iMac Pro Mac Performance Guid not recommending iMac Pro

Discussion in 'iMac' started by briloronmacrumo, Mar 13, 2018.

  1. filmak, Mar 13, 2018
    Last edited: Mar 13, 2018

    filmak macrumors 65816

    Jun 21, 2012
    between earth and heaven
    Thanks for spotting them. Useful reading.
    Most of his problems seems to be software related.
    Now about hardware, I think that the iMP 's sealed system, is making any occurred problems to seem really worst.
  2. iMacDonald macrumors member


    Oct 27, 2016
    There was already another thread about that article.
    We do not know if that boot problem was isolated to the iMac Pro or was more related to that particular update as I personally experienced something very similar on a normal 2013 iMac. The update was huge and took a while to install on my Macs.

    For people into photography I'm astonished that website looks so poor.
  3. fathergll macrumors 65816

    Sep 3, 2014
    If you want to see issues you should have seen this forum back in 2014 when the Retina iMacs were released. It was either the MacOS GUI for the 2GB memory cards caused stuttering because of poor coding or the 4GB cards got so hot you could fry and egg on them.
  4. joema2 macrumors 68000


    Sep 3, 2013
    Lloyd is very smart and you'll often see deeper insights from him than most other reviewers, and certainly more than a superficial vlogger-style review of the iMac Pro.

    He makes some good points about Apple's numerous quality control issues in recent years. E.g, the dumbed-down Disk Utility which actually had a broken UI in El Capitan -- the cursor turned to a column separator but the columns wouldn't move.

    On the iMac Pro I had a similar "infinite boot loop" problem as what Lloyd mentions. This isn't unique to the iMac Pro and has been periodically reported by other users on various Macs:

    I booted to safe mode, did a few things recommended in the above article and it finally started working. Obviously that should never happen but it's not unique to the iMac Pro.

    Re performance of the iMac Pro vs the top-spec 2017 iMac, I have both of those on my desk, and the iMP is 10-core Vega 64 with 64GB RAM.

    One some workflows the iMP is a lot faster than the top 2017 iMac. On others it's not. Lloyd is correct that it's not always faster, but this isn't necessarily Apple's fault and has little to do with the iMP design. A 10-core Xeon PC might not be any faster either on those workflows.

    The sad truth is performance evaluation is now much more complex and much more limited by application software design. There are a myriad of software "load paths" through the OS and hardware space. One path can be fast and the other slow -- on exactly the same hardware. It depends on how the app software leverages the underlying features. If it uses efficient multithreading, if it properly uses hardware accelerators like Quick Sync, nVidia's NVENC, AMD's VCE and AVX vector instructions, it will be a lot faster on new hardware with those features. If the app software does not properly leverage those, the expensive new hardware won't help much.

    There can even be great variation within the same app. E.g, on a 10-core Vega 64 iMP, FCPX exports to 4k 10-bit HEVC 32x slower than 8-bit HEVC. That is likely because the current software and OS don't support hardware accelerated 10-bit encoding on the Vega 64 VCE logic. You could maybe blame Apple -- from a software standpoint -- but that wasn't Lloyd's point. His point was the iMac Pro hardware. Yet from a hardware standpoint, this isn't Apple's fault. They are constrained because Intel doesn't make a Xeon with Quick Sync.

    In most Lightroom 7.2 tests I've done between the 10-core iMP and top 2007 iMac, LR isn't that much faster. It's about 30% faster on import and 1:1 preview generation but no faster on many other tasks. Like the regular iMac, the iMP often will speed up in LR if you disable LR GPU acceleration. This is a profound coding problem on Adobe's part.

    In Photoshop one of the most powerful (and CPU-intensive) filters is "shake reduction" sharpening. However I don't see any performance improvement on the 10-core iMP vs the top iMac. If Adobe is going to keep writing software like that, you can't fix that with hardware.

    The iMP is a lot quieter than the i7 iMac when under sustained high-CPU load, so that's pretty nice. You don't need a 10-core machine to obtain that -- the base model iMP ($3999 at Micro Center) gives that, which is only a few hundred $ more than the top-spec iMac.
  5. filmak macrumors 65816

    Jun 21, 2012
    between earth and heaven
    Excellent post dear.
    Thank you for taking the time to share these interesting thoughts.
    It's completely true that with Adobe's unoptimised coding you can't have any clear conclusions about performance.
  6. FredT2 macrumors 6502a

    Mar 18, 2009
    On what operations do you find this to be the case? The only things that I have found to be slower with GPU off is using brushes. Unfortunately just about all of the other Develop adjustments suffer when not using GPU. With 7.2 I find that performance using brushes with GPU on is finally pretty good. At least I feel that Adobe is finally making some progress.
  7. joema2 macrumors 68000


    Sep 3, 2013
    I thought it was brushes and several other global adjustments, but it's possible I had clarity brushes painted on all of those. So it's not that painting brushes are slow (like LR used to be) but once painted, and if a certain type of brush, it makes some other things slow, especially changing global sharpening. This is related to whether LR GPU acceleration is enabled.

    You might only see it on high-megapixel raw images; these are 42 megapixel raw still from a Sony A7RII.

    When I tested it a few days ago it took about 3 sec to update a sharpening change if GPU acceleration was enabled on LR 7.2, running on a 10-core Vega 64 iMac Pro. Without GPU acceleration it was sub-second. Now I still see the difference but it's much less -- about 1.8 sec for a global sharpening change using 1:1 previews with GPU enabled to about 1/2 sec with GPU disabled.

    I don't know why the difference. I was on LR 7.2 then and now. There was a macOS incremental update a few days ago -- maybe they optimized some performance cost from the Intel Meltdown or Spectre fixes.

    You are right with GPU off, applying brushes is slow, so it's best to leave it on and just live with periodic slow actions. IN general it seems better than prior LR versions.
  8. Macshroomer macrumors 65816


    Dec 6, 2009
    I definately take in what he has to say but I also have my specific experience and needs and always take that into account once other info considered.

    I am very happy thus far with my 10 core iMac Pro and I am getting a lot of serious work done with it. It’s a relatively new platform and I expect it’s operation to improve as time goes on.
  9. filmak macrumors 65816

    Jun 21, 2012
    between earth and heaven
    I think that Sierra (10.12) is faster and more mature than HS, which has a lot of issues, LR 7.2 + Sierra is a very fast combination in my humble opinion.

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10 March 13, 2018