Performance problems on Intel but not AMD... strange

[Chris Roe]

We have run into a problem with a few of our clients running Intel
Pentium 4 (no hyperthreading) processors. Our web application under
tomcat runs 20 - 30% slower on Intel (benchmarks scores are available)
than a comparable AMD processor. Our shop uses AMD Athlon processors and
we have no such performance problems at all.

We have had clients come to our shop to verify that the application is
indeed faster here and they always say that it is significantly faster.

We have developed benchmarks for certain parts of our system (formula
calculation, and page rendering) and run them on an AMD 2500+ and an
Intel P4 2.4 Ghz . According to all industry standard (SiSoft Sandra,
etc) benchmarks we have come across, these machines should perform
roughly the same, with the AMD performing slightly (5-10%) above the Intel.

Has anyone come across this problem before?? Are there certain
operations or combinations of operations in Java that are significantly
slower on the Intel??

We are seeing this on both the Client and Server VMs. All machines are
running JDK 1.4.2_04 on Windows XP SP 1.

Any help would be greatly appreciated.

- Chris

 

[Wee Jin Goh]

We have run into a problem with a few of our clients running Intel
Pentium 4 (no hyperthreading) processors. Our web application under
tomcat runs 20 - 30% slower on Intel (benchmarks scores are available)
than a comparable AMD processor. Our shop uses AMD Athlon processors and
we have no such performance problems at all.

We have had clients come to our shop to verify that the application is
indeed faster here and they always say that it is significantly faster.

We have developed benchmarks for certain parts of our system (formula
calculation, and page rendering) and run them on an AMD 2500+ and an
Intel P4 2.4 Ghz . According to all industry standard (SiSoft Sandra,
etc) benchmarks we have come across, these machines should perform
roughly the same, with the AMD performing slightly (5-10%) above the Intel.

Has anyone come across this problem before?? Are there certain
operations or combinations of operations in Java that are significantly
slower on the Intel??

We are seeing this on both the Client and Server VMs. All machines are
running JDK 1.4.2_04 on Windows XP SP 1.

Any help would be greatly appreciated.

- Chris

Yes, I've encountered this problem many times. The P4 and Athlon have
very dissimilar architectures. http://www.arstechnica.com has a rather
good overview of the two architectures in the section called CPU Theory
and Praxis. I suggest you give that a read.

The P4 does well in benchmarks like SiSoft Sandra and loop intensive
code because it has a higher clock frequency than a comparable Athlon
XP. But once you start throwing branches (if-else statements) in there
which is unavoidable in some programs, you'll start to see the P4
stumble. There are many other scenarios where the P4 is very weak
comparped to the Athlon.

But without further details of what your app does, its hard to say why
the P4 is slower.

Wee-Jin