From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f178.google.com (mail-wr0-f178.google.com [209.85.128.178]) by dpdk.org (Postfix) with ESMTP id 485547CEA for ; Tue, 16 Jan 2018 14:13:32 +0100 (CET) Received: by mail-wr0-f178.google.com with SMTP id 100so15097597wrb.7 for ; Tue, 16 Jan 2018 05:13:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=6wind-com.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=iMdFyQQ6XT9wnSatdVUsD5bRvJZAUStk4q0Xl/SIQZU=; b=ISXeq2I2mqWjscnglsd66xJzBeJDaIq0bVVqusspXwdVmwe/XKoGkNxC47myyeutVo Bpv2SOlVwrMqXLlKPoq0IvIVj4YjaiG0RgupcrhjfkON1fKZZaFIIOA5wj1JfR1d4vhm /HCUeWAkMH/7tJEzTWZjY/aiM0LwAy8zJ/B9/YnddG/moO+UetytKRdGy/HjlSHb7fVd Zs9W1KWIkQwuuBCOpp5BJ0/vuJJG+CySBFAmCelnZwfqq0AX7ZZkcnB5yKumcLWVOtJE YjC4r7Y6HXA+5S+zc6WjLmc7p2WuRQyBGnCtRxaIUSCtzFDaeeklT7rFCY7AUIa0rSf1 uoxw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=iMdFyQQ6XT9wnSatdVUsD5bRvJZAUStk4q0Xl/SIQZU=; b=YvJIrxxyjyveXvnkiXL19oOfmhNnDcj5U2dnFzgoa1bulv+rLxtGIzI0znx/NXkZPP SRvM9nL7VGZLRUcb5FeiH/NcrphdXufEihL1BDEOEi4jtgH1FQMq8Tn5Y+OKEhObn5LW Qj2QhARLVMFwP0Ux1cbecpr90KTRXbweLDHAHVbHXjMeT5hQSuYr224uGDMxc4GWf8CA dpW+eD+vtMXmpkl8sw+xyIQN9oXHf+cIuDP0Zy/QMQ85ljrkIBihPoPhcTtp0IFVyJ7b 18tIF2WQZ74I76O91Y83a47zGtDSMrGgxDP1t51FsEplmmCkzw94rncVLGKZpSRPVwNv 9rUQ== X-Gm-Message-State: AKwxytcr6mDv6aVuwTJoLTljJR1id5o9zF11c33nkHgckPLxvDRLuwa4 AoBiYU0Sfv5+R9mFYL7jW9HW7KUU X-Google-Smtp-Source: ACJfBosgwIo2VS34/iX9AAN01h0uYjNQuwgVrGGYiDGf/JHBeP0B3dd1SjkArrHSHVopkvlKxobN0g== X-Received: by 10.223.189.15 with SMTP id j15mr11704613wrh.1.1516108411930; Tue, 16 Jan 2018 05:13:31 -0800 (PST) Received: from 6wind.com (host.78.145.23.62.rev.coltfrance.com. [62.23.145.78]) by smtp.gmail.com with ESMTPSA id n62sm1863007wma.40.2018.01.16.05.13.31 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 16 Jan 2018 05:13:31 -0800 (PST) Date: Tue, 16 Jan 2018 14:13:19 +0100 From: Adrien Mazarguil To: Kevin Laatz Cc: dev@dpdk.org Message-ID: <20180116131319.GF4256@6wind.com> References: <20180112103053.47110-1-kevin.laatz@intel.com> <20180112104846.47396-1-kevin.laatz@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180112104846.47396-1-kevin.laatz@intel.com> Subject: Re: [dpdk-dev] [PATCH v2 0/3] Increase default RX/TX ring sizes 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: , X-List-Received-Date: Tue, 16 Jan 2018 13:13:32 -0000 Hi Kevin, On Fri, Jan 12, 2018 at 10:48:43AM +0000, Kevin Laatz wrote: > Increasing the RX/TX default ring size to 1024/1024 to accommodate for > faster NICs. With the increase of number of PPS, a larger RX buffer is > required in order to avoid packet loss. While a ring size of 128 may be > large enough for 1G and possibly 10G NICs, this is not going to scale to > small packet sizes at 25G and 40G line rates. As we are increasing the RX > buffer size to 1024, we also need to increase the TX buffer size to ensure > that the TX side does not become the bottleneck. > > v2 > - fixed typos in commit messages > - fixed typo in Cc email address I agree with the above and this series contents but would like to comment anyway. Since typical TX/RX bursts are usually somewhere between 16 to 64 packets depending on the application, increasing ring size instead of burst size to keep up with packet rate may mean that software (PMD/application) is too slow on the RX side or hardware is too slow on the TX side (rings always full basically), and this is worked around by introducing latency to absorb packet loss. This is not necessarily a good trade-off. Granted the most appropriate burst/ring/threshold values always depend on the application and underlying hardware, and each vendor is responsible for documenting ideal values for typical applications by providing performance results. My concern is that modifying defaults makes performance comparison with past DPDK releases more difficult for existing automated tests that do not provide ring size and other parameters. There should an impact given that larger rings require more buffers, use more cache, and access more memory in general. -- Adrien Mazarguil 6WIND