From: "H. Peter Anvin" <hpa@zytor.com>
To: David Howells <dhowells@redhat.com>
Cc: torvalds@osdl.org, akpm@osdl.org, benh@kernel.crashing.org,
linux-kernel@vger.kernel.org, johannes@sipsolutions.net
Subject: Re: [PATCH] Fix get_order() [try #2]
Date: Tue, 06 Mar 2007 10:51:27 -0800 [thread overview]
Message-ID: <45EDB82F.8030803@zytor.com> (raw)
In-Reply-To: <11476.1173206866@redhat.com>
David Howells wrote:
> H. Peter Anvin <hpa@zytor.com> wrote:
>
>> Why not just make it ((n) < 1 ? 0 : ...) and make it well-defined for
>> n == 0?
>
> Because log2(0) is -INF or mathematically undefined or something isn't it?
Yes, but it's a *rounding up* function. In this case, it makes sense to
round up 0 to 1. This is, in fact, a common way to handle requests for
zero-byte allocation in order to be able to return a unique address for
each one, so it's not a spurious thing.
-hpa
next prev parent reply other threads:[~2007-03-06 18:53 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-06 18:34 [PATCH] Fix get_order() [try #2] David Howells
2007-03-06 18:37 ` H. Peter Anvin
2007-03-06 18:41 ` David Howells
2007-03-06 18:39 ` H. Peter Anvin
2007-03-06 18:47 ` David Howells
2007-03-06 18:51 ` H. Peter Anvin [this message]
2007-03-06 19:42 ` Alexey Dobriyan
2007-03-06 20:01 ` David Howells
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