From: Andi Kleen <andi@firstfloor.org>
To: Matthew Wilcox <matthew@wil.cx>
Cc: Andi Kleen <andi@firstfloor.org>,
Namhyung Kim <namhyung@gmail.com>, Arnd Bergmann <arnd@arndb.de>,
linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH] introduce ptr_diff()
Date: Thu, 19 Aug 2010 14:58:28 +0200 [thread overview]
Message-ID: <20100819125828.GA6729@basil.fritz.box> (raw)
In-Reply-To: <20100819124017.GI12892@parisc-linux.org>
On Thu, Aug 19, 2010 at 06:40:17AM -0600, Matthew Wilcox wrote:
> On Thu, Aug 19, 2010 at 02:23:09PM +0200, Andi Kleen wrote:
> > IMHO it would be better to simply disable the warning in sparse instead
> > of uglying the code just to work around sparse bogosity. It doesnt' seem
> > to make much sense. A subtraction followed by a shift is not expensive.
>
> What makes you think it's a shift? struct page isn't necessarily a
> power of two in size. The original poster said "allyesconfig" which is
> going to add in KMEMCHECK and WANT_PAGE_DEBUG_FLAGS. I think that makes
> it 76 bytes on x86-32, so sparse is right to warn.
These can be still implemented cheaply. Small constants generally are
The only thing that would be really expensive is division by unknown number.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2010-08-19 12:58 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-19 11:37 [RFC][PATCH] introduce ptr_diff() Namhyung Kim
2010-08-19 11:57 ` Bernd Petrovitsch
2010-08-19 12:03 ` David Howells
2010-08-19 12:23 ` Andi Kleen
2010-08-19 12:40 ` Matthew Wilcox
2010-08-19 12:58 ` Andi Kleen [this message]
2010-08-19 12:58 ` Andi Kleen
2010-08-19 12:48 ` Bernd Petrovitsch
2010-08-19 12:48 ` Bernd Petrovitsch
2010-08-19 12:59 ` Andi Kleen
2010-08-19 13:05 ` Bernd Petrovitsch
2010-08-19 13:39 ` Andi Kleen
2010-08-20 12:12 ` Al Viro
2010-08-19 15:53 ` Namhyung Kim
2010-08-19 16:04 ` Bernd Petrovitsch
2010-08-19 16:12 ` Namhyung Kim
2010-08-20 12:07 ` Al Viro
2010-08-20 12:49 ` Matthew Wilcox
2010-08-20 12:57 ` Andi Kleen
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