Re: [PATCH 00/15] bitops: Change bitmap index from int to unsignedlong

From: Peter Zijlstra
Date: Wed Feb 25 2009 - 10:46:34 EST


On Wed, 2009-02-25 at 08:37 -0700, Matthew Wilcox wrote:
> On Wed, Feb 25, 2009 at 07:54:48AM +0100, Peter Zijlstra wrote:
> > unsigned int wasn't large enough?
>
> Adding one more bit only doubles the maximum size. That buys us, what,
> another eighteen months until we have to change it again? Unsigned long
> seems most sensible to me. Unsigned long long probably isn't worth
> doing -- you'd have to be using one eighth of your address space on a
> single bitmap.

Are you serious? Bitmaps of length 4G-bit (512M-byte) are way past the
sanely allocatable size anyway.

The complaint was that the signed thingy resulted in out of bounds
pointers (apparently unsigned doesn't?)

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