On other processors and other designs, threads can provide most of what a core can provide. On some processor architectures and some designs, threads are little better than a mechanism for a faster process context switch and a scheduler optimization. How much less varies by the details of the processor. Multi-threading provides less than what a core provides, or a "thread" would be called a "core". So an 4 core i7 can look like 8 CPUs.īobHarris is aware of the following, but here are some added details. The CPU chip has multiple cores (each core acting as a central processing unit (CPU)), and in the i7 line each core can use HyperThreading to behave as if it is really 2 CPUs. I'm sure there can be others, and except for maybe the power saving aspect, I cannot think of any strong reason for personal computer to disable any CPUs on a chip. In a NUMA (Non-uniform memory access) computer environment, you may want to use affinity to keep a set of processes running on a specific section of the NUMA systems, as the non-uniform memory means a programming sitting in RAM may not be close to some CPU access speed wise, so you try to avoid letting the process schedule on one of those CPUs.In the good old days, before chip based CPUs where the CPU was on 1 or more logic boards, a CPU may fail, and the user could limp along on 1 CPU by shutting down the broken CPU until the service tech could show up, or the customer could take the system offline and not hurt their business.But the VM software is using all the CPUs the box has to offer. This is a weak argument, as today, most cloud vendors just use virtual machines, and assign as many virtual CPUs to the VM as the customer wasn't to pay for. In a cloud environment the cloud vendor may offer different pricing models, and if the customer does not what to pay too much, the cloud vendor may turn off CPUs.The chip itself will often times power down (or low power) circuits that are not in use. You should also use Macs Fan Control from if you want to be able to use your 2.4 kilobuck laptop on your lap without being extremely uncomfortable from the excessive heat. "Reduce Transparency"), "Differentiate without color".Īlso, go to System Settings, Dock, and select "Minimize windows using:" "Scale effect" (instead of "Genie effect"). Go to System Preferences, Accessibility, Display, and turn on all the options to "Reduce motion", "Increase contrast" (incl. You can use Intel Power Gadget from Intel to monitor actual CPU frequency and verify that it doesn't go above the spec, e.g., on MacBook Pro 16" 2019 w/ a 6-core i7-9750H, doesn't go above the regular 2.6GHz up to 4.5GHz Turbo. Verifying that Turbo Boost got disabled. It would seem that the Turbo Boost Switcher from can be made to work on macOS Catalina 10.15 after some troubleshooting, but it's kind of buggy, and the free version keeps requiring you to enter a password each time upon a wakeup. Turbo Boost is most definitely the most power-hungry and useless technology that cannot be easily disabled on a Mac. It appears possible to use Apple's cpuctl to take some of the CPUs offline it looks like an internal tool supplied by Apple there's no easy way to know which CPUs are hyperthreading ones (I think they're supposed to be the even ones), so, a safe bet may be to disable half of the upper even-numbered CPUs, to effectively disable 1/2 of Hyper-Threading, e.g., on a 6-core machine with 12 virtual CPUs, we can disable 3 of them rather safely: sudo cpuctl offline 7 9 11 sudo cpuctl listĬan also use the CPUSetter from which has a setting dedicated to specifically disabling Hyper Threading which results in all even-numbered CPUs being taken offline. Some of the useful tools / notes for reigning in macOS Catalina 10.15 running on MacBook Pro 16" 2019 monstrosity:
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