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EGCS improves Fortran Performance on the Alpha, but not enough (fwd)
- To: egcs at cygnus dot com
- Subject: EGCS improves Fortran Performance on the Alpha, but not enough (fwd)
- From: "Luke A. Lonergan" <luke at navo dot hpc dot mil>
- Date: Sun, 1 Mar 1998 21:43:55 -0600 (CST)
---------- Forwarded message ----------
Date: Sun, 1 Mar 1998 21:26:42 -0600 (CST)
From: Luke A. Lonergan <luke@mail>
To: Beowulf <beowulf@cesdis.gsfc.nasa.gov>
Subject: EGCS improves Fortran Performance on the Alpha, but not enough
I just installed EGCS 1.0.1 on our Dec Alpha (PC164/EV5.6 at 433 MHz) running
RedHat 5.0. The benchmark that I published to the newsgroup
comp.os.linux.alpha a while ago now runs at 57.4 MFlops, versus the 32 MFlops
it used to under g77 version 0.5.22. I have attached that benchmark to
this E-mail. Please download and try to improve the performance.
Here are benchmark results for a variety of machines, CPU speeds and memory
bus speeds. The Pentium II results were all done on a machine with the ABIT
LX6 motherboard, which easily allows for setting different CPU and bus speeds
from the BIOS menu. This allowed runs of a Pentium II at 200 MHZ for a direct
comparison to a Pentium Pro. The Pentium II CPU used is a 0.35u version sold
as a 266 MHz with a 512 KB cache running at half CPU speed. The Pentium
Pro uses a full speed cache of 512 MB.
Processor Memory Motherboard Compiler Speed C
Speed Speed (MHz) Model MFlops Version
-------------------------------------------------------------------------------
Alpha433 66 PC164 G77 0.5.22 32 57.4
PPro 200 66 AMI Goliath G77 0.5.22 42.3 50.1
PII 200 66 ABIT LX-6 Old G77 w/2.7.2 40.4 50.0
PII 300 66 ABIT LX-6 Old G77 w/2.7.2 51.9 61.2
PII 300 75 ABIT LX-6 Old G77 w/2.7.2 54.4 64.8
PII 338 75 ABIT LX-6 Old G77 w/2.7.2 57.0 67.3
Alpha433 66 PC164 EGCS 1.0.1 G77 57.4 57.4
PII 333 83 ABIT LX-6 Old G77 w/2.7.2 59.9 71.4
Origin 2000 100 195MHz CPU f77 7.2 135 97.7
Alpha450 66 Cray T3E-900 f90 148 N/A
T90 500? ?? Cray T916 f90 997 41.4
Notice how fast the C version of the code runs on the Alpha (57.4 MFlops).
This is exactly the same speed I got out of it with gcc version 2.7.2.2.f.2.
The C version is very ugly compared to the Fortran, so I am glad to see the
Fortran compiler "catch up" on the Alpha. However, the C version on the Intel
machines is a lot faster! I have yet to try the EGCS Fortran compiler on the
Pentium Pro/II machines.
Given that others who ran the benchmark on the same kind of Alpha machine
using the NDP Fortran compiler were able to get 80 MFlops, there seems to
be a great deal more that could be done with EGCS to get it to generate
optimized floating point code for the Alpha. EGCS did greatly improve the
Fortran picture on Linux/Alpha however, going from 32 to 57.4 MFlops.
----
Luke Lonergan, Grumman Data Systems Corporation Voice: 601-688-3666
Technical Evaluation Center Manager Email: luke@navo.hpc.mil
NAVO MSRC PET Program, Stennis Space Center, MS Fax: 601-689-0400
bench_1.tar.gz