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| author | Ilias Apalodimas <ilias.apalodimas@linaro.org> | 2018-08-10 09:12:38 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-08-11 12:11:36 -0700 |
| commit | 63ae7949e94aad607c24d00b8ce3f5661c0a1e9d (patch) | |
| tree | 7be4a38062a08e091631a1ad2ec9d2e962bf3b9b /drivers/net/ethernet | |
| parent | 78aca3bbee880ea4d6f30d603c057058b03bdc77 (diff) | |
| download | linux-63ae7949e94aad607c24d00b8ce3f5661c0a1e9d.tar.gz linux-63ae7949e94aad607c24d00b8ce3f5661c0a1e9d.tar.bz2 linux-63ae7949e94aad607c24d00b8ce3f5661c0a1e9d.zip | |
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>
Diffstat (limited to 'drivers/net/ethernet')
| -rw-r--r-- | drivers/net/ethernet/socionext/netsec.c | 25 |
1 files changed, 10 insertions, 15 deletions
diff --git a/drivers/net/ethernet/socionext/netsec.c b/drivers/net/ethernet/socionext/netsec.c index 01589b6982e4..334b6189b011 100644 --- a/drivers/net/ethernet/socionext/netsec.c +++ b/drivers/net/ethernet/socionext/netsec.c @@ -642,8 +642,6 @@ static struct sk_buff *netsec_get_rx_pkt_data(struct netsec_priv *priv, tmp_skb = netsec_alloc_skb(priv, &td); - dma_rmb(); - tail = dring->tail; if (!tmp_skb) { @@ -657,8 +655,6 @@ static struct sk_buff *netsec_get_rx_pkt_data(struct netsec_priv *priv, /* move tail ahead */ dring->tail = (dring->tail + 1) % DESC_NUM; - dring->pkt_cnt--; - return skb; } @@ -731,25 +727,24 @@ static int netsec_process_rx(struct netsec_priv *priv, int budget) struct netsec_desc_ring *dring = &priv->desc_ring[NETSEC_RING_RX]; struct net_device *ndev = priv->ndev; struct netsec_rx_pkt_info rx_info; - int done = 0, rx_num = 0; + int done = 0; struct netsec_desc desc; struct sk_buff *skb; u16 len; while (done < budget) { - if (!rx_num) { - rx_num = netsec_read(priv, NETSEC_REG_NRM_RX_PKTCNT); - dring->pkt_cnt += rx_num; + u16 idx = dring->tail; + struct netsec_de *de = dring->vaddr + (DESC_SZ * idx); - /* move head 'rx_num' */ - dring->head = (dring->head + rx_num) % DESC_NUM; + if (de->attr & (1U << NETSEC_RX_PKT_OWN_FIELD)) + break; - rx_num = dring->pkt_cnt; - if (!rx_num) - break; - } + /* This barrier is needed to keep us from reading + * any other fields out of the netsec_de until we have + * verified the descriptor has been written back + */ + dma_rmb(); done++; - rx_num--; skb = netsec_get_rx_pkt_data(priv, &rx_info, &desc, &len); if (unlikely(!skb) || rx_info.err_flag) { netif_err(priv, drv, priv->ndev, |