HI. Great explanation. But can you tell me the hardware difference between a quad core i5 and a quad core i7? Thanks.
-----Original Message----- From: macvisionaries@googlegroups.com [mailto:macvisionaries@googlegroups.com] On Behalf Of Sabahattin Gucukoglu Sent: Wednesday, December 30, 2015 9:27 AM To: 'Chris Blouch' via MacVisionaries <macvisionaries@googlegroups.com> Subject: Re: Best configuration for new mac? Hi Andrew, Let’s start from the beginning. You can think of processor cores as processors in their own right. Each core computes at its clock speed, sharing some resources with the other cores but essentially operating independently. Operating systems of today try to exploit multicore (and, indeed, multiprocessor) systems, by spreading the threads of execution (be they separate independent processes, or separate threads of an individual process) across the cores and/or processors. Using threads of execution that operate in parallel is of course going to produce results faster than merely executing instructions on a single core. The days of merely increasing the clock speed are mostly behind us now, but it was once the norm that operating systems would not really benefit from such parallelism, so that increasing the clock speed was really the only way to go faster. Now, this is all fairly simple, but there is an extra complication. Intel processors have a feature called “Hyperthreading”, which tries to make better use of the processor chip, by virtualising processor cores. These cores are distinct from real processor cores, to operating systems that know the difference. In fact, though, they are really sharing a physical core with another hyperthread. Hyperthreads can improve performance, but they do not run independently; there is contention for the resources on that physical core they share. It is when the contention does not exist that the CPU can exploit parallelism within that core. You can think of it as a sort of “Accelerated computation” for the CPU, in much the way that “Accelerated graphics” is what you get when GPU (graphics) hardware assists the rendering of graphics. What does all this mean? Well, it means that you need to plan your CPU usage carefully, or not, as your requirements dictate. If you want to guarantee a fair balance between host and guest, split up the CPU count. For a quad-core system, let Windows have two cores. You’ll get a known-good balance no matter how hard the operating systems should work their respective processor cores, whether at a standstill or in full flight. On the other hand, you might care less for the performance of your VM; then you reduce the core count, and hope that your operating system will not mind the reduced parallel clock speed. Entirely feasible for Linux, for instance, although I wouldn’t enjoy using Windows above Vista like that for long. And finally, you can go the other extreme: you can give it all to your VM. I do this. It’s much riskier; you had better be sure your OS does not draw more than it really requires, and you can hurt yourself if your host is starved for long periods. But, again for Linux, which is very good at idling the chip when not in use, this is entirely feasible. And about the number of cores available for each VM being higher than the number of physical cores, that’s hyperthreading. VMWare Fusion will do the right thing, balancing your choice of cores evenly between hyperthreaded cores. So actually, a quad-core system has 8 virtual processors, and a balanced system takes 4 virtual cores. A single-core system that could benefit from hyperthreading could easily be given 2 virtual cores without any ill effect. And, yes, if you set the core count to 8, your VM could easily take down the host if it loses control. So, that’s the story. I hope this explains what’s happening, and answers your question. Cheers, Sabahattin -- The following information is important for all members of the Mac Visionaries list. If you have any questions or concerns about the running of this list, or if you feel that a member's post is inappropriate, please contact the owners or moderators directly rather than posting on the list itself. Your Mac Visionaries list moderator is Mark Taylor and your owner is Cara Quinn - you can reach Cara at caraqu...@caraquinn.com The archives for this list can be searched at: http://www.mail-archive.com/macvisionaries@googlegroups.com/ --- You received this message because you are subscribed to the Google Groups "MacVisionaries" group. To unsubscribe from this group and stop receiving emails from it, send an email to macvisionaries+unsubscr...@googlegroups.com. To post to this group, send email to macvisionaries@googlegroups.com. Visit this group at https://groups.google.com/group/macvisionaries. 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