The Test

The goal today is to benchmark our newest Pentium M Dothans of both the 400MHz and 533MHz front side bus. We would like to see how these processors compare to the better-performing Athlon 64 and Pentium 4 processors available today, particularly for the same price category. We will also look at how the higher clocked front side bus speed, different memory speeds and different compilers affect our benchmark results.

 Performance Test Configuration
Processor(s): AMD Athlon FX-53 (130nm, 2.4GHz, 1MB L2 Cache, Socket 939)
AMD Athlon 64 3800+ (130nm, 2.4GHz, 512KB L2 Cache)
AMD Athlon 64 3500+ (130nm, 2.2GHz, 512KB L2 Cache)
AMD Athlon 64 3200+ (90nm, 2.0GHz, 512KB L2 Cache)
Intel Pentium 4 Extreme Edition 3.4GHz (130nm, 512KB L2 Cache, 2MB L3 Cache)
Intel Pentium 4 560 3.6GHz (90nm, 1MB L2 Cache)
Intel Pentium M 765 2.1GHz (90nm, 2MB L2 Cache, 533FSB)
Intel Pentium M 755 2.0GHz (90nm, 2MB L2 Cache, 400FSB)
RAM: 2 x 512MB Mushkin PC-3200 CL2 (400MHz)
2 x 512MB Corsair PC2-5400 CL3 (475MHz)
Motherboards: DFI LanParty 915P-T12 (Socket 775)
MSI K8T Neo2 (Socket 939)
Memory Timings: Default
Operating System(s): SuSE 9.1 Professional
Kernel 2.6.5-7.108
Compiler: dave:~ # gcc - v
Reading specs from /opt/gcc-mainline/lib/gcc/i586-suse-linux/3.4.1/specs
Configured with: ../configure - enable-threads=posix - prefix=/opt/gcc-mainline - with-local-prefix=/usr/local - infodir=/opt/gcc-mainline/share/info - mandir=/opt/gcc-mainline/share/man - libdir=/opt/gcc-mainline/lib - libexecdir=/opt/gcc-mainline/lib - enable-languages=c,c++,f77,objc,java,ada - enable-checking - enable-libgcj - with-gxx-include-dir=/opt/gcc-mainline/include/g++ --with-slibdir=/lib - with-system-zlib - enable-shared --enable-__cxa_atexit i586-suse-linux
Thread model: posix
gcc version 3.4.1 20040508 (prerelease) (SuSE Linux)
Intel Compiler: dave:/opt/intel_cc_80/bin # ./icc -v
Version 8.1

As you will see from the specifications above, we are recycling most of our benchmarks from the last Linux CPU roundup that we published a few months ago. The two newcomers to the benchmark are the 2.1GHz 533FSB Dothan Pentium M and the 2.0GHz 400FSB Dothan Pentium M. Both processors use the desktop configuration, Socket 479. Socket 479 processors are somewhat difficult to find right now, although they similarly reflect the performance of their Socket 478 counterparts. Unfortunately, the Dothan/Banias Socket 478 pinout is different electrically than the typical desktop Socket 478, and thus you will need to use a Socket 479 board with a Socket 479 Dothan if you plan on using any of these Pentium M's in your desktop anytime soon.

Click to enlarge.

Looking at the CPU proc information we can discern the following:
dave:~/bench/gcc/linux-2.6.4 # cat /proc/cpuinfo 
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 13
model name      : Intel(R) Pentium(R) M processor 2.10GHz
stepping        : 6
cpu MHz         : 2104.892
cache size      : 64 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags           : fpu vme de pse tsc msr mce cx8 sep mtrr pge mca cmov pat clflush
                  dts acpi mmx fxsr sse sse2 ss tm pbe tm2 est
bogomips        : 4177.92
The bogomips score seems fairly accurate; the 3.6GHz Nocona reports about 7200BMIPS per physical processor. However, note that there are no SSE3 enhancements, HyperThreading or EM64T addressing capability. All desktop Pentium M processors today are derived from the blade server market and their feature sets reflects that - blade servers are designed to be small, fast and cool; putting 8GB of memory in a blade would not make a lot of sense.

As you can also see from the information above, our Dothan 2.1GHz is in the 6th stepping, "F". The processor utilizes 64K of L1 cache and 2MB of L2 cache. The DFI motherboard that we use in this analysis keeps our Dothan bus at 100MHz while pushing the clock multiplier up to 21X; thus, effectively running it at 2.1GHz with 400MHz FSB. During the test, we also clock the bus at 133MHz and run the multiplier at 16X, which effectively runs our CPU at 2133MHz with the full 533FSB. This also skews our memory clock a bit - in the first 400MHz configuration, we are running DDR333 (100MHz with a 5:3 ratio). In the second configuration, we use 133MHz at a 4:3 ratio. This is perfectly normal behavior, although keep in mind that the default configuration with our set up runs at DDR200 with the 400MHz FSB. Keep in mind also that we anticipate these lower memory clocks to pinch the Dothan's performance in the long run.

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  • Lynx516 - Monday, December 27, 2004 - link

    What yozza says is true gcc 3.4.1 is old especially a pre release. As yozza said it has some bugs in it with respect to the pentiu_m march flag.I have been running gcc 3.4.3 for atleast 2 months and i definatly was not one of the first to use it
  • KristopherKubicki - Monday, December 27, 2004 - link

    Yozza: I made some corrections. Saying GCC 3.4.1 is "pretty old" seems pretty hard for me to swallow, but the rest of what you say seems correct. I would be interested in seeing your P-M compile time benchmarks.

  • Yozza - Sunday, December 26, 2004 - link

    The march=pentium-m flag was pretty broken on earlier gcc 3.4 releases, and it seems that you're using quite an early "3.4.1 (prerelease)" version, which could explain a few things, especially your TSCP benchmarks, where the Pentium-M is the only one to have its performance _decrease_ with optimised (march=pentium-m) compiler flags. This clearly indicates some issues with pentium-m optimisations in your gcc revision (3.4.1 is pretty old these days).

    The extremely slow kernel compile time is especially surprising though. I did some test just now on my 1.7GHz Banias P-M, and the kernel compile times do NOT appear to correspond with your results. So I guess something seems amiss with your system configuration.

    There was certainly some pretty impressive performance in the integer-dependent tests such as the database one -- we already know that the P-M's fp performance isn't that great, which explains some of the more fp-dependent benchmark results. I for one was pretty impressed by its performance in the majority of the benchmarks and by its scaling possibilities, both wrt FSB/memory and core freqs. If only Intel would upgrade the platform to 800MHz FSB with dual channel DDR400; such a configuration would be appear to hold a lot of promise.

    The argument that "Dothan is adherently a linear processor" doesn't hold water either (it should be "inherently" too), since the kernel compile uses one thread by default. Regardless, it should have been possible to test different CPU schedulers to determine how well Dothan deals with multi-tasking loads, particularly wrt compile times by comparing different "MAKEOPTS=-jX" settings. Behaviour under such loads is as dependent on the CPU scheduler as it is on the CPU itself anyway.

    Hence, clearly, the comment "When we stack multiple jobs on the processing queue, Dothan spends a huge majority of its time swapping around" is flawed and incorrect. The implication that the CPU 'swaps around' somewhat like memory paging to disk is rather inaccurate to say the least.
  • larson0699 - Sunday, December 26, 2004 - link

    "...The only additional offering that the 855GME feature provides is a 64-bit PCI-X (not to be confused with PCI-Express) bus..."

    PCI-X is a "feature" of the 6300ESB ("Hance Rapids") southbridge, NOT the 855GME northbridge.

    Other makers used the standard ICH5 southbridge, hence no PCI-X slots.

    Such a system would be awesome for a mini RAID server. An adapter from 3Ware would be the perfect utilization of the PCI-X slot provided. Ahh...
  • vaystrem - Sunday, December 26, 2004 - link

    Why not Gentoo?

    You could do two boxes - compile the entire OS optomized for the Pentium M with latest GCC revision and do the exact same for the Athlon 64 Box.

    That would be a lot more interesting comparison and useful than doing these benchmarks on top of Suse whose default optomizations are certainly hurting the PentiumM.

  • bhtooefr - Saturday, December 25, 2004 - link

    BTW, I mean that maybe Intel shut them down...
  • bhtooefr - Saturday, December 25, 2004 - link

    Hmm... maybe you're right... After all, it seemed that PowerLeap was dodging my questions about their P-M adaptor (and then tried to pimp the PL-AXP (basically a golden fingers card for Socket A) - if I wanted to unlock an AXP, I'd get a pencil ;-))...

    Here's the chat:
  • sprockkets - Saturday, December 25, 2004 - link

    Oh well, I just looked at SuSE 9.1 again and 9.2 has the ability with kpowersave to select easily the profiles it will use to run, and will say what processor speed it currently is throttling to.
  • ElFenix - Saturday, December 25, 2004 - link

    i'd like to point out that 'heat sink' is actually two words. thanks.
  • KristopherKubicki - Saturday, December 25, 2004 - link

    bhtooefr: I am pretty sure intel wont let them do that.


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