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
Mac OS X versus Linux
Lmbench 2.04 provides a suite of micro benchmarks that measure the bottlenecks at the Unix operating system and CPU level. This makes it very suitable for testing the theory that Mac OS X might be the culprit for the terrible server performance of the Apple platform.Signals allow processes (and thus threads) to interrupt other processes. In a database system such as MySQL 4.x where so many processes/threads (60 in our MySQL screenshot) and many accesses to the kernel must be managed, signal handling is a critical performance factor.
Larry McVoy (SGI) and Carl Staelin (HP):
" Lmbench measure both signal installation and signal dispatching in two separate loops, within the context of one process. It measures signal handling by installing a signal handler and then repeatedly sending itself the signal."
| Host | OS | Mhz | null | null call |
open I/O |
stat | slct clos |
sig TCP |
sig inst |
| Xeon 3.06 GHz | Linux 2.4 | 3056 | 0.42 | 0.63 | 4.47 | 5.58 | 18.2 | 0.68 | 2.33 |
| G5 2.7 GHz | Darwin 8.1 | 2700 | 1.13 | 1.91 | 4.64 | 8.60 | 21.9 | 1.67 | 6.20 |
| Xeon 3.6 GHz | Linux 2.6 | 3585 | 0.19 | 0.25 | 2.30 | 2.88 | 9.00 | 0.28 | 2.70 |
| Opteron 850 | Linux 2.6 | 2404 | 0.08 | 0.17 | 2.11 | 2.69 | 12.4 | 0.17 | 1.14 |
All numbers are expressed in microseconds, lower is thus better. First of all, you can see that kernel 2.6 is in most cases a lot more efficient. Secondly, although this is not the most accurate benchmark, the message is clear: the foundation of Mac OS X server, Darwin handles the signals the slowest. In some cases, Darwin is even several times slower.
As we increase the level of concurrency in our database test, many threads must be created. The Unix process/thread creation is called "forking" as a copy of the calling process is made.
lmbench "fork" measures simple process creation by creating a process and immediately exiting the child process. The parent process waits for the child process to exit. The benchmark is intended to measure the overhead for creating a new thread of control, so it includes the fork and the exit time.
lmbench "exec" measures the time to create a completely new process, while " sh" measures to start a new process and run a little program via /bin/ sh (complicated new process creation).
| Host | OS | Mhz | fork hndl |
exec proc |
Sh proc |
| Xeon 3.06 GHz | Linux | 3056 | 163 | 544 | 3021 |
| G5 2.7 GHz | Darwin | 2700 | 659 | 2308 | 4960 |
| Xeon 3.6 GHz | Linux | 3585 | 158 | 467 | 2688 |
| Opteron 850 | Linux | 2404 | 125 | 471 | 2393 |
Mac OS X is incredibly slow, between 2 and 5(!) times slower, in creating new threads, as it doesn't use kernel threads, and has to go through extra layers (wrappers). No need to continue our search: the G5 might not be the fastest integer CPU on earth - its database performance is completely crippled by an asthmatic operating system that needs up to 5 times more time to handle and create threads.
Facebook
Twitter
RSS
116 Comments
View All Comments
seanp789 - Saturday, June 4, 2005 - link
well thats great and all but yours news says apple is switchign to intel so i dont think much will be changing in the power pc lineupBrazilian Joe - Saturday, June 4, 2005 - link
I would like to see this Article re-done, with more benches to give a clearer picture. I think MACOS X should be pitched against Darwin in the PPC platform, since there may be hidden differences. Darwin works on x86 too (and x86_64?), it would be very interesting to see the SAME OS under the Mac Platform running on different hardware. And having the software compiled with the same compiler present on Darwin, we should get a more consistent result. Linux and BSD should not be ditched, however. The perfornance difference Of linux/FreeBSD/OpenBSD in PPC vs PC is also a very interesting subject to investigate.I think this article, along with all the complaints of inconsistency in the results, sohuld fuel a new series of articles: One, Just comparing Darwin/MacOS X on Both platforms. Another For Linux, using a GCC version as close as possible to that used on Darwin. Another for FreeBSD, and yet another for OpenBSD. The last article Would get everything and summarize. I think this would be much more complete and satisfying/informative for the reader crowd.
iljitsch - Saturday, June 4, 2005 - link
There seems to be considerable confusion between threads and processes in the review. I have no trouble believing that MacOS doesn't do so well with process gymnastics, but considering the way Apple itself leverages threads, I would assume those perform much better.I don't understand why Apache 1.3 was used here, Apache 2.0 has much better multiprocessor capabilities and would have allowed to test the difference between the request-are-handled-in-processes and requests-are-handled-in-threads ways of doing things.
Phil - Saturday, June 4, 2005 - link
#79: Wow. I had no idea that they were actually going to do it, I had assumed that it was typical industry nonsense!If this is true, then IMHO Apple won't be in much of a better position (with regards to this article) as they'll still need to work on the OS, regardless.
Can anyone speculate as to why they *really* want to switch to x86/Intel? I wonder if they'll consider AMD too...
rorsten - Saturday, June 4, 2005 - link
Uhm, the estimation for power consumption is completely wrong. The only significant CMOS power consumption - especially for an SOI chip - is the current required to charge or discharge the gates of the FETs, which only happens when a value changes (the clock accounts for most of the power consumption on a modern synchronous chip). Since we're talking about current only, this is purely resistive power, I^2R style, and since the current is related to the number of transitions per second, increasing the clock rate linearly increases the current which quadratically increases the power consumption.kamper - Saturday, June 4, 2005 - link
Here's another story about Apple and Intel from cnet:http://news.com.com/Apple+to+ditch+IBM%2C+switch+t...
Interesting in the context of this article but I won't believe it without much more substantial proof :)
+1 on getting a db test using the same os on all architectures whether it be linux or bsd
+1 on fixing the table so that it renders in firefox
shanep - Saturday, June 4, 2005 - link
Re: NetBSD.Sorry, I just noticed it is not supported yet by NetBSD.
Forget I mentioned it.
shanep - Saturday, June 4, 2005 - link
"Wessonality: Our next project if we can keep the G5 long enough in the labs."How about testing these machines with NetBSD 2.0.2 to keep the hardware comparison on as close an equal footing as possible.
This should mostly remove many red herrings associated with multiple differences in software across different hardware.
michaelok - Saturday, June 4, 2005 - link
"i've had for awhile about OS X server handling large numbers of thread. My OS X servers ALWAYS tank hard with lots of open sessions, so i keep them around only for emergencies. T"Moshe Bar (openMosix) has been an avid Mac follower for years, I see he has a few suggestions for OSX, including ditching the Mach so you can run FreeBSD natively, which has much better peformance. In fact, thread performance is one of FreeBSDs strong points, although Linux has largely caught up.
Also research his Byte articles, you can see how a proper comparison can be done, although he does not claim to be a benchmarking expert.
http://www.moshebar.com/tech/?q=node/5
http://www.byte.com/documents/s=7865/byt1064782374...
johannesrexx - Saturday, June 4, 2005 - link
Everybody should use Firefox by default because it's far more secure. Use IE only when you must.