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.

Index Motherboard Details
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  • Adul - Friday, December 24, 2004 - link

    stephenbrooks "superlinearly" even a word? Though I do understand what you mean.
  • KristopherKubicki - Friday, December 24, 2004 - link

    abakshi: Intel roadmaps say only DDR1 for 915GL.

  • stephenbrooks - Friday, December 24, 2004 - link

    The Pentium M scales superlinearly with frequency in a few of the time vs. clock-speed benches (and I'm not talking about the 400->533 FSB improvement), which is pretty interesting. I wouldn't have expected a chip like this to get more efficient at _higher_ clocks.
  • abakshi - Friday, December 24, 2004 - link

    Well FSB533 is here, but 800 would be a more significant move with Dothan. A P-M with FSB800, even DDR400 let's say (rather than the DDR2 that should be supported by using a 915 northbridge), and higher clockspeeds - maybe about 2.4-2.6 Ghz - would be amazing.

    Linux performance will of course depend on other factors such as those mentioned in the article, but the performance under Windows of even the FSB400 2.0 Dothan is awesome -- when overclocked to 2.4Ghz, it's able to keep up with, and at times beat, the latest P4 Prescott and EE's, and A64's, for tasks like gaming:
  • Lonyo - Friday, December 24, 2004 - link

    If Intel gave it a FSB and memory speed boost (ie: 533MHz or 800MHz FSB) and DDR533+, then Dothan could really be something.
    With Intels talk of dual core processors, a dual core Dothan, with its low heat output, would be awesome (but costly with 2MB of cache).
    2x30w = 60w = less than Prescott.

    It looks promising, if only Intel would bring it to the affordable desktop :(
  • VortigernRed - Friday, December 24, 2004 - link

    "Although it holds up well against an Athlon 64 3200+,"

    Although the Dothan looks to be a superb chip you are certainly overstating its performance here, this is comment is WRT the Shake benchmarks and, effectively, the A64 3200 is twice as fast as the dothan. This would be like saying, for example, a R9800XT holds up well against an X800XT or an AXP2200+ holds up well against a A64 3800+ :-)

    Also whilst the DDR400 does improve performance it can't help the Dothan where it is really far behind, the kernel compile benchmarks, for instance, it is still 3x slower than any of the other chips on the chart.

    Dothan (or really its derivatives) have loads of potential to compete with the A64 on all fronts (Performance, power, heat, with Intels manufacturing, even cost) given enough effort by Intel (which I'm sure they are doing). I can hardly wait to see widespread adoption on the desktop and, frankly, to see the back of the P4. A desktop Celeron PM (1MB l2, lower FSB) could be the new overclocking king.
  • bersl2 - Friday, December 24, 2004 - link

    You might want to ask on the GCC mailing lists ( about --march=pentium-m.

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