[PATCH] ipsum_calc_block: Optimize size and speed

[Ondrej Filip]

On 23.4.2010 18:32, Ondrej Zajicek wrote:
> On Fri, Apr 23, 2010 at 03:20:55PM +0200, Martin Mares wrote:
>> Hello!
>>
>>> Fairly, I once had the same idea for Quagga but found all those extra tests and
>>> additions were much slower(I benched it). Just look at the number of extra ops one
>>> has to do in the current code.
>>> If you want to do it faster you have to go ASM. It would be easy to
>>> add support for that too but it can wait.
>>
>> My primary reaction was "If something isn't broken, don't fix it." I.e.,
>> unless you have good reasons for rewriting a piece of code, don't do that.
>>
>> Your version is more readable and I would be in favour of accepting it,
>> but I would still like to see at least a very simple benchmark which shows
>> that it is not significantly slower.
> 
> I was curious enough to do some benchmarks and got these results:
> 
> Intel Atom:	suggested code ~ 1.2* faster
> AMD Geode:	no diference
> MIPS ADM5120:	old code ~ 1.2* faster
> 
> So there isn't really difference in performance of both
> implementations. Even on slow embedded AMD Geode CPU, it gives
> ~ 180 MB/s.
> 

Hmm, so there is no major reason for change. I would really support
dont-fix-whats-not-broken approach. And also we should keep different
code from Quagga to have heterogeneity.

			Ondrej