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net: socionext: Use descriptor info instead of MMIO reads on Rx
MMIO reads for remaining packets in queue occur (at least)twice per invocation of netsec_process_rx(). We can use the packet descriptor to identify if it's owned by the hardware and break out, avoiding the more expensive MMIO read operations. This has a ~2% increase on the pps of the Rx path when tested with 64byte packets Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -642,8 +642,6 @@ static struct sk_buff *netsec_get_rx_pkt_data(struct netsec_priv *priv,
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tmp_skb = netsec_alloc_skb(priv, &td);
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dma_rmb();
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tail = dring->tail;
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if (!tmp_skb) {
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@ -657,8 +655,6 @@ static struct sk_buff *netsec_get_rx_pkt_data(struct netsec_priv *priv,
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/* move tail ahead */
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dring->tail = (dring->tail + 1) % DESC_NUM;
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dring->pkt_cnt--;
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return skb;
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}
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@ -731,25 +727,24 @@ static int netsec_process_rx(struct netsec_priv *priv, int budget)
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struct netsec_desc_ring *dring = &priv->desc_ring[NETSEC_RING_RX];
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struct net_device *ndev = priv->ndev;
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struct netsec_rx_pkt_info rx_info;
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int done = 0, rx_num = 0;
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int done = 0;
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struct netsec_desc desc;
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struct sk_buff *skb;
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u16 len;
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while (done < budget) {
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if (!rx_num) {
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rx_num = netsec_read(priv, NETSEC_REG_NRM_RX_PKTCNT);
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dring->pkt_cnt += rx_num;
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u16 idx = dring->tail;
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struct netsec_de *de = dring->vaddr + (DESC_SZ * idx);
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/* move head 'rx_num' */
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dring->head = (dring->head + rx_num) % DESC_NUM;
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if (de->attr & (1U << NETSEC_RX_PKT_OWN_FIELD))
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break;
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rx_num = dring->pkt_cnt;
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if (!rx_num)
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break;
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}
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/* This barrier is needed to keep us from reading
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* any other fields out of the netsec_de until we have
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* verified the descriptor has been written back
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*/
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dma_rmb();
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done++;
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rx_num--;
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skb = netsec_get_rx_pkt_data(priv, &rx_info, &desc, &len);
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if (unlikely(!skb) || rx_info.err_flag) {
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netif_err(priv, drv, priv->ndev,
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