[PATCH v2] net: stmmac: add BQL support

Subsystems: networking drivers, stmmac ethernet driver, the rest

STALE4210d

4 messages, 4 authors, 2015-01-27 · open the first message on its own page

[PATCH v2] net: stmmac: add BQL support

From: Beniamino Galvani <hidden>
Date: 2015-01-21 18:08:34

Add support for Byte Queue Limits to the STMicro MAC driver.

Tested on a Amlogic S802 quad Cortex-A9 board, where the use of BQL
decreases the latency of a high priority ping from ~12ms to ~1ms when
the 100Mbit link is saturated by 20 TCP streams.

Signed-off-by: Beniamino Galvani <redacted>
---
Changes since v1:
 - don't access skb->len after the start of DMA transmission in
   stmmac_xmit(), to avoid potential use after free in case tx_lock is
   removed in the future

 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 118a427..1d74313 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -1097,6 +1097,7 @@ static int init_dma_desc_rings(struct net_device *dev, gfp_t flags)
 
 	priv->dirty_tx = 0;
 	priv->cur_tx = 0;
+	netdev_reset_queue(priv->dev);
 
 	stmmac_clear_descriptors(priv);

@@ -1300,6 +1301,7 @@ static void stmmac_dma_operation_mode(struct stmmac_priv *priv)
 static void stmmac_tx_clean(struct stmmac_priv *priv)
 {
 	unsigned int txsize = priv->dma_tx_size;
+	unsigned int bytes_compl = 0, pkts_compl = 0;
 
 	spin_lock(&priv->tx_lock);

@@ -1356,6 +1358,8 @@ static void stmmac_tx_clean(struct stmmac_priv *priv)
 		priv->hw->mode->clean_desc3(priv, p);
 
 		if (likely(skb != NULL)) {
+			pkts_compl++;
+			bytes_compl += skb->len;
 			dev_consume_skb_any(skb);
 			priv->tx_skbuff[entry] = NULL;
 		}

@@ -1364,6 +1368,9 @@ static void stmmac_tx_clean(struct stmmac_priv *priv)
 
 		priv->dirty_tx++;
 	}
+
+	netdev_completed_queue(priv->dev, pkts_compl, bytes_compl);
+
 	if (unlikely(netif_queue_stopped(priv->dev) &&
 		     stmmac_tx_avail(priv) > STMMAC_TX_THRESH(priv))) {
 		netif_tx_lock(priv->dev);

@@ -1418,6 +1425,7 @@ static void stmmac_tx_err(struct stmmac_priv *priv)
 						     (i == txsize - 1));
 	priv->dirty_tx = 0;
 	priv->cur_tx = 0;
+	netdev_reset_queue(priv->dev);
 	priv->hw->dma->start_tx(priv->ioaddr);
 
 	priv->dev->stats.tx_errors++;

@@ -2048,6 +2056,7 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
 	if (!priv->hwts_tx_en)
 		skb_tx_timestamp(skb);
 
+	netdev_sent_queue(dev, skb->len);
 	priv->hw->dma->enable_dma_transmission(priv->ioaddr);
 
 	spin_unlock(&priv->tx_lock);

-- 
2.1.4

Re: [PATCH v2] net: stmmac: add BQL support

From: Eric Dumazet <hidden>
Date: 2015-01-21 18:37:20

On Wed, 2015-01-21 at 19:07 +0100, Beniamino Galvani wrote:

Add support for Byte Queue Limits to the STMicro MAC driver.

Tested on a Amlogic S802 quad Cortex-A9 board, where the use of BQL
decreases the latency of a high priority ping from ~12ms to ~1ms when
the 100Mbit link is saturated by 20 TCP streams.

Signed-off-by: Beniamino Galvani <redacted>
---
Changes since v1:
 - don't access skb->len after the start of DMA transmission in
   stmmac_xmit(), to avoid potential use after free in case tx_lock is
   removed in the future

 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 9 +++++++++
 1 file changed, 9 insertions(+)

Reviewed-by: Eric Dumazet <edumazet@google.com>

Thanks !

Re: [PATCH v2] net: stmmac: add BQL support

From: Giuseppe CAVALLARO <hidden>
Date: 2015-01-22 11:58:18

On 1/21/2015 7:07 PM, Beniamino Galvani wrote:

Add support for Byte Queue Limits to the STMicro MAC driver.

Tested on a Amlogic S802 quad Cortex-A9 board, where the use of BQL
decreases the latency of a high priority ping from ~12ms to ~1ms when
the 100Mbit link is saturated by 20 TCP streams.

Signed-off-by: Beniamino Galvani <redacted>


Ciao Beniamino

thx for the patch, I also see some improvements on my side

Acked-by: Giuseppe Cavallaro <redacted>

quoted hunk

---
Changes since v1:
  - don't access skb->len after the start of DMA transmission in
    stmmac_xmit(), to avoid potential use after free in case tx_lock is
    removed in the future

  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 9 +++++++++
  1 file changed, 9 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 118a427..1d74313 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -1097,6 +1097,7 @@ static int init_dma_desc_rings(struct net_device *dev, gfp_t flags)

  	priv->dirty_tx = 0;
  	priv->cur_tx = 0;
+	netdev_reset_queue(priv->dev);

  	stmmac_clear_descriptors(priv);

@@ -1300,6 +1301,7 @@ static void stmmac_dma_operation_mode(struct stmmac_priv *priv)
  static void stmmac_tx_clean(struct stmmac_priv *priv)
  {
  	unsigned int txsize = priv->dma_tx_size;
+	unsigned int bytes_compl = 0, pkts_compl = 0;

  	spin_lock(&priv->tx_lock);

@@ -1356,6 +1358,8 @@ static void stmmac_tx_clean(struct stmmac_priv *priv)
  		priv->hw->mode->clean_desc3(priv, p);

  		if (likely(skb != NULL)) {
+			pkts_compl++;
+			bytes_compl += skb->len;
  			dev_consume_skb_any(skb);
  			priv->tx_skbuff[entry] = NULL;
  		}

@@ -1364,6 +1368,9 @@ static void stmmac_tx_clean(struct stmmac_priv *priv)

  		priv->dirty_tx++;
  	}
+
+	netdev_completed_queue(priv->dev, pkts_compl, bytes_compl);
+
  	if (unlikely(netif_queue_stopped(priv->dev) &&
  		     stmmac_tx_avail(priv) > STMMAC_TX_THRESH(priv))) {
  		netif_tx_lock(priv->dev);

@@ -1418,6 +1425,7 @@ static void stmmac_tx_err(struct stmmac_priv *priv)
  						     (i == txsize - 1));
  	priv->dirty_tx = 0;
  	priv->cur_tx = 0;
+	netdev_reset_queue(priv->dev);
  	priv->hw->dma->start_tx(priv->ioaddr);

  	priv->dev->stats.tx_errors++;

@@ -2048,6 +2056,7 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
  	if (!priv->hwts_tx_en)
  		skb_tx_timestamp(skb);

+	netdev_sent_queue(dev, skb->len);
  	priv->hw->dma->enable_dma_transmission(priv->ioaddr);

  	spin_unlock(&priv->tx_lock);

Re: [PATCH v2] net: stmmac: add BQL support

From: David Miller <davem@davemloft.net>
Date: 2015-01-27 00:39:06

From: Beniamino Galvani <redacted>
Date: Wed, 21 Jan 2015 19:07:27 +0100

Add support for Byte Queue Limits to the STMicro MAC driver.

Tested on a Amlogic S802 quad Cortex-A9 board, where the use of BQL
decreases the latency of a high priority ping from ~12ms to ~1ms when
the 100Mbit link is saturated by 20 TCP streams.

Signed-off-by: Beniamino Galvani <redacted>

Applied.

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