Workstation, yes; Server, no.

The G5 is a gigantic improvement over the previous CPU in the PowerMac, the G4e. The G5 is one of the most superscalar CPUs ever, and has all the characteristics that could give Apple the edge, especially now that the clock speed race between AMD and Intel is over. However, there is still a lot of work to be done.

First of all, the G5 needs a lower latency access to the memory because right now, the integer performance of the G5 leaves a lot to be desired. The Opteron and Xeon have a better integer engine, and especially the Pentium 4/Xeon has a better Branch predictor too. The Opteron's memory subsystem runs circles around the G5's.

Secondly, it is clear that the G5 FP performance, despite its access to 32 architectural registers, needs good optimisation. Only one of our flops tests was " Altivectorized", which means that the GCC compiler needs to improve quite a bit before it can turn those many open source programs into super fast applications on the Mac. In contrast, the Intel compiler can vectorize all 8 tests.

Altivec or the velocity engine can make the G5 shine in workstation applications. A good example is Lightwave where the G5 takes on the best x86 competition in some situations, and remains behind in others.

The future looks promising in the workstation market for Apple, as the G5 has a lot of unused potential and the increasing market share of the Power Mac should tempt developers to put a little more effort in Mac optimisation.

The server performance of the Apple platform is, however, catastrophic. When we asked Apple for a reaction, they told us that some database vendors, Sybase and Oracle, have found a way around the threading problems. We'll try Sybase later, but frankly, we are very sceptical. The whole "multi-threaded Mach microkernel trapped inside a monolithic FreeBSD cocoon with several threading wrappers and coarse-grained threading access to the kernel", with a "backwards compatibility" millstone around its neck sounds like a bad fusion recipe for performance.

Workstation apps will hardly mind, but the performance of server applications depends greatly on the threading, signalling and locking engine. I am no operating system expert, but with the data that we have today, I think that a PowerPC optimised Linux such as Yellow Dog is a better idea for the Xserve than Mac OS X server.

References

Threading on OS X
http://developer.apple.com/technotes/tn/tn2028.html

Basics OS X
http://developer.apple.com/documentation/macosx/index.html


Mac OS X versus Linux
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  • mongo lloyd - Tuesday, June 7, 2005 - link

    Any reason for why you weren't using RAM with lower timings on the x86 processors? Shouldn't there at least have been a disclaimer? Reply
  • jhagman - Tuesday, June 7, 2005 - link

    OK, this clears it up, thanks.

    One little thing still, what is the number you are giving in the ab results table? Is it requests per second or perhaps the transfer rate?

    Reply
  • demuynckr - Tuesday, June 7, 2005 - link

    jhagman:
    As i mentioned before, we used gcc 3.3.3 for all linux, and gcc 3.3 mac compiler on apple, because that was the standard one.
    I did a second flops test with the gcc 4.0 compiler included on the Tiger cd, and the flops are much better when compiled with the -mcpu=g5 option which did not seem available when using the gcc 3.3 Apple compiler.
    As for ab i used these settings,
    ab -n 100000 -n x http://localhost/

    x for the various concurrencies: 5,20,50,100,150.
    Reply
  • spinportal - Monday, June 6, 2005 - link

    Guess there's no one arguing that the PPC is not keeping its paces with the current market, but rather OS/X able to do Big Iron computing. And if rumors be true, where will you be able to get a PPC built once Apple drops IBM for Intel?
    In a Usenet debate in 93, Torvalds and Tannenbaum go roasting Mach microkernel vs. the death of Linux. Seems Linus' work will be seeing more light of day, and Mach go the way of the dodo. Will Apple rewrite OS/X for Intel x86/64? As far as practical business sense, that's like shooting off one's leg foot.
    Reply
  • spinportal - Monday, June 6, 2005 - link

    Reply
  • jhagman - Monday, June 6, 2005 - link

    Could you please give the exact method of testing apache with ab? It is really hard to try to redo the tests when one does not know which methodology was used. The amount of clients and switches of ab would be appreciated.

    Also an answer to why Apple's newest gcc (4.0) was not used would be an interesting one and did you _really_ use gcc 3.3.3 and not Apple's gcc?

    Other than these omissions I found the article very interesting, thanks.
    Reply
  • demuynckr - Monday, June 6, 2005 - link

    Yes I have read the article, I also personally compiled the microbenchmarks on linux as well as on the PPC, and I can tell you I used gcc 3.3 on Mac for all compilation needs :). Reply
  • webflits - Monday, June 6, 2005 - link

    demuynckr, did your read the article?

    "So, before we start with application benchmarks, we performed a few micro benchmarks compiled on all platforms with the SAME gcc 3.3.3 compiler. "


    BTW I ran the same tests using Apple's version of gcc 3.3
    As you can see my 2.0Ghz now beats the 2.5Ghz on 5 of the 8 tests, and a 2.7Ghz G5 would be on par with the Opteron 250 when you extrapolate the results.

    Lets face it, Anandtech screwed up by using a crippled compiler for the G5 tests


    ----------------------------
    GCC 3.3/OSX 10.4.1/2.0GHz G5

    FLOPS C Program (Double Precision), V2.0 18 Dec 1992

    Module Error RunTime MFLOPS
    (usec)
    1 4.0146e-13 0.0140 997.2971
    2 -1.4166e-13 0.0108 648.4622
    3 4.7184e-14 0.0089 1918.5122
    4 -1.2546e-13 0.0139 1076.8597
    5 -1.3800e-13 0.0312 928.9079
    6 3.2374e-13 0.0182 1596.1407
    7 -8.4583e-11 0.0348 344.3954
    8 3.4855e-13 0.0196 1527.6638

    Iterations = 512000000
    NullTime (usec) = 0.0004
    MFLOPS(1) = 827.5658
    MFLOPS(2) = 673.7847
    MFLOPS(3) = 1037.6825
    MFLOPS(4) = 1501.7226
    Reply
  • demuynckr - Monday, June 6, 2005 - link

    Just to clear things up: on linux the gcc 3.3.3 was used, on macintosh gcc 3.3 was used (the one that was included with the OS).
    Reply
  • Joepublic2 - Monday, June 6, 2005 - link

    Wow, pixelglow, that's an awesome way to advertise your product. No marketing BS, just numbers! Reply

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