From patchwork Mon Sep 28 19:03:30 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Honnappa Nagarahalli X-Patchwork-Id: 313681 Delivered-To: patch@linaro.org Received: by 2002:a92:5ad1:0:0:0:0:0 with SMTP id b78csp3545910ilg; Mon, 28 Sep 2020 12:05:17 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzpqs8wZCiN+ADyQS7JqmpoLfYVaZzIO2Fbbk0cP/QIQHdzmk7eENQqF3y+h0lzEuXtTKcS X-Received: by 2002:a17:906:e103:: with SMTP id gj3mr210883ejb.153.1601319917265; Mon, 28 Sep 2020 12:05:17 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1601319917; cv=none; d=google.com; s=arc-20160816; b=S4fbydzNZ4T/9MTCn5AD3g+DuTGi+D2sn8Mgk5teZ9C4lU+8TdTl1FTRH98u+9Ax/6 /kNBhWu4kV5xCvWQOCX1pAl6OMFZiFH9DArKNpENhJhskT95mldVQhGj+5Q46gMY9D45 geCxlWvrFw8WTbjmI3DjOKAXTzczTiBqZgfE1NTLRB10S687TBtICSk8JTDu3eykZOH8 jf7FmAtzhxj+Jgalt/AbrT7X3WIx+iupaV7aoXEjOx3rVDuZdZ3fz5jgO2zR4bMLLQMN LTGnTM5ZOnyDkyCrHeXlWFm+ZnE1+riYGiFyDf1F7LnAYMDRjbFSIcoQw2fRnMGDsue+ r2Eg== 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=Mz8eWWz+xpBFsQgArznYQwH3zLyx/HWjC9dukxdjtPc=; b=mEyPhc6IC/llJZsMlNMUMFlkKFISQb9gY1JrWRQJOMlfgss5wZdYu7ZARUd06L2u62 JfPrIIV91jDp2JqIm+E0bMDOJ+mruFxyGlPoP06QgkPh2svwIBS5smOewHpm5AtOZP0c aLjHwzLIIt4TU4XFHOc9W5rfa+G2VCLV+nQ0cxiO6UweXjammyVby+i+ml/bM8itlFae qxJ27ZwA0aHndsoOTSAqh0VbS3yQzKKLslAbwmLzJf0I7B+mjjGN3Ek0wvGAk/2XivE/ NvT+ZN42IMbMUhe8JdcLvbx+zfZGL1rjOzTKEerwBVDjH5h5/JJuzk4lFv5fVvM+3W4Y nPXA== 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 l10si1135861edr.220.2020.09.28.12.05.17; Mon, 28 Sep 2020 12:05:17 -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 08D481D6BE; Mon, 28 Sep 2020 21:04:14 +0200 (CEST) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by dpdk.org (Postfix) with ESMTP id F2EEA1D5D8; 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 6E53214BF; 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 5D7F13F70D; Mon, 28 Sep 2020 12:04:06 -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 14:03:30 -0500 Message-Id: <20200928190334.40624-4-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 4/8] 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 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 159b45180..96db76121 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) 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 {