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SubjectRe: [patch 1/13] Qsort
On Sun, 23 Jan 2005, Andi Kleen wrote:

> > How about a shell sort? if the data is mostly sorted shell sort beats
> > qsort lots of times, and since the data sets are often small in-kernel,
> > shell sorts O(n^2) behaviour won't harm it too much, shell sort is also
> > faster if the data is already completely sorted. Shell sort is certainly
> > not the simplest algorithm around, but I think (without having done any
> > tests) that it would probably do pretty well for in-kernel use... Then
> > again, I've known to be wrong :)
>
> I like shell sort for small data sets too. And I agree it would be
> appropiate for the kernel.
>
Even with large data sets that are mostly unsorted shell sorts performance
is close to qsort, and there's an optimization that gives it O(n^(3/2))
runtime (IIRC), and another nice property is that it's iterative so it
doesn't eat up stack space (as oposed to qsort which is recursive and eats
stack like ****)...
Yeah, I think shell sort would be good for the kernel.


--
Jesper Juhl



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