[Intel-wired-lan] [RFC PATCH] i40e: enable PCIe relax ordering for SPARC

Tushar Dave tushar.n.dave at oracle.com
Mon Dec 5 17:07:07 UTC 2016


Unlike previous generation NIC (e.g. ixgbe) i40e doesn't seem to have
standard CSR where PCIe relaxed ordering can be set. Without PCIe relax
ordering enabled, i40e performance is significantly low on SPARC.

This patch sets PCIe relax ordering for SPARC arch by setting dma attr
DMA_ATTR_WEAK_ORDERING for every tx and rx DMA map/unmap.
This has shown 10x increase in performance numbers.

e.g.
iperf TCP test with 10 threads on SPARC S7

Test 1: Without this patch

[root at brm-snt1-03 net]# iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
[  4] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 40926
[  5] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 40934
[  6] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 40930
[  7] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 40928
[  8] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 40922
[  9] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 40932
[ 10] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 40920
[ 11] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 40924
[ 14] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 40982
[ 12] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 40980
[ ID] Interval       Transfer     Bandwidth
[  4]  0.0-20.0 sec   566 MBytes   237 Mbits/sec
[  5]  0.0-20.0 sec   532 MBytes   223 Mbits/sec
[  6]  0.0-20.0 sec   537 MBytes   225 Mbits/sec
[  8]  0.0-20.0 sec   546 MBytes   229 Mbits/sec
[ 11]  0.0-20.0 sec   592 MBytes   248 Mbits/sec
[  7]  0.0-20.0 sec   539 MBytes   226 Mbits/sec
[  9]  0.0-20.0 sec   572 MBytes   240 Mbits/sec
[ 10]  0.0-20.0 sec   604 MBytes   253 Mbits/sec
[ 14]  0.0-20.0 sec   567 MBytes   238 Mbits/sec
[ 12]  0.0-20.0 sec   511 MBytes   214 Mbits/sec
[SUM]  0.0-20.0 sec  5.44 GBytes  2.33 Gbits/sec

Test 2: with this patch:

[root at brm-snt1-03 net]# iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
TCP: request_sock_TCP: Possible SYN flooding on port 5001. Sending
cookies.  Check SNMP counters.
[  4] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 46876
[  5] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 46874
[  6] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 46872
[  7] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 46880
[  8] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 46878
[  9] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 46884
[ 10] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 46886
[ 11] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 46890
[ 12] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 46888
[ 13] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 46882
[ ID] Interval       Transfer     Bandwidth
[  4]  0.0-20.0 sec  7.45 GBytes  3.19 Gbits/sec
[  5]  0.0-20.0 sec  7.48 GBytes  3.21 Gbits/sec
[  7]  0.0-20.0 sec  7.34 GBytes  3.15 Gbits/sec
[  8]  0.0-20.0 sec  7.42 GBytes  3.18 Gbits/sec
[  9]  0.0-20.0 sec  7.24 GBytes  3.11 Gbits/sec
[ 10]  0.0-20.0 sec  7.40 GBytes  3.17 Gbits/sec
[ 12]  0.0-20.0 sec  7.49 GBytes  3.21 Gbits/sec
[  6]  0.0-20.0 sec  7.30 GBytes  3.13 Gbits/sec
[ 11]  0.0-20.0 sec  7.44 GBytes  3.19 Gbits/sec
[ 13]  0.0-20.0 sec  7.22 GBytes  3.10 Gbits/sec
[SUM]  0.0-20.0 sec  73.8 GBytes  31.6 Gbits/sec

NOTE: In my testing, this patch does _not_ show any harm to i40e
performance numbers on x86.

Signed-off-by: Tushar Dave <tushar.n.dave at oracle.com>
---
 drivers/net/ethernet/intel/i40e/i40e_txrx.c | 69 ++++++++++++++++++++---------
 drivers/net/ethernet/intel/i40e/i40e_txrx.h |  1 +
 2 files changed, 49 insertions(+), 21 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index 6287bf6..800dca7 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -551,15 +551,17 @@ static void i40e_unmap_and_free_tx_resource(struct i40e_ring *ring,
 		else
 			dev_kfree_skb_any(tx_buffer->skb);
 		if (dma_unmap_len(tx_buffer, len))
-			dma_unmap_single(ring->dev,
-					 dma_unmap_addr(tx_buffer, dma),
-					 dma_unmap_len(tx_buffer, len),
-					 DMA_TO_DEVICE);
+			dma_unmap_single_attrs(ring->dev,
+					       dma_unmap_addr(tx_buffer, dma),
+					       dma_unmap_len(tx_buffer, len),
+					       DMA_TO_DEVICE,
+					       ring->dma_attrs);
 	} else if (dma_unmap_len(tx_buffer, len)) {
-		dma_unmap_page(ring->dev,
-			       dma_unmap_addr(tx_buffer, dma),
-			       dma_unmap_len(tx_buffer, len),
-			       DMA_TO_DEVICE);
+		dma_unmap_single_attrs(ring->dev,
+				       dma_unmap_addr(tx_buffer, dma),
+				       dma_unmap_len(tx_buffer, len),
+				       DMA_TO_DEVICE,
+				       ring->dma_attrs);
 	}
 
 	tx_buffer->next_to_watch = NULL;
@@ -662,6 +664,8 @@ static bool i40e_clean_tx_irq(struct i40e_vsi *vsi,
 	struct i40e_tx_buffer *tx_buf;
 	struct i40e_tx_desc *tx_head;
 	struct i40e_tx_desc *tx_desc;
+	dma_addr_t addr;
+	size_t size;
 	unsigned int total_bytes = 0, total_packets = 0;
 	unsigned int budget = vsi->work_limit;
 
@@ -696,10 +700,11 @@ static bool i40e_clean_tx_irq(struct i40e_vsi *vsi,
 		napi_consume_skb(tx_buf->skb, napi_budget);
 
 		/* unmap skb header data */
-		dma_unmap_single(tx_ring->dev,
-				 dma_unmap_addr(tx_buf, dma),
-				 dma_unmap_len(tx_buf, len),
-				 DMA_TO_DEVICE);
+		dma_unmap_single_attrs(tx_ring->dev,
+				       dma_unmap_addr(tx_buf, dma),
+				       dma_unmap_len(tx_buf, len),
+				       DMA_TO_DEVICE,
+				       tx_ring->dma_attrs);
 
 		/* clear tx_buffer data */
 		tx_buf->skb = NULL;
@@ -717,12 +722,15 @@ static bool i40e_clean_tx_irq(struct i40e_vsi *vsi,
 				tx_desc = I40E_TX_DESC(tx_ring, 0);
 			}
 
+			addr = dma_unmap_addr(tx_buf, dma);
+			size = dma_unmap_len(tx_buf, len);
 			/* unmap any remaining paged data */
 			if (dma_unmap_len(tx_buf, len)) {
-				dma_unmap_page(tx_ring->dev,
-					       dma_unmap_addr(tx_buf, dma),
-					       dma_unmap_len(tx_buf, len),
-					       DMA_TO_DEVICE);
+				dma_unmap_single_attrs(tx_ring->dev,
+						       addr,
+						       size,
+						       DMA_TO_DEVICE,
+						       tx_ring->dma_attrs);
 				dma_unmap_len_set(tx_buf, len, 0);
 			}
 		}
@@ -1010,6 +1018,11 @@ int i40e_setup_tx_descriptors(struct i40e_ring *tx_ring)
 	 */
 	tx_ring->size += sizeof(u32);
 	tx_ring->size = ALIGN(tx_ring->size, 4096);
+#ifdef CONFIG_SPARC
+	tx_ring->dma_attrs = DMA_ATTR_WEAK_ORDERING;
+#else
+	tx_ring->dma_attrs = 0;
+#endif
 	tx_ring->desc = dma_alloc_coherent(dev, tx_ring->size,
 					   &tx_ring->dma, GFP_KERNEL);
 	if (!tx_ring->desc) {
@@ -1053,7 +1066,11 @@ void i40e_clean_rx_ring(struct i40e_ring *rx_ring)
 		if (!rx_bi->page)
 			continue;
 
-		dma_unmap_page(dev, rx_bi->dma, PAGE_SIZE, DMA_FROM_DEVICE);
+		dma_unmap_single_attrs(dev,
+				       rx_bi->dma,
+				       PAGE_SIZE,
+				       DMA_FROM_DEVICE,
+				       rx_ring->dma_attrs);
 		__free_pages(rx_bi->page, 0);
 
 		rx_bi->page = NULL;
@@ -1113,6 +1130,11 @@ int i40e_setup_rx_descriptors(struct i40e_ring *rx_ring)
 	/* Round up to nearest 4K */
 	rx_ring->size = rx_ring->count * sizeof(union i40e_32byte_rx_desc);
 	rx_ring->size = ALIGN(rx_ring->size, 4096);
+#ifdef CONFIG_SPARC
+	rx_ring->dma_attrs = DMA_ATTR_WEAK_ORDERING;
+#else
+	rx_ring->dma_attrs = 0;
+#endif
 	rx_ring->desc = dma_alloc_coherent(dev, rx_ring->size,
 					   &rx_ring->dma, GFP_KERNEL);
 
@@ -1182,7 +1204,8 @@ static bool i40e_alloc_mapped_page(struct i40e_ring *rx_ring,
 	}
 
 	/* map page for use */
-	dma = dma_map_page(rx_ring->dev, page, 0, PAGE_SIZE, DMA_FROM_DEVICE);
+	dma = dma_map_single_attrs(rx_ring->dev, page_address(page), PAGE_SIZE,
+				   DMA_FROM_DEVICE, rx_ring->dma_attrs);
 
 	/* if mapping failed free memory back to system since
 	 * there isn't much point in holding memory we can't use
@@ -1695,8 +1718,11 @@ struct sk_buff *i40e_fetch_rx_buffer(struct i40e_ring *rx_ring,
 		rx_ring->rx_stats.page_reuse_count++;
 	} else {
 		/* we are not reusing the buffer so unmap it */
-		dma_unmap_page(rx_ring->dev, rx_buffer->dma, PAGE_SIZE,
-			       DMA_FROM_DEVICE);
+		dma_unmap_single_attrs(rx_ring->dev,
+				       rx_buffer->dma,
+				       PAGE_SIZE,
+				       DMA_FROM_DEVICE,
+				       rx_ring->dma_attrs);
 	}
 
 	/* clear contents of buffer_info */
@@ -2737,7 +2763,8 @@ static inline void i40e_tx_map(struct i40e_ring *tx_ring, struct sk_buff *skb,
 	first->skb = skb;
 	first->tx_flags = tx_flags;
 
-	dma = dma_map_single(tx_ring->dev, skb->data, size, DMA_TO_DEVICE);
+	dma = dma_map_single_attrs(tx_ring->dev, skb->data, size,
+				   DMA_TO_DEVICE, tx_ring->dma_attrs);
 
 	tx_desc = I40E_TX_DESC(tx_ring, i);
 	tx_bi = first;
diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.h b/drivers/net/ethernet/intel/i40e/i40e_txrx.h
index 5088405..9a86212 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.h
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.h
@@ -327,6 +327,7 @@ struct i40e_ring {
 
 	unsigned int size;		/* length of descriptor ring in bytes */
 	dma_addr_t dma;			/* physical address of ring */
+	unsigned long dma_attrs;	/* DMA attributes */
 
 	struct i40e_vsi *vsi;		/* Backreference to associated VSI */
 	struct i40e_q_vector *q_vector;	/* Backreference to associated vector */
-- 
1.9.1



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