On 5/9/12 10:39 AM, "Dinse, Gregg (NIH/NIEHS) [E]" <[email protected]> wrote:
>On 9 May 2012, at 10:30 AM, Michael_google gmail_Gersten wrote: >>> My Mac Pro has a pair of quad-core CPUs, but both iStat Menus and >>>MenuMeters show a bar chart with 16 bars rather than the expected 8 >>>bars. Is this a Lion thing? There were only 8 bars under Snow >>>Leopard. Why does Lion seem to think I have 16 cores? >> >> You have 8 physical cores, but each core can do two things; it can >> pretend to be 16 cores, 8 physical and 8 logical. >> >> My MacBook Pro will attempt to only use the physical cores normally, >> turning on the logical ones only in very high usage, so I'm guessing >> that they are not as fast as real cores. > >On 9 May 2012, at 10:29 AM, Bruce Carter wrote: >> I believe that is due to HyperThreading. > >Hi Michael and Bruce, >Thanks for the information. Is this new in Lion? I'm sure I only saw 8 >cores displayed in Snow Leopard (and earlier). >Does Lion actually provide a benefit from HyperThreading (and logical >cores), or is performance the same and only displayed differently? The short answer for me is, I don't know. Poking around the web a bit indicates that the hyperthreading doesn't show unless the system is under load, but I have no first hand experience to verify this. -- Bruce Carter, Center for Creative Computing University of Notre Dame, Notre Dame, IN 46556 _______________________________________________ MacOSX-talk mailing list [email protected] http://www.omnigroup.com/mailman/listinfo/macosx-talk
