RFC: fp printing speedup patch

[Paolo Carlini]

Paolo Carlini wrote:

> ... hum, now I see that this can be easily explained considering that 
> your performance
> numbers are only for the formatting part not for the complete output 
> (right?). If,
> for instance, we suppose that in current mainline roughly half the 
> total time is spent
> for writing the buffer and half for formatting, everything would be 
> consistent...

... if this is correct (I think so), it also helps putting the whole 
issue in better
perspective, since implies that overall we go from ~6 secs to ~4 (if we 
are "lucky",
that is small numbers) or from ~6 to ~9 (big numbers).

Therefore, the user, which can only see the complete result, may 
experience a 33% speed
improvement or a 50% speed decrease, respectively.

The differences are of course bigger both directions when the low level 
write component
weigh less, that is for faster devices than mine (a vanilla EIDE 80G 
disk) or for
stringbuf.

Paolo.