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Commit 120e87f9 authored by Giuseppe Cavallaro's avatar Giuseppe Cavallaro Committed by David S. Miller
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stmmac: tune rx copy via threshold. 



There is a threshold now used to also limit the skb allocation
when use zero-copy. This is to avoid that there are incoherence
in the ring due to a failure on skb allocation under very
aggressive testing and under low memory conditions.

Signed-off-by: default avatarGiuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: default avatarAlexandre TORGUE <alexandre.torgue@st.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 22ad3838

drivers/net/ethernet/stmicro/stmmac/stmmac.h

+1 −0
Original line number Diff line number Diff line
@@ -75,6 +75,7 @@ struct stmmac_priv { 
	unsigned int dirty_rx;

	unsigned int dma_buf_sz;

	unsigned int rx_copybreak;

	unsigned int rx_zeroc_thresh;

	u32 rx_riwt;

	int hwts_rx_en;

	dma_addr_t *rx_skbuff_dma;

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

+24 −2
Original line number Diff line number Diff line
@@ -72,6 +72,7 @@ module_param(phyaddr, int, S_IRUGO); 
MODULE_PARM_DESC(phyaddr, "Physical device address");



#define STMMAC_TX_THRESH	(DMA_TX_SIZE / 4)

#define STMMAC_RX_THRESH	(DMA_RX_SIZE / 4)



static int flow_ctrl = FLOW_OFF;

module_param(flow_ctrl, int, S_IRUGO | S_IWUSR);
@@ -2138,6 +2139,14 @@ static void stmmac_rx_vlan(struct net_device *dev, struct sk_buff *skb) 
}





static inline int stmmac_rx_threshold_count(struct stmmac_priv *priv)

{

	if (priv->rx_zeroc_thresh < STMMAC_RX_THRESH)

		return 0;



	return 1;

}



/**

 * stmmac_rx_refill - refill used skb preallocated buffers

 * @priv: driver private structure
@@ -2162,8 +2171,15 @@ static inline void stmmac_rx_refill(struct stmmac_priv *priv) 
			struct sk_buff *skb;



			skb = netdev_alloc_skb_ip_align(priv->dev, bfsize);

			if (unlikely(!skb))

			if (unlikely(!skb)) {

				/* so for a while no zero-copy! */

				priv->rx_zeroc_thresh = STMMAC_RX_THRESH;

				if (unlikely(net_ratelimit()))

					dev_err(priv->device,

						"fail to alloc skb entry %d\n",

						entry);

				break;

			}



			priv->rx_skbuff[entry] = skb;

			priv->rx_skbuff_dma[entry] =
@@ -2179,9 +2195,13 @@ static inline void stmmac_rx_refill(struct stmmac_priv *priv) 


			priv->hw->mode->refill_desc3(priv, p);



			if (priv->rx_zeroc_thresh > 0)

				priv->rx_zeroc_thresh--;



			if (netif_msg_rx_status(priv))

				pr_debug("\trefill entry #%d\n", entry);

		}



		wmb();

		priv->hw->desc->set_rx_owner(p);

		wmb();
@@ -2285,7 +2305,8 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit) 
						 frame_len, status);

			}



			if (unlikely(frame_len < priv->rx_copybreak)) {

			if (unlikely((frame_len < priv->rx_copybreak) ||

				     stmmac_rx_threshold_count(priv))) {

				skb = netdev_alloc_skb_ip_align(priv->dev,

								frame_len);

				if (unlikely(!skb)) {
@@ -2320,6 +2341,7 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit) 
				}

				prefetch(skb->data - NET_IP_ALIGN);

				priv->rx_skbuff[entry] = NULL;

				priv->rx_zeroc_thresh++;



				skb_put(skb, frame_len);

				dma_unmap_single(priv->device,