> -----Original Message----- > From: Matthew Hall [mailto:mhall at mhcomputing.net] > Sent: Thursday, January 14, 2016 3:04 PM > To: Zhang, Helin > Cc: dev at dpdk.org; Liang, Cunming; Zhou, Danny > Subject: Re: [dpdk-dev] librte_power w/ intel_pstate cpufreq governor > > 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. That's disappointing if Skylake is like that. Let's have a learning first, and then check if we can fix that. But in addition, DPDK provide interrupt based packet receiving mechanism, can it be one of your choice?
For now, I am afraid that I don't have time on it, as we are all focusing on the next release development. If no objection, I will find time later (may be in a month) to investigate that. Of cause, please try to investigate that from your side. > > > 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. That's always there, for example, DPDK can exit accidently, without caring anything. Then you can have the similar issue again. > > > Yes, it seems that librte_power is out of date for a while.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. It seems that you are so important for Intel. :) I don't have Skylake in hand. :( Anyway, I will try to find time on that, and hopefully will find something or solution. Thank you very much for the great jobs! Regards, Helin > > > Really thanks to your questions! > > I am looking forward to getting some answers figured out together. > > > Regards, > > Helin > > Matthew.
