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Commit 1812063b authored by Michael S. Tsirkin's avatar Michael S. Tsirkin Committed by Roland Dreier
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IPoIB/cm: Improve small message bandwidth 



Avoid the overhead of freeing/reallocating and mapping/unmapping for
DMA pages that have not been written to by hardware.

Signed-off-by: default avatarMichael S. Tsirkin <mst@mellanox.co.il>
Signed-off-by: default avatarRoland Dreier <rolandd@cisco.com>
parent c9add6ec

drivers/infiniband/ulp/ipoib/ipoib_cm.c

+27 −19
Original line number Diff line number Diff line
@@ -65,14 +65,14 @@ struct ipoib_cm_id { 
static int ipoib_cm_tx_handler(struct ib_cm_id *cm_id,

			       struct ib_cm_event *event);



static void ipoib_cm_dma_unmap_rx(struct ipoib_dev_priv *priv,

static void ipoib_cm_dma_unmap_rx(struct ipoib_dev_priv *priv, int frags,

				  u64 mapping[IPOIB_CM_RX_SG])

{

	int i;



	ib_dma_unmap_single(priv->ca, mapping[0], IPOIB_CM_HEAD_SIZE, DMA_FROM_DEVICE);



	for (i = 0; i < IPOIB_CM_RX_SG - 1; ++i)

	for (i = 0; i < frags; ++i)

		ib_dma_unmap_single(priv->ca, mapping[i + 1], PAGE_SIZE, DMA_FROM_DEVICE);

}
@@ -90,7 +90,8 @@ static int ipoib_cm_post_receive(struct net_device *dev, int id) 
	ret = ib_post_srq_recv(priv->cm.srq, &priv->cm.rx_wr, &bad_wr);

	if (unlikely(ret)) {

		ipoib_warn(priv, "post srq failed for buf %d (%d)\n", id, ret);

		ipoib_cm_dma_unmap_rx(priv, priv->cm.srq_ring[id].mapping);

		ipoib_cm_dma_unmap_rx(priv, IPOIB_CM_RX_SG - 1,

				      priv->cm.srq_ring[id].mapping);

		dev_kfree_skb_any(priv->cm.srq_ring[id].skb);

		priv->cm.srq_ring[id].skb = NULL;

	}
@@ -98,7 +99,7 @@ static int ipoib_cm_post_receive(struct net_device *dev, int id) 
	return ret;

}



static int ipoib_cm_alloc_rx_skb(struct net_device *dev, int id,

static struct sk_buff *ipoib_cm_alloc_rx_skb(struct net_device *dev, int id, int frags,

					     u64 mapping[IPOIB_CM_RX_SG])

{

	struct ipoib_dev_priv *priv = netdev_priv(dev);
@@ -107,7 +108,7 @@ static int ipoib_cm_alloc_rx_skb(struct net_device *dev, int id, 


	skb = dev_alloc_skb(IPOIB_CM_HEAD_SIZE + 12);

	if (unlikely(!skb))

		return -ENOMEM;

		return NULL;



	/*

	 * IPoIB adds a 4 byte header. So we need 12 more bytes to align the
@@ -119,10 +120,10 @@ static int ipoib_cm_alloc_rx_skb(struct net_device *dev, int id, 
				       DMA_FROM_DEVICE);

	if (unlikely(ib_dma_mapping_error(priv->ca, mapping[0]))) {

		dev_kfree_skb_any(skb);

		return -EIO;

		return NULL;

	}



	for (i = 0; i < IPOIB_CM_RX_SG - 1; i++) {

	for (i = 0; i < frags; i++) {

		struct page *page = alloc_page(GFP_ATOMIC);



		if (!page)
@@ -136,7 +137,7 @@ static int ipoib_cm_alloc_rx_skb(struct net_device *dev, int id, 
	}



	priv->cm.srq_ring[id].skb = skb;

	return 0;

	return skb;



partial_error:
@@ -146,7 +147,7 @@ static int ipoib_cm_alloc_rx_skb(struct net_device *dev, int id, 
		ib_dma_unmap_single(priv->ca, mapping[i + 1], PAGE_SIZE, DMA_FROM_DEVICE);



	dev_kfree_skb_any(skb);

	return -ENOMEM;

	return NULL;

}



static struct ib_qp *ipoib_cm_create_rx_qp(struct net_device *dev,
@@ -309,7 +310,7 @@ static int ipoib_cm_rx_handler(struct ib_cm_id *cm_id, 
}

/* Adjust length of skb with fragments to match received data */

static void skb_put_frags(struct sk_buff *skb, unsigned int hdr_space,

			  unsigned int length)

			  unsigned int length, struct sk_buff *toskb)

{

	int i, num_frags;

	unsigned int size;
@@ -326,7 +327,7 @@ static void skb_put_frags(struct sk_buff *skb, unsigned int hdr_space, 


		if (length == 0) {

			/* don't need this page */

			__free_page(frag->page);

			skb_fill_page_desc(toskb, i, frag->page, 0, PAGE_SIZE);

			--skb_shinfo(skb)->nr_frags;

		} else {

			size = min(length, (unsigned) PAGE_SIZE);
@@ -344,10 +345,11 @@ void ipoib_cm_handle_rx_wc(struct net_device *dev, struct ib_wc *wc) 
{

	struct ipoib_dev_priv *priv = netdev_priv(dev);

	unsigned int wr_id = wc->wr_id & ~IPOIB_CM_OP_SRQ;

	struct sk_buff *skb;

	struct sk_buff *skb, *newskb;

	struct ipoib_cm_rx *p;

	unsigned long flags;

	u64 mapping[IPOIB_CM_RX_SG];

	int frags;



	ipoib_dbg_data(priv, "cm recv completion: id %d, op %d, status: %d\n",

		       wr_id, wc->opcode, wc->status);
@@ -383,7 +385,11 @@ void ipoib_cm_handle_rx_wc(struct net_device *dev, struct ib_wc *wc) 
		}

	}



	if (unlikely(ipoib_cm_alloc_rx_skb(dev, wr_id, mapping))) {

	frags = PAGE_ALIGN(wc->byte_len - min(wc->byte_len,

					      (unsigned)IPOIB_CM_HEAD_SIZE)) / PAGE_SIZE;



	newskb = ipoib_cm_alloc_rx_skb(dev, wr_id, frags, mapping);

	if (unlikely(!newskb)) {

		/*

		 * If we can't allocate a new RX buffer, dump

		 * this packet and reuse the old buffer.
@@ -393,13 +399,13 @@ void ipoib_cm_handle_rx_wc(struct net_device *dev, struct ib_wc *wc) 
		goto repost;

	}



	ipoib_cm_dma_unmap_rx(priv, priv->cm.srq_ring[wr_id].mapping);

	memcpy(priv->cm.srq_ring[wr_id].mapping, mapping, sizeof mapping);

	ipoib_cm_dma_unmap_rx(priv, frags, priv->cm.srq_ring[wr_id].mapping);

	memcpy(priv->cm.srq_ring[wr_id].mapping, mapping, (frags + 1) * sizeof *mapping);



	ipoib_dbg_data(priv, "received %d bytes, SLID 0x%04x\n",

		       wc->byte_len, wc->slid);



	skb_put_frags(skb, IPOIB_CM_HEAD_SIZE, wc->byte_len);

	skb_put_frags(skb, IPOIB_CM_HEAD_SIZE, wc->byte_len, newskb);



	skb->protocol = ((struct ipoib_header *) skb->data)->proto;

	skb->mac.raw = skb->data;
@@ -1193,7 +1199,8 @@ int ipoib_cm_dev_init(struct net_device *dev) 
	priv->cm.rx_wr.num_sge = IPOIB_CM_RX_SG;



	for (i = 0; i < ipoib_recvq_size; ++i) {

		if (ipoib_cm_alloc_rx_skb(dev, i, priv->cm.srq_ring[i].mapping)) {

		if (!ipoib_cm_alloc_rx_skb(dev, i, IPOIB_CM_RX_SG - 1,

					   priv->cm.srq_ring[i].mapping)) {

			ipoib_warn(priv, "failed to allocate receive buffer %d\n", i);

			ipoib_cm_dev_cleanup(dev);

			return -ENOMEM;
@@ -1228,7 +1235,8 @@ void ipoib_cm_dev_cleanup(struct net_device *dev) 
		return;

	for (i = 0; i < ipoib_recvq_size; ++i)

		if (priv->cm.srq_ring[i].skb) {

			ipoib_cm_dma_unmap_rx(priv, priv->cm.srq_ring[i].mapping);

			ipoib_cm_dma_unmap_rx(priv, IPOIB_CM_RX_SG - 1,

					      priv->cm.srq_ring[i].mapping);

			dev_kfree_skb_any(priv->cm.srq_ring[i].skb);

			priv->cm.srq_ring[i].skb = NULL;

		}