Re: [PATCH] bitops: simplify generic bit finding functions

Thomas Gleixner
2008-04-28T16:00:05Z

On Mon, 28 Apr 2008, Alexander van Heukelum wrote:
> > See patch below. It gives back the 1400 bytes on SPARC64 and other
> > platforms that have no instruction for find bit.
>
> Hi,
>
> I, personally, see this patch as a stopgap measure. The real problem
> is that the generic __ffs is inlined and ends up generating a lot
> of instructions.
>
> Until the generic implementation of __ffs is fixed not to be an
> enormous inline function, this seems to be a reasonable thing
> to do, though it's a shame that the optimization is now default-
> off for architectures with a good implementation of __ffs.

Yup, it hasn't been there before and we explicitely enable it on
x86. If there are other archs which have a good one it's a nobrainer
to enable it.

Thanks,
tglx