Messages in this thread | | | From | David Howells <> | Subject | Re: get_order() broken ! | Date | Tue, 06 Mar 2007 17:43:16 +0000 |
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Linus Torvalds <torvalds@linux-foundation.org> wrote:
> Yeah, I think the recent get_order() changes to change it to use ilog2() > are just crap. I actually looked at it when it went in, but I assumed that > it had been tested. I don't think it has.
It had, it's just that the testing totally failed to show up the problem; that and I think my userspace testing went wrong because I made the wrong assumptions about what the answer should be.
However, having discussed it with Ben, HPA and David Woodhouse and others I've come up with a patch (sent separately) that should fix it by using:
ilog2((n) - 1) + 1
as the basis for the calculation as this should round up the result. I've encapsulated this as a function called ilog2_up() and fixed the docs to make it cleared how ilog2() and co actually work.
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