Date: Mon, 09 Feb 2004 16:20:54 -0500 From: "Juan Tumani" <jtumani55@hotmail.com> To: freebsd-hackers@freebsd.org Subject: FreeBSD 5.2 v/s FreeBSD 4.9 MFLOPS performance (gcc3.3.3 v/s gcc2.9.5) Message-ID: <BAY12-F37zmBUw7MurD00010899@hotmail.com>
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Hi,
I have an Intel D845GE m/b w/ a P4 1.7 CPU and I have the box setup to dual
boot
to either 4.9 or 5.2. Both OS are right off the latest posted iso CD image,
i.e., no updates,
no kernel tweaks, everything vanilla right out of the box. I compiled
flops.c on both 4.9
and 5.2 and the 5.2 performance is less than half that of 4.9: 760 MFLOPS on
4.9 v/s
340 MFLOPS on 5.2.
I tried turning off the SMP and other kernel tweaks and no improvement in
5.2. I then
downloaded and installed gcc295 on the 5.2 machine and that fixed the
problem. So
now all I have to do is figure out the gcc 3.3.3 switches to make it run
like gcc 2.9.5 or
figure out how to rebuild 5.2 w/ gcc 2.9.5 :-).
Anyone know what's going on w/ gcc 3.3.3 ?
%gcc295 flops.c -o flops
%./flops
FLOPS C Program (Double Precision)
Version 1.2, 29 Feb 1992
PI: Program = 3.14159265358999429
PI: Reference = 3.14159265358979312
PI: Error = 2.0117e-13
Area: Program = 0.50000000000008060
Area: Reference = 0.50000000000000000
Area: Error = 8.0602e-14
Iterations = 20000000
BenchTime(usec) = 0.0013
Scalar MFLOPS = 760.2353
%gcc flops.c -o flops
%./flops
FLOPS C Program (Double Precision)
Version 1.2, 29 Feb 1992
PI: Program = 3.14159265358999429
PI: Reference = 3.14159265358979312
PI: Error = 2.0117e-13
Area: Program = 0.50000000000008060
Area: Reference = 0.50000000000000000
Area: Error = 8.0602e-14
Iterations = 20000000
BenchTime(usec) = 0.0029
Scalar MFLOPS = 339.4571
%
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