From patchwork Mon Sep 21 19:22:52 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Honnappa Nagarahalli X-Patchwork-Id: 313402 Delivered-To: patch@linaro.org Received: by 2002:a92:5ad1:0:0:0:0:0 with SMTP id b78csp3821956ilg; Mon, 21 Sep 2020 12:23:21 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwxegAnT9+O/9C1b4uLUrK08PUg+CTPDVAb6FTfPnAYSAs81xioHMioYUYYT3U4OOh+qXFo X-Received: by 2002:a05:6402:3076:: with SMTP id bs22mr457933edb.17.1600716201790; Mon, 21 Sep 2020 12:23:21 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1600716201; cv=none; d=google.com; s=arc-20160816; b=RnGFy2JL2I8juFOLtYpnuK2JJ7gd+ZZyqz1YrHNaO/I1ZtuoJ7F3iNKzOlYjuT87eX NsaxwVOzwLUzWZv8+WSSfC86etJ6jlB19NMgqtxFFnAA6uyOQJNxZ1omSwz9WGQsOFJF g25qyPYaImQwXrKmowTOCyq1tyU81UGGmzrAobPvyMo8uTxKqSTdP89zp+9GQkcA/hso 4sHBhczhzyQo/xubbUxjPirOMUL0sTSCUj2uca5eDpA4AmRRP3FGmSmkCbaQ8u/z9W8U Mq6epKb6xsSsYt67vaGvyDXrrgAG4uXJaUT9j4jPb67KShRcHlswKvM2tEtzwHGi1xYz YhbQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=sender:errors-to:list-subscribe:list-help:list-post:list-archive :list-unsubscribe:list-id:precedence:subject:references:in-reply-to :message-id:date:cc:to:from; bh=d/LhEQT0cIZp9REXQsZptyhwBX3iPeTPE0Ga7xFkG5s=; b=Kqg4bLvNzN5MnGII/SdWjGj0KDtmkRVewuLcDK51UKCuN0C+XlS6sKFNK44UljACzY LgRFMMNd361mz/ZtkjyKVQDIjSDXoze/gv3xl5L/5U1WxkEDssusGKavxp5dMRF/f6YJ XqT78K+c5JL1W05LjrkpDgE8vBikKm95qTbNvwi6Uy1mPQEh5pgK33Y6qIMNbZoQgYV6 7cq8kuyPsl9rYoUmC3XLnVB243HI/MJVo6/jd+kYRpKdyt5eRvvzVK6INe8M9gc7Tjp8 I2Ww66wR7eaZ35Do8HP6XUfY3ZuttkNx4z5xx2JUmDPQ0c13H3bCHmprvG7s4A7PnyB2 4pzQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of dev-bounces@dpdk.org designates 92.243.14.124 as permitted sender) smtp.mailfrom=dev-bounces@dpdk.org Return-Path: Received: from dpdk.org (dpdk.org. [92.243.14.124]) by mx.google.com with ESMTP id pg2si8912374ejb.328.2020.09.21.12.23.21; Mon, 21 Sep 2020 12:23:21 -0700 (PDT) Received-SPF: pass (google.com: domain of dev-bounces@dpdk.org designates 92.243.14.124 as permitted sender) client-ip=92.243.14.124; Authentication-Results: mx.google.com; spf=pass (google.com: domain of dev-bounces@dpdk.org designates 92.243.14.124 as permitted sender) smtp.mailfrom=dev-bounces@dpdk.org Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 1F2BC1DA54; Mon, 21 Sep 2020 21:23:16 +0200 (CEST) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by dpdk.org (Postfix) with ESMTP id AF2AA1D94B; Mon, 21 Sep 2020 21:23:12 +0200 (CEST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id F41291045; Mon, 21 Sep 2020 12:23:11 -0700 (PDT) Received: from qc2400f-1.austin.arm.com (qc2400f-1.austin.arm.com [10.118.12.27]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E3D513F718; Mon, 21 Sep 2020 12:23:11 -0700 (PDT) From: Honnappa Nagarahalli To: dev@dpdk.org, honnappa.nagarahalli@arm.com, phil.yang@arm.com, jgrajcia@cisco.com, ferruh.yigit@intel.com Cc: nd@arm.com, stable@dpdk.org Date: Mon, 21 Sep 2020 14:22:52 -0500 Message-Id: <20200921192254.20560-2-honnappa.nagarahalli@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200921192254.20560-1-honnappa.nagarahalli@arm.com> References: <20200921192254.20560-1-honnappa.nagarahalli@arm.com> Subject: [dpdk-dev] [PATCH 2/4] net/memif: relax the load of ring tail pointer for M2S ring X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" For M2S rings, ring->tail is updated by the sender and eth_memif_tx function is called in the context of sending thread. The loads in the sender do not need to synchronize with its own stores. Fixes: a2aafb9aa651 ("net/memif: optimize with one-way barrier") Cc: phil.yang@arm.com Cc: stable@dpdk.org Signed-off-by: Honnappa Nagarahalli Reviewed-by: Phil Yang --- drivers/net/memif/rte_eth_memif.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) -- 2.17.1 diff --git a/drivers/net/memif/rte_eth_memif.c b/drivers/net/memif/rte_eth_memif.c index fd7dbc53e..0d064c8fa 100644 --- a/drivers/net/memif/rte_eth_memif.c +++ b/drivers/net/memif/rte_eth_memif.c @@ -573,7 +573,13 @@ eth_memif_tx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts) n_free = ring_size - slot + __atomic_load_n(&ring->tail, __ATOMIC_ACQUIRE); } else { - slot = __atomic_load_n(&ring->tail, __ATOMIC_ACQUIRE); + /* For M2S queues ring->tail is updated by the sender and + * this function is called in the context of sending thread. + * The loads in the sender do not need to synchronize with + * its own stores. Hence, the following load can be a + * relaxed load. + */ + slot = __atomic_load_n(&ring->tail, __ATOMIC_RELAXED); n_free = __atomic_load_n(&ring->head, __ATOMIC_ACQUIRE) - slot; }