From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.mhcomputing.net (master.mhcomputing.net [74.208.228.170]) by dpdk.org (Postfix) with ESMTP id CF8F75A9B for ; Thu, 14 Jan 2016 08:03:56 +0100 (CET) Received: by mail.mhcomputing.net (Postfix, from userid 1000) id 092FC214; Thu, 14 Jan 2016 02:03:55 -0500 (EST) Date: Thu, 14 Jan 2016 02:03:55 -0500 From: Matthew Hall To: "Zhang, Helin" Message-ID: <20160114070355.GA14958@mhcomputing.net> References: <20151206000839.GA23450@mhcomputing.net> <5688D2EE.5010700@mhcomputing.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Cc: "dev@dpdk.org" Subject: Re: [dpdk-dev] librte_power w/ intel_pstate cpufreq governor X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 14 Jan 2016 07:03:57 -0000 On Tue, Jan 12, 2016 at 03:17:21PM +0000, Zhang, Helin wrote: > Hi Matthew > > Yes, you have indicated out the key, the power management module has changed or upgraded. > Could you help to try the legacy one to see if it still works, as indicated in your link? I can do this, but according to the documents I am reading, the old Power Management module is secretly stubbed out / no-opped inside of the Skylake CPU core, and the core manages its own clockrate internally every 1 msec instead of every 30 msec with input from the OS (Intel Speed Shift technology). If this is true, then I suspect there is no point to getting it to work again with either the old frequency driver or the new driver, because the chip would not listen to it. So then it seems like it makes sense to skip the clock adjustment callbacks on Skylake and take extra stuff out of the fastpath code. > Taking control of the governor from kernel to user space, might need one > more checks before that. But it is actually not a big issue, as user can > switch it back to anything via 'echo'. I think it's a bit bigger issue, as it leaves the chip in full-power mode without really warning anybody, instead of the standard default adaptive mode. > Yes, it seems that librte_power is out of date for a while. It is not easy > to track all the kernel versions. Now we have good chance to do that, as you > have reported issues. Let's have a look on the new power management > mechanism and then see if we can do something. Yes, let me know how I could help. I don't know very much yet. My machine is Skylake Core i7-6700k. Unfortunately I think I am in trouble here, because there is no whitepaper on the Intel website for Intel Speed Shift technology at all. > Really thanks to your questions! I am looking forward to getting some answers figured out together. > Regards, > Helin Matthew.