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From Vince Weaver:
I've been running the SPEC CPU 2006 benchmarks under valgrind (doing some
work on my BBV generating plugin).
There are two benchmarks that have issues, and I thought I'd share them
here for future reference.
1). zeusmp - does not run
It has a 1GB data segment, which valgrind cannot handle on a 32-bit
CPU.
2). dealII - runs forever, never ending
It took a while, but I tracked this down to a 64bit/80bit
floating point issue.
The code in the QGauss<1>::QGauss() function has some code like this:
const long double tolerance = std::max (static_cast<long double>
(std::numeric_limits<double>::epsilon() / 100),
static_cast<long double>(std::numeric_limits<long
double>::epsilon() *5));
do {
....
various fp operations
....
} while (abs(p1/pp) > tolerance);
The tolerance in this case is being set to ~2.22e-18, but the
abs(p1/pp) value never gets below ~2.586e-17 under valgrind.
[This is because Valgrind only uses 64-bit FP values on x86, not 80-bit
values.]
This is similar to an issue that happens with the "art"
benchmark on SPEC CPU 2000, but in the "art" case it only
makes the code take longer to finish; this "dealII" problem
makes the benchmark loop forever.
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