Re: Compiler performance tests on FreeBSD 10.0-CURRENT

On 2012-09-16 01:22, Luigi Rizzo wrote:
...
> the fact that the difference is so small is interesting,
> and it might almost suggests that the test is dominated by
> other factors than the compiler.

Yes, this result was more or less what I expected: runtime performance
is probably related more to hardware speed, and the efficiency of the
chosen algorithms in the kernel, than to the optimizations any current
compiler can produce.

Apparently our kernel hackers already produce quite efficient code. :)


> By chance do you have a
> way to produce other data points with different optimization
> levels in the compiler ?

I could re-run the tests with e.g. -O1 instead of -O2, or maybe even
-O0, though I am not sure if the kernel will compile correctly without
any optimization.  This will take a while though, and I am not sure if I
can borrow Gavin's machine long enough. :)

-Dimitry