From patchwork Mon Sep 21 19:22:54 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Honnappa Nagarahalli X-Patchwork-Id: 313404 Delivered-To: patch@linaro.org Received: by 2002:a92:5ad1:0:0:0:0:0 with SMTP id b78csp3822132ilg; Mon, 21 Sep 2020 12:23:37 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwQwHUusGlit8UOOtk+IxNucbEF6HMk5TC7YUBX7RcaM9vB8KMo1aUevfo3gYY/fgdOzN9T X-Received: by 2002:aa7:c61a:: with SMTP id h26mr451379edq.254.1600716217416; Mon, 21 Sep 2020 12:23:37 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1600716217; cv=none; d=google.com; s=arc-20160816; b=vbLI2RPRH8Pwv0e55yDd1Rklb5uILCuMM9TcUpzgj2hTcZrJ2XOyJVDkhFu9KGAiR/ 6fFHFsYCGyph5fjkp2CeLez9S+pKEyCTAAE0yb7ygArjsqUbeSOXA7YiQAAwNDG4UJtB 7IBPwJOLWUm+4mTbnjoLSo1P65GRoQ2wIpLJ+z9rGEX36odwAM9NsRRSHsuF02GbkxkM LxYDYsrryjpSKmNa2RRwLh6aJ+sl7aKk1FgVhgrhTy8Fey9W4WrM1D8iEZiMTF0h9s6R 9+rtQU3KZ74c82MPbyyWNT5XYKCmmdzMZEiUtE4xOcAtxmBcKROzYEj0WvlCnYY7XzXK t6mQ== 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=SoIKEg5P3IK1liWOIeo+X7rfyJRjxz9I+kcWzV9Nhjs=; b=ZrS4AWCKcjHknMxCiTCwQMj0weIngK+kci9oQ793sxQipEEuzdMk1Ef+esW7UTaoFq pYftZ9VP7fpZ7hSGRG+BT2ySTLCk+RFyssQu18CFPdzXY3NqQX/RJdDz30kH6Uouw6/F 5jQOsBpvVhxdYaxOWtt/k9PX3tmBxcPJjRzoJG+9GK//TI8wryNBpAznZg4TT5p6O1Ed Kei3FKULuemQR7gc6lnV8BNcHi/dbkm0tJWwHGceh6mSec/yJfbvsU5My9oogYUNbUyB 6qpy1VCuEbqqg32lFQlgLGRaJJkiNeVXrQUMug50zrvzJokqa9CRl9keV1Sir9LtFq9i ZW3w== 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 l25si8859475eje.688.2020.09.21.12.23.37; Mon, 21 Sep 2020 12:23:37 -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 3CC641DA7D; Mon, 21 Sep 2020 21:23:19 +0200 (CEST) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by dpdk.org (Postfix) with ESMTP id B181D1D9E2; Mon, 21 Sep 2020 21:23:14 +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 337F61045; Mon, 21 Sep 2020 12:23:14 -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 22FBC3F718; Mon, 21 Sep 2020 12:23:14 -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 14:22:54 -0500 Message-Id: <20200921192254.20560-4-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 4/4] net/memif: relax the load of ring head 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->head is updated by the receiver and eth_memif_rx function is called in the context of receiving 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 | 6 +++++- 1 file changed, 5 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 435c6345c..1cbb1fd7a 100644 --- a/drivers/net/memif/rte_eth_memif.c +++ b/drivers/net/memif/rte_eth_memif.c @@ -405,7 +405,11 @@ eth_memif_rx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts) refill: if (type == MEMIF_RING_M2S) { - head = __atomic_load_n(&ring->head, __ATOMIC_ACQUIRE); + /* ring->head is updated by the receiver and this function + * is called in the context of receiver thread. The loads in + * the receiver do not need to synchronize with its own stores. + */ + head = __atomic_load_n(&ring->head, __ATOMIC_RELAXED); n_slots = ring_size - head + mq->last_tail; while (n_slots--) {