxa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
+		if (unlikely(!xa)) {
+			bq->count = 0;
+			bq->xa = nxa;
+			xa = nxa;
+		}
+	}
+
+	if (mem->id != xa->mem.id || bq->count == XDP_BULK_QUEUE_SIZE)
+		xdp_flush_frame_bulk(bq);
+
+	bq->q[bq->count++] = xdpf->data;
+	if (mem->id != xa->mem.id)
+		bq->xa = nxa;
+
+	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