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SubjectRe: [PATCH] Reduce the number of expensive division instructions done by _parse_integer()
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On Thu, Feb 9, 2012 at 10:14 PM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:

Ugh, I'm late to the party.

> Because quite frankly, I think we only support bases 8/10/16 in the
> kernel, and if you really have some case where this all is expensive,
> it might be better to simply have three different functions for the
> three bases. That would turn the multiplies into constants too, and
> also simplify the character tests.

base 2 is used to sort of autolimit input to 0/1 characters.

> That said, I can't really see how this could ever be all that hot a
> function. Did you ever see it in a profile, or was this all just from
> looking at the code?

That's why there was no such check from the beginning -- not
performance critical.
We could maintain small table from which digit overflow can happen,
but since this is already committed...

There is CONFIG_TEST_KSTRTOX, does it still passes?


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