From patchwork Mon Sep 21 19:22:51 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Honnappa Nagarahalli X-Patchwork-Id: 313401 Delivered-To: patch@linaro.org Received: by 2002:a92:5ad1:0:0:0:0:0 with SMTP id b78csp3821870ilg; Mon, 21 Sep 2020 12:23:14 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyXSNkXXKD+crWgOmn1dzrDmD/VJ0hA7KvbgQqBGCPY0LRWfWKyVxNeJ1FaraDX0T9mArCm X-Received: by 2002:a17:906:b74c:: with SMTP id fx12mr956176ejb.547.1600716194240; Mon, 21 Sep 2020 12:23:14 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1600716194; cv=none; d=google.com; s=arc-20160816; b=pzaVj7BWgfeuuLBjt10+tFa1Q+/xyMKUUQMZny7Vu0rJjbpWybFQaHRteJ4XTVFs7Z HQwH07BvODos6n8ZKLyc8P85mV9xxn4rv/fvVZrSIciGPVwJfNLvs7FJEFomfaOEsKxq thT46fdRs5o/yeN7hCdMQuGdjX+I5pCeBAfz6A1cpBCl6gNuzlwLEIBbAMXweYCtyXkN jw2p1+ch/dymIl+ykllIZmc2bFJ3jhuO2MBTP7b9/L1OXj7COM03GZsfmf1pNOT1FHrn 4boKVjTscpKLCz2RFNUlOi8XW/w6jh7fGdWQTBJLEXhNnq52ERQn9h4WWJDkV1m2tvG+ XB+w== 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:message-id:date:cc:to :from; bh=4TdyMiDDBwsxoyHgJvqPVUlFBkgvgir3Cxdbq/mjJm8=; b=EAFiGY7AoIUqpNQ4C4tOsNPX3UAEtYNoEcUzuB0tV2oJtRs+xPcF6pVtMqwpO7MwMv V9Z79QXgPjW9qzMFtkBNVYsBkCcD+AHht+xxW7iuLH8BvDI56386RZ3gXzqju8qKtEpY 8mGP4S9WVf+rgexsIvon1d4lU7WeNPN/k37VvwMN+aK/2BKuJ+PB4uszq3cbLc0h3Qay kvwPav9giHLPYc1z/ER/iwCovvmn9vOT895uC2EtGw+Bpt0sL5gbdCnqRWGLWqZ32aPW YrD+zPogQ2aaDH4qpKcRPgTq/2EGG6cEIGJ9c1+hMEIPT5eA8oaZuodsqMF5ofJ3Gx62 q/UA== 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 i88si9723479edd.601.2020.09.21.12.23.14; Mon, 21 Sep 2020 12:23:14 -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 484D31D977; Mon, 21 Sep 2020 21:23:13 +0200 (CEST) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by dpdk.org (Postfix) with ESMTP id 7B3B21D94B; Mon, 21 Sep 2020 21:23:11 +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 BD5411045; Mon, 21 Sep 2020 12:23:09 -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 AC1E43F718; Mon, 21 Sep 2020 12:23:09 -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 14:22:51 -0500 Message-Id: <20200921192254.20560-1-honnappa.nagarahalli@arm.com> X-Mailer: git-send-email 2.17.1 Subject: [dpdk-dev] [PATCH 1/4] net/memif: do not update local copy of tail in tx function 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" In the case of S2M queues, the receiver synchronizes with the sender (i.e. informs of the packets it has received) using ring->tail. Hence, the sender does not need to update last_tail. In the case of M2S queues, the receiver uses last_tail to keep track of the descriptors it has received. The sender is not required to update the last_tail. Updating the last_tail makes it a shared variable between the transmitter and receiver affecting the performance. Fixes: 09c7e63a71f9 ("net/memif: introduce memory interface PMD") Cc: jgrajcia@cisco.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, 2 insertions(+), 4 deletions(-) -- 2.17.1 diff --git a/drivers/net/memif/rte_eth_memif.c b/drivers/net/memif/rte_eth_memif.c index c1c7e9f8d..fd7dbc53e 100644 --- a/drivers/net/memif/rte_eth_memif.c +++ b/drivers/net/memif/rte_eth_memif.c @@ -568,12 +568,10 @@ eth_memif_tx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts) ring_size = 1 << mq->log2_ring_size; mask = ring_size - 1; - n_free = __atomic_load_n(&ring->tail, __ATOMIC_ACQUIRE) - mq->last_tail; - mq->last_tail += n_free; - if (type == MEMIF_RING_S2M) { slot = __atomic_load_n(&ring->head, __ATOMIC_ACQUIRE); - n_free = ring_size - slot + mq->last_tail; + n_free = ring_size - slot + + __atomic_load_n(&ring->tail, __ATOMIC_ACQUIRE); } else { slot = __atomic_load_n(&ring->tail, __ATOMIC_ACQUIRE); n_free = __atomic_load_n(&ring->head, __ATOMIC_ACQUIRE) - slot;