From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by dpdk.org (Postfix) with ESMTP id 97B0D1B476 for ; Fri, 13 Jul 2018 10:29:49 +0200 (CEST) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 13 Jul 2018 01:29:47 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,347,1526367600"; d="scan'208";a="72422380" Received: from dhunt5-mobl2.ger.corp.intel.com (HELO [10.237.221.75]) ([10.237.221.75]) by orsmga001.jf.intel.com with ESMTP; 13 Jul 2018 01:29:46 -0700 To: Thomas Monjalon Cc: dev@dpdk.org, jerin.jacob@caviumnetworks.com, hemant.agrawal@nxp.com, arybchenko@solarflare.com, ferruh.yigit@intel.com, bruce.richardson@intel.com References: <20180621132414.39047-2-david.hunt@intel.com> <20180626092317.11031-1-david.hunt@intel.com> <2730584.abn78hPeQH@xps> From: "Hunt, David" Message-ID: Date: Fri, 13 Jul 2018 09:31:38 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <2730584.abn78hPeQH@xps> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Subject: Re: [dpdk-dev] [0/9] examples/vm_power: 100% Busy Polling 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: Fri, 13 Jul 2018 08:29:50 -0000 Hi Thomas, On 12/7/2018 8:09 PM, Thomas Monjalon wrote: > 26/06/2018 11:23, David Hunt: >> This patch set adds the capability to do out-of-band power >> monitoring on a system. It uses a thread to monitor the branch >> counters in the targeted cores, and calculates the branch ratio >> if the running code. >> >> If the branch ratop is low (0.01), then >> the code is most likely running in a tight poll loop and doing >> nothing, i.e. receiving no packets. In this case we scale down >> the frequency of that core. >> >> If the branch ratio is higher (>0.01), then it is likely that >> the code is receiving and processing packets. In this case, we >> scale up the frequency of that core. >> >> The cpu counters are read via /dev/cpu/x/msr, so requires the >> msr kernel module to be loaded. Because this method is used, >> the patch set is implemented with one file for x86 systems, and >> another for non-x86 systems, with conditional compilation in >> the Makefile. The non-x86 functions are stubs, and do not >> currently implement any functionality. >> >> The vm_power_manager app has been modified to take a new parameter >> --core-list or -l >> which takes a list of cores in a comma-separated list format, >> e.g. 1,3,5-7,9, which resolvest to a core list of 1,3,5,6,7,9 >> These cores will then be enabled for oob monitoring. When the >> OOB monitoring thread starts, it reads the branch hits/miss >> counters of each monitored core, and scales up/down accordingly. > It looks to be a feature which could be integrated in DPDK libs. > Why choosing to implement it fully in an example? I needed to set up a thread that looped tightly (~100uS interval) and run it on it's own core. From what I have seen in other cases, it is usually the application that allocates cores and decides what to run on them. I did think about putting some of it in a library, but for this case I thought it made more sense to keep it purely as a sample app. Regards, Dave.