site_archiver@lists.apple.com Delivered-To: darwin-dev@lists.apple.com On Jun 21, 2008, at 7:06 AM, Jean-luc Chasseriau wrote: Thanks all for these information! I would like to quickly give some feedbacks from your help. That is correct. These values are maxima. No. = Mike _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.appl... 1) sysctl doesn't seem to provide the _current_ cpu frequency since *cpu* values don't change while time is passing by. 3.c) why retrieving this value? The main goal is quite stupide but the background (how to) is still interesting to know. I would like to make a simple widget which is displaying cpus frequencies on the menu bar. (I saw that on linux + gnome, very useless I agree, but fun! :)) Not only useless, but inaccurate. You might as well generate random numbers and display them. That is one of the reasons the information is not made available; see below. Michael, could you give me an entry point to help me where can I start to look to gather this? The Darwin kernel uses core P-states very aggressively on many platforms. The very act of running code to examine the current P- state and draw something based on that value will change it. It is not uncommon to see over 100 P-state transitions per second on a given core. Likewise, C-state transitions are very common (tens to hundreds per second, depending on workload). The details of the code that manages these states (not the policy) can be found in the published Darwin sources, but all this will tell you is that the system is P/C-state agile on a core by core basis, and that these states are intimately tied to the work state of individual cores. There is no user-relevant concept of "current P/C state" for a given core. This email sent to site_archiver@lists.apple.com