From: "KAMEZAWA Hiroyuki" <kamezawa.hiroyu@jp.fujitsu.com>
To: "Hugh Dickins" <hugh.dickins@tiscali.co.uk>
Cc: "KAMEZAWA Hiroyuki" <kamezawa.hiroyu@jp.fujitsu.com>,
"Wu Fengguang" <fengguang.wu@intel.com>,
"Nigel Cunningham" <ncunningham@crca.org.au>,
"LKML" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: No more bits in vm_area_struct's vm_flags.
Date: Tue, 29 Sep 2009 01:14:03 +0900 (JST) [thread overview]
Message-ID: <a0ea21a7cfe313202e2b51510aa5435a.squirrel@webmail-b.css.fujitsu.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0909281637160.25798@sister.anvils>
Hugh Dickins wrote:
> On Mon, 28 Sep 2009, KAMEZAWA Hiroyuki wrote:
>>
>> What I dislike is making vm_flags to be long long ;)
>
> Why?
I'm sorry if my "dislike" sounds too strong.
Every time I see long long in the kernel, my concern is
"do I need spinlock to access this for 32bit arch ? is it safe ?".
(And it makes binary=>disassemble=>C (by eyes) a bit difficult)
Then, I don't like long long personally.
Another reason is some other calls like test_bit() cannot be used against
long long. (even if it's not used _now_)
Maybe vm->vm_flags will not require extra locks because
it can be protected by bigger lock as mmap_sem. Then, please make it
to be long long if its's recommended.
keeping vm_flags to be 32bit may makes vma_merge() ugly.
If so, long long is a choice.
Thanks,
-Kame
> Hugh
>
next prev parent reply other threads:[~2009-09-28 16:14 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-23 4:15 No more bits in vm_area_struct's vm_flags Nigel Cunningham
2009-09-23 20:23 ` Hugh Dickins
2009-09-25 8:30 ` Nigel Cunningham
2009-09-25 11:36 ` Hugh Dickins
2009-09-25 11:47 ` Nigel Cunningham
2009-09-30 12:02 ` Pavel Machek
2009-09-30 13:08 ` swsusp on nommu, was 'Re: No more bits in vm_area_struct's vm_flags.' Johannes Weiner
2009-09-30 16:06 ` Mike Frysinger
2009-09-24 1:05 ` No more bits in vm_area_struct's vm_flags KAMEZAWA Hiroyuki
2009-09-25 8:34 ` Nigel Cunningham
2009-09-25 8:40 ` KAMEZAWA Hiroyuki
2009-09-25 8:48 ` Nigel Cunningham
2009-09-25 21:09 ` Joerg Roedel
2009-09-28 2:45 ` Nigel Cunningham
2009-09-28 3:04 ` KAMEZAWA Hiroyuki
2009-09-28 3:36 ` Wu Fengguang
2009-09-28 3:57 ` KAMEZAWA Hiroyuki
2009-09-28 4:37 ` Nigel Cunningham
2009-09-28 4:51 ` Wu Fengguang
2009-09-28 4:53 ` KAMEZAWA Hiroyuki
2009-09-28 5:22 ` Nigel Cunningham
2009-09-28 5:32 ` KAMEZAWA Hiroyuki
2009-09-28 21:21 ` Hugh Dickins
2009-09-28 21:33 ` Nigel Cunningham
2009-09-28 15:38 ` Hugh Dickins
2009-09-28 16:14 ` KAMEZAWA Hiroyuki [this message]
2009-09-28 21:00 ` Hugh Dickins
2009-09-28 21:22 ` Nigel Cunningham
2009-09-29 1:57 ` KAMEZAWA Hiroyuki
2009-09-29 14:22 ` Christoph Lameter
2009-10-01 10:54 ` Hugh Dickins
2009-10-01 13:47 ` Christoph Lameter
2009-10-01 11:38 ` Hugh Dickins
2009-10-02 0:42 ` KAMEZAWA Hiroyuki
2009-10-02 1:37 ` KAMEZAWA Hiroyuki
2009-10-02 2:39 ` KAMEZAWA Hiroyuki
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