From: Alexey Dobriyan <adobriyan@gmail.com>
To: Michal Nazarewicz <mina86@mina86.com>
Cc: Christoph Lameter <cl@linux-foundation.org>,
Pekka Enberg <penberg@kernel.org>, Matt Mackall <mpm@selenic.com>,
Tejun Heo <tj@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Lai Jiangshan <laijs@cn.fujitsu.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [RFC PATCH 1/6] kenrel.h: add ALIGN_OF_LAST_BIT()
Date: Tue, 20 Mar 2012 16:03:24 +0200 [thread overview]
Message-ID: <CACVxJT_UVRjkSK+kieYVpO4R+D-4S2bXaoK-apxMkuFAYsgi_A@mail.gmail.com> (raw)
In-Reply-To: <op.wbgvn00x3l0zgt@mpn-glaptop>
On Tue, Mar 20, 2012 at 2:32 PM, Michal Nazarewicz <mina86@mina86.com> wrote:
> On Tue, 20 Mar 2012 11:21:19 +0100, Lai Jiangshan <laijs@cn.fujitsu.com>
> wrote:
>
>> Get the biggest 2**y that x % (2**y) == 0 for the align value.
>> --- a/include/linux/kernel.h
>> +++ b/include/linux/kernel.h
>> @@ -44,6 +44,8 @@
>> #define PTR_ALIGN(p, a) ((typeof(p))ALIGN((unsigned
>> long)(p), (a)))
>> #define IS_ALIGNED(x, a) (((x) & ((typeof(x))(a) - 1)) ==
>> 0)
>> +#define ALIGN_OF_LAST_BIT(x) ((((x)^((x) - 1))>>1) + 1)
>
>
> Wouldn't ALIGNMENT() be less confusing? After all, that's what this macro is
> calculating, right? Alignment of given address.
Bits do not have alignment because they aren't directly addressable.
Can you hardcode this sequence with comment, because it looks too
special for macro.
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next prev parent reply other threads:[~2012-03-20 14:03 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-20 10:21 [RFC PATCH 0/6] add kmalloc_align() Lai Jiangshan
2012-03-20 10:21 ` [RFC PATCH 1/6] kenrel.h: add ALIGN_OF_LAST_BIT() Lai Jiangshan
2012-03-20 11:32 ` Michal Nazarewicz
2012-03-20 14:03 ` Alexey Dobriyan [this message]
2012-03-20 14:08 ` Christoph Lameter
2012-03-20 14:20 ` Peter Seebach
2012-03-20 10:21 ` [RFC PATCH 2/6] slub: add kmalloc_align() Lai Jiangshan
2012-03-20 14:14 ` Christoph Lameter
2012-03-20 14:21 ` Christoph Lameter
2012-03-20 10:21 ` [RFC PATCH 3/6] slab: " Lai Jiangshan
2012-03-20 10:21 ` [RFC PATCH 4/6] slob: don't couple the header size with the alignment Lai Jiangshan
2012-03-20 10:21 ` [RFC PATCH 5/6] slob: add kmalloc_align() Lai Jiangshan
2012-03-20 10:21 ` [RFC PATCH 6/6] workqueue: use kmalloc_align() instead of hacking Lai Jiangshan
2012-03-20 15:15 ` Christoph Lameter
2012-03-20 15:46 ` Tejun Heo
2012-03-21 3:02 ` Lai Jiangshan
2012-03-21 5:14 ` Tejun Heo
2012-03-21 14:12 ` Patch workqueue: create new slab cache " Christoph Lameter
2012-03-21 14:49 ` Eric Dumazet
2012-03-21 15:03 ` Christoph Lameter
2012-03-21 16:04 ` Eric Dumazet
2012-03-21 17:54 ` Christoph Lameter
2012-03-21 18:05 ` Eric Dumazet
2012-03-21 18:20 ` Christoph Lameter
2012-03-21 16:09 ` Tejun Heo
2012-03-21 17:56 ` Christoph Lameter
2012-03-21 13:45 ` [RFC PATCH 6/6] workqueue: use kmalloc_align() " Christoph Lameter
2012-03-26 2:00 ` Lai Jiangshan
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