From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f42.google.com (mail-wm0-f42.google.com [74.125.82.42]) by dpdk.org (Postfix) with ESMTP id EF7BC1B2F7; Sun, 22 Oct 2017 11:46:57 +0200 (CEST) Received: by mail-wm0-f42.google.com with SMTP id q124so4538927wmb.0; Sun, 22 Oct 2017 02:46:57 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=Rvv4jicMFzQLu0XUFcEvpVISmVhdS0Hv4YtVzyYwcYA=; b=Dqnf4+ydxBfHADJHfbCw5w/JzYnwWxRqaJ46VkDdkcNLpb5V9PBKTyO6wTRf+Yq297 /Vl5R7QmUSKEe4uQ1OmFgDVSIe0/pk/L/mUKVxo6MFYHdzgUI/fA4WZuqVukU7q9vncZ D2do6z6YFq635QqkktANH6N96KEY8WuxveHulxTQQx+8GPECnaxMg7qRn5p+wbR5g9JL CASIgsM6qffBajrBs+FqLj5yLJiHw7lU+Jt3KmiunsGxO69LKz7UlY77iaxK84l8N/I8 JtI/KwVt2+g9NYfHa/nhAUabH1Sp3ZWOw+6zgzp/e3UAhQTQ9uCUfsxbZCSRQYJZxj7y 2Wsw== X-Gm-Message-State: AMCzsaXNK5k1TiJw29TtxPrNIK9N7B/JKZhLv+UyTaUDiFioWOyACZtG kj+KCFWDwj8wduZ0PyN9BHc= X-Google-Smtp-Source: ABhQp+RaE9VcAfEzP2q9yZ2O6TONtRPSiQD6RxJ8AUsz3g2kZ2UxwlGMH7OeO4K00NpvPGxIdZGK4w== X-Received: by 10.28.60.8 with SMTP id j8mr2315636wma.92.1508665617715; Sun, 22 Oct 2017 02:46:57 -0700 (PDT) Received: from [192.168.64.169] (bzq-82-81-101-184.red.bezeqint.net. [82.81.101.184]) by smtp.gmail.com with ESMTPSA id m198sm1228479wmg.20.2017.10.22.02.46.55 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 22 Oct 2017 02:46:56 -0700 (PDT) To: Yongseok Koh , adrien.mazarguil@6wind.com, nelio.laranjeiro@6wind.com Cc: dev@dpdk.org, stable@dpdk.org, Alexander Solganik References: <20171022080022.13528-1-yskoh@mellanox.com> From: Sagi Grimberg Message-ID: Date: Sun, 22 Oct 2017 12:46:53 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: <20171022080022.13528-1-yskoh@mellanox.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-stable] [dpdk-dev] [PATCH] net/mlx5: fix Tx doorbell memory barrier X-BeenThere: stable@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches for DPDK stable branches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 22 Oct 2017 09:46:58 -0000 > Configuring UAR as IO-mapped makes maximum throughput decline by noticeable > amount. If UAR is configured as write-combining register, a write memory > barrier is needed on ringing a doorbell. rte_wmb() is mostly effective when > the size of a burst is comparatively small. Personally I don't think that the flag is really a good interface choice. But also I'm not convinced that its dependent on the burst size. What guarantees that even for larger bursts the mmio write was flushed? it comes after a set of writes that were flushed prior to the db update and its not guaranteed that the application will immediately have more data to trigger this writes to flush.