From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: Huang Shijie <shijie8@gmail.com>
Cc: akpm@linux-foundation.org, mel@csn.ul.ie, linux-mm@kvack.org
Subject: Re: [PATCH] mm : kill combined_idx
Date: Mon, 21 Dec 2009 14:31:39 +0900 [thread overview]
Message-ID: <20091221143139.7088a8d3.kamezawa.hiroyu@jp.fujitsu.com> (raw)
In-Reply-To: <1261366347-19232-1-git-send-email-shijie8@gmail.com>
On Mon, 21 Dec 2009 11:32:27 +0800
Huang Shijie <shijie8@gmail.com> wrote:
> In more then half of all the cases, `page' is head of the buddy pair
> {page, buddy} in __free_one_page. That is because the allocation logic
> always picks the head of a chunk, and puts the rest back to the buddy system.
>
> So calculating the combined page is not needed but waste some cycles in
> more then half of all the cases.Just do the calculation when `page' is
> bigger then the `buddy'.
>
> Signed-off-by: Huang Shijie <shijie8@gmail.com>
Hmm...As far as I remember, this code design was for avoiding "if".
Is this compare+jump is better than add+xor ?
Thanks,
-Kame
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next prev parent reply other threads:[~2009-12-21 5:34 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-21 3:32 Huang Shijie
2009-12-21 5:31 ` KAMEZAWA Hiroyuki [this message]
2009-12-21 19:43 ` Mel Gorman
2009-12-22 3:11 ` Huang Shijie
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