From patchwork Mon Sep 28 19:03:28 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Honnappa Nagarahalli X-Patchwork-Id: 313679 Delivered-To: patch@linaro.org Received: by 2002:a92:5ad1:0:0:0:0:0 with SMTP id b78csp3545401ilg; Mon, 28 Sep 2020 12:04:37 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzKOPzMZIMEkl7qCLIIQz10WKIOBTLBN0PGNeiByLsUsuvK0Z9EnQRwFAXTdkgF7iXD44J9 X-Received: by 2002:a17:906:c309:: with SMTP id s9mr219877ejz.167.1601319877525; Mon, 28 Sep 2020 12:04:37 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1601319877; cv=none; d=google.com; s=arc-20160816; b=j7IZMwF1oNtJOhJRnnTWvPaMphis9RnAJRrhCmwykbtvoBNvLSmWr4coWbTlHBy0ff U6zbZXGITDy6hcGdVPuec1gS4F+KaiuFJeieGZB/cH4lNDolfgriRVDNsEkSmCI+RBIn i3PbdVucoa/PGcwnKmnAVZilVTdMqDDwGHcZp/XxsvtjIv7Ti4GU7PZXAzKX5uRYhpph yFZ2K6lWaaAHxLpnSasjKJSttFd+NS69vQERCFzyRf1Uzs+Xs4B8vFfyaU69ulTLMdQV 08LOro84bc0knE+BKi/Mwy8/BHBQ8BQWYKe7HlgknMrslUltdXrAITLboL7tApBw8uYI d+5w== 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=klz5Tr4Y+lTVKXVxaokPVFGxjaVucOvYhhlWDXoJaGQ=; b=GDiEFvXPiqdv7GFHpB/JdGUT3sNQnMNR4u8sXp+Jb4/57umzpPIJFXOnEaESRRaeUz 3GTVBj7Q6fZZbXE40HV9GwQwv38mufLKPygd7bMNejOeNNYB+i7UpyHQ97Sc+yoSkpGl latatevWW7RI7HZDbYdmB+u2B1UhL1bNaElz5WP2AF4kC92uPUWh9c7OB1Y93wvMGO7o Q0+eaG1uXfIX7MF7Sm+nTt0Y7qvDfQ5I2YYBHB7c3DlyWhZuiOTYhnK6cOtNRGEvCVWo I7SohiRSYbaAF1FXWj1M3w8tP6ibym81M1egA83m5rOocudgZfY95rX/CxTlY4KjqNSa TyVg== 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 da1si1250614edb.102.2020.09.28.12.04.37; Mon, 28 Sep 2020 12:04:37 -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 80FFD1D69D; Mon, 28 Sep 2020 21:04:10 +0200 (CEST) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by dpdk.org (Postfix) with ESMTP id EBA1A1D66B; Mon, 28 Sep 2020 21:04:06 +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 45D51113E; Mon, 28 Sep 2020 12:04:05 -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 355963F70D; 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 14:03:28 -0500 Message-Id: <20200928190334.40624-2-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 2/8] 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 Reviewed-by: Ruifeng Wang --- 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 130099f2e..8bacacaa8 100644 --- a/drivers/net/memif/rte_eth_memif.c +++ b/drivers/net/memif/rte_eth_memif.c @@ -585,7 +585,13 @@ 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; }