Re: Interesting ubench scores for FreeBSD 4.11, 5.4, 6.0beta3 and DFly-Preview

[Michel Talon <talon@xxxxxxxxxxxxxxxx>]

Kris Kennaway wrote:

> When using the same binary, the CPU scores are statistically
> indistinguishable between the different FreeBSD versions.  This makes
> sense since there's little kernel involvment in running userland
> integer/FP computations.  When running the gcc 2.95 binary all
> versions of FreeBSD were 31% *faster* on this test than when running a
> gcc 3 binary (both compiled with -O only).
>
> FreeBSD 5.x and above show a 6.3% drop on the memory test relative to
> 4.x (with the same 4.x binary).  I reran ubench with kernel profiling
> enabled and found that this drop is mostly due to the vm locking
> present in FreeBSD 5 and above (via vm_fault).  This locking is also
> responsible for the dramatic performance increases on SMP machines
> seen in other benchmarks, so it would be more interesting to test on
> SMP machines.  I'm not set up to do this on my hardware though.

Wonderful exposition, Kris, and a proof that benchmarks have to ba taken 
with a grain of salt. It may also depend considerably on the hardware, 
for example AMD machines have faster locking primitives than Intel ones,
and hyperthreading can degrade considerably the result. To give a 
perfectly subjective appreciation, and with a limited range of desktops 
and laptops, for me FreeBSD-5.4 works very well, and certainly much
better than FreeBSD-4. If it has a solid contender, it may be
DragonFly, but much more obviously Linux, kernel 2.6.