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Date: Sat, 17 Nov 2001 17:24:37 -0800
From: William Lee Irwin III <wli@holomorphy.com>
To: linux@horizon.com
Cc: linux-kernel@vger.kernel.org
Subject: Re: [RFC] tree-based bootmem
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In-Reply-To: <20011118005819.3762.qmail@science.horizon.com>; from linux@horizon.com on Sun, Nov 18, 2001 at 12:58:19AM -0000
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In my bootmem patch, I wrote:
>> #define DIV_DN(x,n) (RND_DN(x,n) / (n))
>> #define DIV_UP(x,n) (RND_UP(x,n) / (n))

On Sun, Nov 18, 2001 at 12:58:19AM -0000, linux@horizon.com wrote:
> Eww.  I realize it's not performance-critical, but how about
> the simpler
> #define DIV_DN(x,n) ((x) / (n))
> #define DIV_UP(x,n) DIV_DN((x)+(n)-1, n)
> 
> There are some alternate definitions of RND_UP available, as well:
> #define RND_UP(x,n) (-RND_DN(-(x),n))
> or
> #define RND_UP(x,n) (~(~(x) | (n)-1))

I hope you don't mind my Cc:'ing lkml in my reply.

These are both excellent points. In the interest of economy of CPU, I
will follow your suggestions in the next installment (and list you in
the changelog =).


Thanks,
Bill
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