From patchwork Mon Sep 28 19:03:29 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Honnappa Nagarahalli X-Patchwork-Id: 313680 Delivered-To: patch@linaro.org Received: by 2002:a92:5ad1:0:0:0:0:0 with SMTP id b78csp3545620ilg; Mon, 28 Sep 2020 12:04:58 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzK+IHQKPtN4JCDYt/KWkcjirUVCjpNPIvYoQinZrY2lG9myDrbOw8QYFTloI79aahEeb6M X-Received: by 2002:a17:906:4993:: with SMTP id p19mr209903eju.277.1601319897860; Mon, 28 Sep 2020 12:04:57 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1601319897; cv=none; d=google.com; s=arc-20160816; b=w7nME/AILzIs4rqAzSLNJK7n3ReYvQMq8XN71NI0JA7QSJ4feej+cKlYxtOsS7CWAi NIjFKod59QXFYijtKJ4p2OSFG4NcGEfSbpiQwm4HDyQWquEhEYNZSOf8YHAL5Jes2cXX bBK7fLjtTqDwmCL9WRQ6u2olMJIK2qWttoE5xFZnJTKAsfgq9Y5FtP5EH/Y0EbFdRgD0 2OO7DoYON+cothyPrV2w8X7XpJLj5m69Rm7Kl+XDxXyihsy0YVwn3K4qot4UL5KGhWip VUoUHJWhJfcDNh86zhKL9PWjb+PmzqT2b5O6wK2dgFuYJ6X6kMbSoVGl9OTzcnmcEpRP PcFQ== 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=cMFap+loTMjX/P88jnpnAuiWZ2BJzXw2iWl3rYzclbE=; b=RMlKlBF3PG5advJtq278gNiq1q3L2B61w/2dCaihEy54hnwGEHd7Iv5R021SaauyF6 w3ecJ3wLc9Awxk2t7JfGk0utlSJUQ83xFAlYh+L0ZpoJ6McQTVlmcFeO7Ncu3NavZZU1 CWoKkqSZtJRo1ZLqCjuovNx6D2oIiAxQAlIRbWg6WN03zA3eSRaTvmJz2n+KDAeYzeP0 TVJ2pdZahVv91isoxs9VSSzKqYrPhZUPerLSW+B97ubrai5v3h74ThBaLimi1g0SYEqp Jx2ZEAf5akPPlfpMFWcq9ZSC/NqL8c2FxO+D2dF7DUhdvCQ1BmOUnfcqT9tzjeRxrJSW hHuw== 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 p7si1253971edq.28.2020.09.28.12.04.57; Mon, 28 Sep 2020 12:04:57 -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 63DED1D6B7; Mon, 28 Sep 2020 21:04:12 +0200 (CEST) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by dpdk.org (Postfix) with ESMTP id CB3811D681; Mon, 28 Sep 2020 21:04:07 +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 079541477; Mon, 28 Sep 2020 12:04:06 -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 DCDAE3F70D; Mon, 28 Sep 2020 12:04:05 -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, 28 Sep 2020 14:03:29 -0500 Message-Id: <20200928190334.40624-3-honnappa.nagarahalli@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200928190334.40624-1-honnappa.nagarahalli@arm.com> References: <20200921192254.20560-1-honnappa.nagarahalli@arm.com> <20200928190334.40624-1-honnappa.nagarahalli@arm.com> Subject: [dpdk-dev] [PATCH v2 3/8] 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 receiver 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 Reviewed-by: Ruifeng Wang --- 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 8bacacaa8..159b45180 100644 --- a/drivers/net/memif/rte_eth_memif.c +++ b/drivers/net/memif/rte_eth_memif.c @@ -410,7 +410,11 @@ 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--) {