Process hopping occurs "involuntarily" too, as a side effect how the OS scheduler tries to juggle and spread load. I'm not sure if the hardware can override what the OS says. That could be possible only if the CPU as a hardware swaps the CPU core order in the hardware layer. Otherwise the OS's process scheduler is the one which determines what processes + threads run on which core. Actually anchoring a process to a specific core needs extra effort, under Linux it was done a decade+ ago with the CPU affinity patch, now I think it maybe part of the core kernel. Plus on Linux you can choose scheduler, you can decide if you want more UI responsiveness or you prefer background tasks. This could be nice presentation topic. But, if you choose Apple... you don't have that much influence on the system. 3.6 GHz vs 3.9GHz turbo freq difference is sure 10% but the disk I/O gain should compensate that IMHO, usually that's a bigger bottleneck. Unless you are doing a lot of computation which doesn't require I/O. Your choice sounds better with the higher I/O.
On Sat, Apr 16, 2016 at 10:51 AM, Curt Lundgren <[email protected]> wrote: > I have a feeling the reason the 3.3 GHz unit is so much faster than the > 3.2 GHz unit relates to 'turbo mode.' If the process you're running is > single threaded, the CPU will kick into high gear and run faster. I > noticed on a secure copy the four cores were doing about the same amount of > work. My theory is the scheduler hops the task from one core to another to > keep a single core from running hotter than the others. The 3.2 GHz unit > will overclock to 3.6 GHz, but the 3.3 GHz unit overclocks to 3.9 GHz. I > believe that's what is responsible for the substantial difference in > performance. > > On Fri, Apr 15, 2016 at 10:32 PM, Curt Lundgren <[email protected]> > wrote: > >> My boss Chris picked up a Retina 27" iMac for my use last year. The 5k >> display is awesome, particularly when rendering small size italic text. >> Deep color doesn't hurt either, and the best part for me is the ability to >> have an xterm open with 120 rows of text that aren't too small to read. >> I've had a 27" iMac at home with the 'standard' 2560x1440 display at home, >> beautiful display. Yet, look at that small text, looks blocky… >> >> One of the best features on the work computer is the Fusion drive. It's >> a combination of a standard SATA drive and a fast SSD on the PCIe bus. >> Apple's CoreStorage presents the pair to the operating system as a single >> volume. It automagically migrates the most often used files to the faster >> storage. Bootup is fast, application loading is fast, and so on. I use >> Microsoft Word for Mac as an example of bloatware - it loads and is ready >> for use in under a second. >> >> Well, who wouldn't want such a machine? It runs Unix, is very >> Linux-friendly - and every once in a while it's fun to watch a 4K YouTube >> video just to enjoy the display. I spend hours mangling Perl code at the >> computer and generally approve of its features. Save your pennies, get the >> computer. I ordered a 3.2 GHz Core i5 unit with the same 1 TB Fusion >> drive. It arrives, I set it up, looks fantastic; I bring it home. Lucky >> thing I looked at System Information. After the initial shock, some >> research. It seems that around August Apple chose to reduce the size of >> the SSD from 120 GB to 23-1/2 GB. Without telling anyone, let's cut the >> capacity by more than a factor of five. Something stinks here, and the >> smell is coming from Cupertino. >> >> After a few discussion with Apple I picked up the 3.3 GHz model with the >> 2 TB Fusion drive - this one actually has the 120 GB SSD. Meanwhile, some >> performance metrics… >> >> I thought there would be no observable difference between a 3.2 GHz >> computer and a 3.3 GHz computer. Indeed there are. Since I'd invested a >> full day in setting things up on the 3.2 GHz unit, I used Super Duper to >> copy an image of the OS onto a 2 TB drive, using USB 3.0. Very impressive >> performance - 105 MB/sec sustained performance. >> >> The 3.3 GHz unit comes home, now the imaging is set up in the other >> direction. Wow, it sustains 150 MB/sec transfer speed going onto the >> system disk. I am impressed! I had been doing SCP file transfers from the >> older 2.7 GHz iMac. With the 3.2 GHz iMac the speed was about 90 MB/sec - >> and that's doing encryption/decryption on the files of course. I did the >> same transfers with the 3.3 GHz unit, seeing some sustained 103 MB/sec >> transfers. I've never seen SCP run this fast. >> >> The swap of the 3.2 GHz unit for the faster one with the 'real' Fusion >> drive coat $175, more or less - well worth it. But if you like Macs and >> think the 1 TB Fusion drive is a good idea, you may wish to reconsider. >> >> Curt >> > > -- > -- > You received this message because you are subscribed to the Google Groups > "NLUG" group. > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group at > http://groups.google.com/group/nlug-talk?hl=en > > --- > You received this message because you are subscribed to the Google Groups > "NLUG" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/d/optout. > -- -- You received this message because you are subscribed to the Google Groups "NLUG" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/nlug-talk?hl=en --- You received this message because you are subscribed to the Google Groups "NLUG" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
