Phoronix Benchmarks: Waht's wrong with FreeBSD 8.0?

[Alexander Motin]

Johan Hendriks wrote:
>> If somebody still have questions, after some UFS parameters tuning I've
>> got with the same tiotest tool:
>> - Random Write latency - 15us,
>> - Random Read latency - 7us.
> 
> What kind of UFS parameter tunings.

To maximize write-back delay. I've mounted file system asynchronously
and increased vfs.dirtybufthresh and vfs.hidirtybuffers values ten times.

> If things ar tuned for old hardware, which hardware are we talking about
> i386? Or i486?
> Maybe we should set the defaults for AMD64 in a way that modern hardware
> can handle.
> 
> AMD64 is a for modern hardware, it does not run on a pentium3.

It is not a tuning for hardware. It is mostly tuning for sanity.
Enormous write-back without using additional technics increase chance of
data loss on power-outage, but doesn't give principal effect under
constant load. This test is so easy to cheat, as it runs only few
seconds and completely ignores cache effects. I believe that the same
test with work file size increased by 100 times would show completely
different results.

-- 
Alexander Motin