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authorIlias Apalodimas <ilias.apalodimas@linaro.org>2018-08-10 09:12:38 +0300
committerDavid S. Miller <davem@davemloft.net>2018-08-11 22:11:36 +0300
commit63ae7949e94aad607c24d00b8ce3f5661c0a1e9d (patch)
tree7be4a38062a08e091631a1ad2ec9d2e962bf3b9b /drivers/net/ethernet/socionext
parent78aca3bbee880ea4d6f30d603c057058b03bdc77 (diff)
downloadlinux-63ae7949e94aad607c24d00b8ce3f5661c0a1e9d.tar.xz
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/socionext')
-rw-r--r--drivers/net/ethernet/socionext/netsec.c25
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,