linux-kernel - Re: [PATCH 0/5] x86 cleanup: convert round

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Date:	Mon, 28 Jul 2008 23:41:27 -0700
From:	"Yinghai Lu" <yhlu.kernel@...il.com>
To:	"Ingo Molnar" <mingo@...e.hu>
Cc:	"Joerg Roedel" <joerg.roedel@....com>, mingo@...hat.com,
	tglx@...utronix.de, linux-kernel@...r.kernel.org,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH 0/5] x86 cleanup: convert round_up() to roundup()

On Sat, Jul 26, 2008 at 6:39 AM, Ingo Molnar <mingo@...e.hu> wrote:
>
> * Joerg Roedel <joerg.roedel@....com> wrote:
>
>> The x86 architecture declares its own round_up macro. But there is a
>> generic one in <linux/kernel.h> which can also be used. This patchset
>> replaces the x86 round_up() macro with the generic roundup() one where
>> possible. The patches have been compile-tested for 32 and 64 bit and
>> boot-tested for 64 bit. If we can fix the other places too we can get
>> rid of the x86 specific round_up() in the future.
>
> applied to tip/x86/cleanups - thanks Joerg!
>
these patches looks like some backward, aka wrong direction.

#define roundup(x, y) ((((x) + ((y) - 1)) / (y)) * (y))

#define round_up(x, y) (((x) + (y) - 1) & ~((y) - 1))
#define round_down(x, y) ((x) & ~((y) - 1))

round_up looks more efficient.

YH
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