From patchwork Mon Sep 21 19:22:53 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Honnappa Nagarahalli X-Patchwork-Id: 313403 Delivered-To: patch@linaro.org Received: by 2002:a92:5ad1:0:0:0:0:0 with SMTP id b78csp3822057ilg; Mon, 21 Sep 2020 12:23:29 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxZtG2S+1cEuhwBG5YywBd7Wc3Ew4xpyNfvVAwQL5q35pAUIPHaZxF/YgNUULnibsUcZuvi X-Received: by 2002:a05:6402:3105:: with SMTP id dc5mr447574edb.105.1600716209627; Mon, 21 Sep 2020 12:23:29 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1600716209; cv=none; d=google.com; s=arc-20160816; b=OOtCV+MkZ0hiJkzqZIfEk7td+HcO92z9rEFGwf/Xe8rZEj3nYQ1+NJDLrip1rFoNj9 QwfFU5T2z4UPPQg4B2nMOSY7r2M6XiFE3xho3ezbeUNYP8tiDmujP4jbThK9cs7zyKmq e138YLE4eDPL4K+AY4Nrb6twtSH2Aopzi7WTABuhwz+fyqfbQMEuvJN7+gL01Qnxci7R K5+FIfb4WjZ99rIYz3pvVGWko/aEMIfQjGxM0oscoZEPnM8545PlbETU2zCi2uxfTFLD OjeLvDUaTZQdCxSYge4pHC79XApxXRv3uIF3UTU0By9XdCJDk0AJi3PEUpE/SkpA3oLx LN7Q== 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=t1ySOYB4skjTE0Zv4MJt5hCqmd5l2SyuddKHXDW7zKE=; b=vj/5h4xwqvebFrEifscupXBg9XieJOpHjhqY2NK+9Y1OEoEjNgnyIpVa924f1FTOTS gwGCFiEMOB3K6IudkzxnGEC1svYTlhTXxQZvotTwmw7KBtCTPtQS6k+mOhN0MriNlO5C 9hhZ0qBQwSQ/FGjSmz8xbMXp4y0apN4Fp4Gxf1TLNalXKsjtnNTSYOuDFXMJ9SKqm132 kr1OdVoTHOp20soqWji7JwCr/Jv+hteCNoUFTqOQyLz47M3YxRBZeIfb+tmbzldOXxtR 8bZOF+6juucXuhi5MmwnkvpQmvB8WBkz8aibKxlaMj465aswSXFoG2pbCNBwQ8uaElOj xqVA== 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 a3si4025503edn.245.2020.09.21.12.23.29; Mon, 21 Sep 2020 12:23:29 -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 B01F51DA64; Mon, 21 Sep 2020 21:23:17 +0200 (CEST) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by dpdk.org (Postfix) with ESMTP id 5F0891D993; Mon, 21 Sep 2020 21:23:13 +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 E085214F6; Mon, 21 Sep 2020 12:23:12 -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 D07663F718; Mon, 21 Sep 2020 12:23:12 -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 14:22:53 -0500 Message-Id: <20200921192254.20560-3-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 3/4] net/memif: relax the load of ring head pointer for S2M 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 S2M rings, ring->head 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 0d064c8fa..435c6345c 100644 --- a/drivers/net/memif/rte_eth_memif.c +++ b/drivers/net/memif/rte_eth_memif.c @@ -569,7 +569,13 @@ eth_memif_tx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts) mask = ring_size - 1; if (type == MEMIF_RING_S2M) { - slot = __atomic_load_n(&ring->head, __ATOMIC_ACQUIRE); + /* For S2M queues ring->head 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->head, __ATOMIC_RELAXED); n_free = ring_size - slot + __atomic_load_n(&ring->tail, __ATOMIC_ACQUIRE); } else {