On Mon, Oct 29, 2012 at 5:42 AM, Mathieu Desnoyers
[off-list ref] wrote:

So defining e.g.:

#include <linux/log2.h>

#define DFR_HASH_BITS  (PAGE_SHIFT - ilog2(BITS_PER_LONG))

would keep the intended behavior in all cases: use one page for the hash
array.

Well, since that wasn't true before either because of the long-time
bug you point out, clearly the page size isn't all that important. I
think it's more important to have small and simple code, and "9" is
certainly that, compared to playing ilog2 games with not-so-obvious
things.

Because there's no reason to believe that '9' is in any way a worse
random number than something page-shift-related, is there? And getting
away from *previous* overly-complicated size calculations that had
been broken because they were too complicated and random, sounds like
a good idea.

            Linus

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