From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C3F93C433B4 for ; Thu, 13 May 2021 11:44:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 928B161183 for ; Thu, 13 May 2021 11:44:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231410AbhEMLpP (ORCPT ); Thu, 13 May 2021 07:45:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34464 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233407AbhEMLox (ORCPT ); Thu, 13 May 2021 07:44:53 -0400 Received: from plekste.mt.lv (bute.mt.lv [IPv6:2a02:610:7501:2000::195]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 91918C061763; Thu, 13 May 2021 04:43:42 -0700 (PDT) Received: from [2a02:610:7501:feff:1ccf:41ff:fe50:18b9] (helo=localhost.localdomain) by plekste.mt.lv with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.89) (envelope-from ) id 1lh9kb-0007HF-BQ; Thu, 13 May 2021 14:43:33 +0300 From: Gatis Peisenieks To: chris.snook@gmail.com, davem@davemloft.net, kuba@kernel.org, hkallweit1@gmail.com, jesse.brandeburg@intel.com, dchickles@marvell.com, tully@mikrotik.com, eric.dumazet@gmail.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Gatis Peisenieks Subject: [PATCH net-next v2 2/5] atl1c: improve performance by avoiding unnecessary pcie writes on xmit Date: Thu, 13 May 2021 14:43:23 +0300 Message-Id: <20210513114326.699663-3-gatis@mikrotik.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210513114326.699663-1-gatis@mikrotik.com> References: <20210513114326.699663-1-gatis@mikrotik.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The kernel has xmit_more facility that hints the networking driver xmit path about whether more packets are coming soon. This information can be used to avoid unnecessary expensive PCIe transaction per tx packet. Max TX pps on Mikrotik 10/25G NIC in a Threadripper 3960X system improved from 1150Kpps to 1700Kpps. Testing L2 forwarding on AR8151 hardware did not reveal a measurable increase in latency. Signed-off-by: Gatis Peisenieks --- drivers/net/ethernet/atheros/atl1c/atl1c_main.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/net/ethernet/atheros/atl1c/atl1c_main.c b/drivers/net/ethernet/atheros/atl1c/atl1c_main.c index 28c30d5288e4..08a0f49e03ce 100644 --- a/drivers/net/ethernet/atheros/atl1c/atl1c_main.c +++ b/drivers/net/ethernet/atheros/atl1c/atl1c_main.c @@ -2211,8 +2211,8 @@ static int atl1c_tx_map(struct atl1c_adapter *adapter, return -1; } -static void atl1c_tx_queue(struct atl1c_adapter *adapter, struct sk_buff *skb, - struct atl1c_tpd_desc *tpd, enum atl1c_trans_queue type) +static void atl1c_tx_queue(struct atl1c_adapter *adapter, + enum atl1c_trans_queue type) { struct atl1c_tpd_ring *tpd_ring = &adapter->tpd_ring[type]; u16 reg; @@ -2238,6 +2238,7 @@ static netdev_tx_t atl1c_xmit_frame(struct sk_buff *skb, if (atl1c_tpd_avail(adapter, type) < tpd_req) { /* no enough descriptor, just stop queue */ + atl1c_tx_queue(adapter, type); netif_stop_queue(netdev); return NETDEV_TX_BUSY; } @@ -2246,6 +2247,7 @@ static netdev_tx_t atl1c_xmit_frame(struct sk_buff *skb, /* do TSO and check sum */ if (atl1c_tso_csum(adapter, skb, &tpd, type) != 0) { + atl1c_tx_queue(adapter, type); dev_kfree_skb_any(skb); return NETDEV_TX_OK; } @@ -2270,8 +2272,10 @@ static netdev_tx_t atl1c_xmit_frame(struct sk_buff *skb, atl1c_tx_rollback(adapter, tpd, type); dev_kfree_skb_any(skb); } else { - netdev_sent_queue(adapter->netdev, skb->len); - atl1c_tx_queue(adapter, skb, tpd, type); + bool more = netdev_xmit_more(); + + if (__netdev_sent_queue(adapter->netdev, skb->len, more)) + atl1c_tx_queue(adapter, type); } return NETDEV_TX_OK; -- 2.31.1