From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ilias Apalodimas Subject: [net-next, PATCH 1/2] net: socionext: Use descriptor info instead of MMIO reads on Rx Date: Thu, 9 Aug 2018 11:02:18 +0300 Message-ID: <1533801739-15312-1-git-send-email-ilias.apalodimas@linaro.org> Cc: arnd@arndb.de, Ilias Apalodimas To: netdev@vger.kernel.org, jaswinder.singh@linaro.org Return-path: Received: from mail-wr1-f66.google.com ([209.85.221.66]:33644 "EHLO mail-wr1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727786AbeHIK0J (ORCPT ); Thu, 9 Aug 2018 06:26:09 -0400 Received: by mail-wr1-f66.google.com with SMTP id g6-v6so4329523wrp.0 for ; Thu, 09 Aug 2018 01:02:30 -0700 (PDT) Sender: netdev-owner@vger.kernel.org List-ID: 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 --- drivers/net/ethernet/socionext/netsec.c | 19 +++++-------------- 1 file changed, 5 insertions(+), 14 deletions(-) diff --git a/drivers/net/ethernet/socionext/netsec.c b/drivers/net/ethernet/socionext/netsec.c index 01589b6..ae32909 100644 --- a/drivers/net/ethernet/socionext/netsec.c +++ b/drivers/net/ethernet/socionext/netsec.c @@ -657,8 +657,6 @@ 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 +729,18 @@ 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; - - /* move head 'rx_num' */ - dring->head = (dring->head + rx_num) % DESC_NUM; + u16 idx = dring->tail; + struct netsec_de *de = dring->vaddr + (DESC_SZ * idx); - rx_num = dring->pkt_cnt; - if (!rx_num) - break; - } + if (de->attr & (1U << NETSEC_RX_PKT_OWN_FIELD)) + break; 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, -- 2.7.4