No more mysteries: Apple's G5 versus x86, Mac OS X versus Linux
by Johan De Gelas on June 3, 2005 7:48 AM EST- Posted in
- Mac
The G5 as Server CPU
While it is the Xserve and not the PowerMac that is Apple's server platform, we could not resist the temptation to test the G5 based machine as a server too. Installed on the machine was the server version of Mac OS X Tiger. So in fact, we are giving the Apple platform a small advantage: the 2.5 GHz CPUs are a bit faster than the 2.3 GHz of the Xserve, and the RAM doesn't use ECC as in the Xserve.
| Dual G5 2,5 GHz PowerMac | Dual Xeon DP 3,6 GHz (HT on) | Dual Xeon DP 3,6 GHz (HT out) | Dual Opteron 2.4Ghz | |
| 1 | 192 | 286 | 287 | 290 |
| 2 | 274 | 450 | 457 | 438 |
| 5 | 113 | 497 | 559 | 543 |
| 10 | 62 | 517 | 583 | 629 |
| 20 | 50 | 545 | 561 | 670 |
| 35 | 50 | 486 | 573 | 650 |
| 50 | 47 | 495 | 570 | 669 |
Performance is at that point only 1/10th of the Opteron and Xeon. We have tested this on Panther (10.3) and on Tiger (10.4.1), triple-checked every possible error and the result remains the same: something is terribly wrong with the MySQL server performance.
SPEC CPU 2000 Int numbers compiled with GCC show that the G5 reaches about 75% of the integer performance of an equally clocked Opteron. So, the purely integer performance is not the issue. The Opteron should be quite faster, but not 10 times faster.
We checked with the activity monitor, and the CPUs were indeed working hard: up to 185% CPU load on the MySQL process. Notice that the MySQL process consists of no less than 60 threads.
| Concurrency | Dual Powermac G5 2.5 GHz (Panther) | Dual Powermac G5 2.7 GHz (Tiger) | Dual Xeon 3.6 GHz |
| 5 | 216.34 | 217.6 | 3776.44 |
| 20 | 216.24 | 217.68 | 3711.4 |
| 50 | 269.38 | 218.32 | 3624.63 |
| 100 | 249.51 | 217.69 | 3768.89 |
| 150 | 268.59 | 256.89 | 3600.1 |
The new OS, Tiger doesn't help: the 2.7 GHz (10.4.1) is as fast as the 2.5 GHz on Panther (10.3). More importantly, Apache shows exactly the same picture as MySQL: performance is 10 times more worse than on the Xeon (and Opteron) on Linux. Apple is very proud about the Mac OS X Unix roots, but it seems that the typical Unix/Linux software isn't too fond of Apple. Let us find out what happened!
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mongo lloyd - Tuesday, June 7, 2005 - link
At least the non-ECC RAM, that is.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?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?
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.
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.
spinportal - Monday, June 6, 2005 - link
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.
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 :).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
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).