Re: Using qsort(3) in the kernel

["Martin S. Weber" <Ephaeton%gmx.net@localhost>]

On Sun, Nov 16, 2008 at 08:34:38PM +0100, Anders Magnusson wrote:
> Martin S. Weber wrote:
> > On Sun, Nov 16, 2008 at 01:41:34PM -0500, Steven M. Bellovin wrote:
> >> (...)
> >> The kernel stack is limited in size; if the recursion is too deep, it
> >> can exceed that limit.  It's only safe to do recursion if you can (a)
> >> guarantee the maximum depth; and (b) show that for all uses of this
> >> routine, the total stack consumption will be low enough.
> > 
> > Doesn't gcc 4 in the meantime finally support that 70s technique of
> > tail call optimization? Thought I had read about that somewhen.. could
> > be mistaken tho.
> > 
> Yes, gcc does, but that doesn't mean that it can use it for the qsort 
> recursions.
> Not all recursive calls can be optimized away.

Yes that's obvious. Given my background in functional languages I'm just
intrigued by the statement 'recursive is bad, imperative for/while loops are 
good'.

-Martin