On Mon, 29 Dec 2008, Christian Weisgerber wrote:
The archivers/lzo2 port runs a series of regression tests after the
actual build. These tests show extremely divergent behavior on
different machines. There are two types of machines:
Type #1:
Running the tests takes roughly the same time as configure and
compile did, whether it's 30 seconds on a fast machine or 10
minutes on an old slow one.
Type #2:
Running the tests takes much, much, MUCH longer.
I've tried this across alpha, amd64, i386, and sparc64, partially
on FreeBSD, partially on OpenBSD. The operating system doesn't
matter and there is no pattern related to endianness or 32/64 bits.
You can find machines that are the same architecture (e.g. amd64)
and are of similar overall speed (e.g. an Intel Xeon Xeon E5405 and
an AMD Phenom 9350e) and one of these machines will be type #1 and
the other will be #2 and take _a hundred_ times longer to run the
tests. A hundred times.
I have never seen anything like this before.
It might be good first to rule out compiler / library differences.
First, can you isolate a single lzo command / input combination whose time
differs dramatically? This would simplify tests compared to running the
whole test suite. (It should be easy because it looks like the test suite
prints the time for each test.) It might also simplify things to work on
one "fast" and one "slow" machine.
Then try copying the lzo binary from the "fast" machine to the "slow"
machine (and vice versa) and see if the same test speeds up with the
copied binary. If not, try again with the binary statically linked. If
still not, it would be good to have a copy of the binary made available,
along with more information about the "fast" and "slow" machines (CPU,
amount of memory, load on the machine, kernel version, disk, etc).
If the copied binary isn't faster than the natively produced one, then it
would be good to have information about the compiler options, versions,
etc.
--
Nate Eldredge
neldre...@math.ucsd.edu
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