Thomas Backman wrote:
On Nov 30, 2009, at 9:47 AM, O. Hartmann wrote:
I'm just wondering what's wrong with FreeBSD 8.0/amd64 when I read the
Benchmarks on Phoronix.org's website. Especially FreeBSD's threaded I/O shows
in contrast to all claims that have been to be improoved the opposite.
Corrected link:
http://www.phoronix.com/scan.php?page=article&item=freebsd8_benchmarks&num=1
And yeah, quite honestly: disk scheduling in FreeBSD appears to suck... The
only reason I'm not switching from Linux. :(
About the only useful result of the "Phoronix benchmark suite" in
general is that benchmarking is hard, and that though tedious,
statistical analisys and multiple runs actually have a realistic
purpose. I suspect their runs have a very large variance between tests
and are only useful in "order-of-magnitude" sort of comparisons.
Most of their CPU-bound benchmarks therefore show results with
insignificant differences, and most of the others benchmark the
compilers. On the other hand, disk IO benchmarks like
http://www.phoronix.com/scan.php?page=article&item=freebsd8_benchmarks&num=7
reflect the real state of the things, which can be easily demonstrated
by a large number of other benchmarks (e.g. blogbench). AFAIK there is
some speculation among developers about why is this so, but nothing
definite yet.
For what it's worth, ZFS effectively does a fair bit of its own IO
scheduling, so persons interested in this particular aspect should also
try the tests with ZFS. My own tests (with other benchmarks) show that
ZFS helps significantly, though the cumulative result is still
significantly worse than Linux's.
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