From: Jan Engelhardt
> Sent: 10 June 2022 09:32
>
>
> On Friday 2022-06-10 10:17, David Laight wrote:
> >>
> >> Calling a "printf" style function is already insanely expensive. :-) I
> >> understand that it's not okay blithely to increase runtime resources
> >> simply because it's already slow, but in this case it's worthwhile.
> >
> >Yep, IMHO definitely should be fixed.
> >It is even possible that using "%s" is faster because the printf
> >code doesn't have to scan the string for format effectors.
>
> I see no special handling; the vsnprintf function just loops
> over fmt as usual and I see no special casing of fmt by
> e.g. strcmp(fmt, "%s") == 0 to take a shortcut.
Consider the difference between:
printf("fubar");
and
printf("%s", "fubar");
In the former all of "fubar" is checked for '%'.
In the latter only the length of "fubar" has to be counted.
FWIW the patch description should probably by:
use "%s" when formatting a single string.
(or something to that effect).
David
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