New Mac Pro hobbled by memory, Tiger?

8-Core Mac Pro Hobbled

Apple's new 8-core Mac Pro may be throttled by its memory technology and its older operating system, according to new benchmarks run on the cutting-edge system. Even though the eight total Xeon cores offer a literal doubling of theoretical CPU performance in testing, testing of memory-intensive programs such as Aperture and Photoshop CS3 -- both of which routinely store gigabytes of images in memory -- reveals almost negligible differences between 8-core and 4-core 3GHz systems.

The seeming deadlock may be attributable to a lack of real-world bandwidth, photographer Lloyd Chambers writes.

"Memory bandwidth is inadequate for 8 cores. It's already a limiting factor with the current quad-core 3.0 GHz Mac Pro," he says. "Memory copy speed is at best 2.9GB/sec on the Mac Pro, in spite of Apple's highly misleading claims of 21.3 GB/sec... That's a measly 700MB/sec per core on a quad-core machine, and only 350MB/sec per core on an octa-core machine. By comparison, a 6-drive hard disk RAID array can easily perform at over 400MB/sec!"

It was unclear whether the bottleneck was completely endemic to Intel's current Xeon 5100 (dual-core) and 5300 (quad-core) platforms or a flaw in Mac OS X memory handling.

More directly to blame, however, is Mac OS X Tiger's mishandling of CPU resources. The operating system engages in a bad practice known as "core swapping," Chambers says. The Apple software, released in 2005, is frequently unsure of when to keep a particular task on a particular core and sends the relevant data to another one of the eight cores, saturating the already constrained memory pipeline with redundant information.

Testers of the new Apple workstation are suggesting that buyers carefully evaluate the programs they run before buying the $1500 upgrade in the current software enviroment, as the extra resources were said to translate to "multi-threading muscle" only in certain circumstances.

Mac OS X Leopard may potentially solve the problem, suggests Chambers. The computer builder hasn't officially announced explicit support for more than four cores in its operating system.
  1. l008com 04/12, 05:23pm

    Good to know that macnn is looking for photographers for advice when it comes to memory management.

  1. hmurchison2001 04/12, 06:33pm

    Ummm the target demographic for an 8-core Mac Pro isn't a photo editor. I don't know what people really expected. I've never heard someone say "flattening my file in Photoshop took 10 straight hours of rendering"

    Use the right tool for the right job folks.

  1. himself 04/12, 07:18pm

    You obviously have no idea what professional photographers require in a computing system. Try working with multi-GB, 16bit/channel (or higher) RAW images in Aperture (or Photoshop), then you can possibly make an informed judgment.

  1. eldarkus 04/12, 08:36pm

    I am running Aperture & PS3 and working with 10-20MB 16 bit RAW files... on a MAC BOOK PRO!!! I sure as h*** dont need, nor would require that kind of beast for photography. Most photographers would not need that kind of machine.

    The machine should be aimed at video, 3D or high end DESIGN work. FYI: Photography does not equal design work.

    and maybe Apple just released this because the chip was available. Maybe the Mac Pros are going to get a revamp soon, so they're just milking it and getting braging rights to being the first to have the new 8 core chip. Let see.. Mac Pro released on Aug 2006. Apple has about a 9 month recycle time.. gee, could a new machine be coming out soon? Maybe at NAB??? No wait.. thats not about photographers. Thats about video broadcasting.

    So that is my informed judgement :) now pls excuse me.. I have to fire up my 20 xServe cluster to change the contrast & hue on a photo.

  1. petsounds 04/12, 09:49pm

    He mentioned editing multi-Gig files, not 10-20MB files. 10-20MB is tiny for high-res photography. I often work with 8-bit, 200-500MB TIFF files, and probably not at the res that high-end digital photographers are working at.

    However, I will agree that video editing and encoding is really where the multi-core environment can shine. I use a quad-core G5 in my production environment, and often am encoding FLVs and MPEGs concurrently, while also working on other tasks. The major bottleneck only becomes memory, which is what this article was noting.

    I am curious why Apple would release this 8-core beast, yet cage it with software (or hardware?) limitations. I'm aware that this is probably a stopgap measure to keep high-end pros happy until Apple ships Mac Pro redesigns with Leopard in October. Still though, the high price combined with the limited performance benefits mean this model will sit on the shelves more than Mr. Jobs would probably prefer.

  1. bobbyperu 04/12, 10:03pm

    I'm a little miffed why this uber-machine that I've been tasting on my lips for the last 6 months is realistically going to be a disappointment. Looks like I'll be going Quad-core and using that extra money instead on RAIDed Raptor drives and maxxing out the 16GB of memory, since OS 10.5 is being delayed until October because Apple spent too much time developing the iPhone.

    I shoot 39 megapixel digital and in 16-bit color, that makes for a 223 mb flat Tiff. In retouching, with layers, my files routinely run into 1.5GB each. Over a 6-day shoot, I'll have about 45 of these images to retouch and deliver to client. I have to do this efficiently enough to meet my current client's deadlines and leave time in the day to shoot the NEXT job.

    Excuse me eldarkus, but I use every bit of my current dual 2.5 G5 with twin 4-disk external RAID-0's. Clearly, we are two different kind of photographers and you have NO REASON to jump up on a soap box and denounce anyone looking for more power. My 120GB Aperture library REFERENCES 11 TERABYTES OF IMAGES.

    Apparently, you've never seen your Alpha computer process a commercial job for 70 hours straight as you're watching the clock, knowing exactly when that 500GB hard drive needs to be dropped off at FedEx so you can bill out the remainder of the job and get paid.

    I have 9 macs, it would be laughable if my most powerful machine was my laptop... please.

  1. bobbyperu 04/12, 10:04pm


  1. eldarkus 04/13, 09:31am

    Sorry, i meant to meantion that 10-20 MP files can quickly turn into 1-2GB in PS.

    and Bobby: Lets get serious here. How many people are working with 11 terrabyte libraries? And do you honestly need to load the entire library? Ever thought of splitting it up?

    It sounds like the work you do is seriously high end and NOT the what most main stream photographers do. Photography and Design are TWO DIFFERENT FIELDS!

    So Mr. 9 Macs, please realize that most people are not in your position and these "performance tests" are not a good comparison for what the machine is capable of. Aperture has had serious performance issues from the start. While Aperture is getting better (1.5), that is NOT a good application to use to run speed tests on the new Mac Pro. And CS 3 is still a beta so again.. not a good comparison.

    I was not denouncing anyone looking for more power, yet just adding my opinion about the speed tests. Bottom line is that multicore processers will not be much use to Aperture. Faster disks, fater memory and high end graphics cards.. most certainly!!

  1. Deal 04/13, 11:01am

    There is no doubt, some people will need this machine and some people wont. If nobody needed it, who would be selling it? Either way, you know who you are...

    Now, to the point of the article:

    Talk about missing the point. What they are saying is, if you need this speed for photography, don't buy this system. Well, what about when Leopard does come out and streamlines multi-core processing. This is obviously the direction Apple is going and will obviously be addressed.

    Maybe they think we'll save a bunch of money if we spend >$2500 on a quad now, then in 5 months turn around and spend >$3500 then. Think of how much faster we'll walk that that much less money in our pockets!

    This information was used to spit out a quick article. That's all.

    If you need the speed, buy the mucho-ocho-core Mac and in less than half a year get a wonderful speed boost that costs very little. In the mean time, take advantage of all the other speed enhancements that the system does give you which you can read about here:

  1. bobbyperu 04/13, 05:21pm

    Sorry, eldarkus, I didn't mean to jump on your case, but I didn't like the dismissive tone that 'who could possibly' need a machine like this... I'm surprised, frankly, that since you use Aperture that you don't immediately see the need in the fastest machine possible since that program is such a hog.

    I merely reference all of those images in my Aperture library, the TIFFS are stored on mirrored pairs of offline drives. The only purpose I have for Aperture right now is to catalog each years work, and to be able to search for images based on criteria. Splitting that up into separate libraries would complicate things unnecessarily, from the aspect of digital asset management. The 11 Terabytes is only since I started shooting digital 5 years ago.. I haven't even begun to drumscan the previous years of 35mm, 6x7, and 4x5 film. (slated as my mid-summer project this year)

    Even on my 24" iMac with 3GB of memory, and only a temporary edit library, Aperture is too slow to edit a job based on previewing and louping the actual RAW files from my 16mp Canons. It will certainly be nice when I do have enough power to do that, and perhaps my Quad 3.0 will be able to do that, although ideally if Apple could straighten out the code, editing would be best suited on the 24" iMac vs my premier retouching machine, as I'm often running scripts to prep & deliver one job while editing another.

    I'm glad this article was posted, because I live in the world of Photoshop and if an extra 4 processors doesn't improve the speed, then it's of no use to me. I did indeed redistribute the $1500 processor savings today on the full 16gb of RAM.

    I'm sure by this fall, when we find out if Leopard is going to take full advantage of those 8 processors, the current machine will be cheaper, or there will be a new bad-boy on the block. In the mean time, unless you're sequencing DNA, you could probably spend your money better elsewhere.

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