[PATCH] ipsum_calc_block: Optimize size and speed

[Joakim Tjernlund]

Martin Mares <mj at ucw.cz> wrote on 2010/04/23 23:02:29:
>
> Hello!
>
> > How did you come to the conclusion the the current code was better than
> > the previous version? Seems like "hand waving" to me.
>
> Did I claim anywhere that the old code is better?  I only pointed out

You did when you commited it and I asked twice how you came to that conlusion.
Pretty much all recent tests shows otherwise.

> the lack of arguments about the new code being better, which is a reason
> to stay with the old, tested code.
>
> > I told told you I had benched the "add carry in C" before and it wasn't
> > any better(worse actually).
>
> Actually, back in the ages when I wrote the old checksum function, I have
> checked that it performs better than a trivial implementation, and now you
> claim otherwise, so I naturally want to see new data which show that modern
> hardware behaves differently.
>
> > Santiago benched it too and it was better
> > or just as good as before. Only the MIPS had a regression.
>
> If I recall his results correctly, he has performed three tests:
>
> In the 1st one, your code was 20% faster.
> In the 2nd one, it was of the same speed.
> In the 3rd one, it was 20% slower.
>
> Maybe I wear different glasses from yours, but I clearly see that on average,
> there is no improvement.

You have ignored my tests which also show an improvement.

>
> > So what now? what more proof do you need?
>
> First of all, I want at least a rudimentary proof that IT MATTERS AT ALL.
> We are spending lots of time talking about a minor (20%) speedup in a small
> chunk of code, without having any clue about how often it gets called and what
> fraction of the total time is really spent there.

20% is a lot and I not going to bench it any further. if you are
not happy with the results so far, nothing I can do will change that.