From: Nigel Cunningham <ncunningham@linuxmail.org>
To: Pavel Machek <pavel@ucw.cz>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: is_head_of_free_region slowing down swsusp
Date: Fri, 13 Aug 2004 08:42:49 +1000 [thread overview]
Message-ID: <1092350569.24776.22.camel@laptop.cunninghams> (raw)
In-Reply-To: <20040812222348.GA10791@elf.ucw.cz>
Hi Pavel.
On Fri, 2004-08-13 at 08:23, Pavel Machek wrote:
> is_head_of_free_region with count_and_copy_zone results results in
> pretty nasty O(number_of_free_regions^2) behaviour, and some users see
> cpu spending 40 seconds there :-(.
>
> Actually count_and_copy_zone would probably be happy with
> "is_free_page()".
Take a look at my implementation. I do a one-time pass through the slow
path, building a bitmap of free pages. is_head_of_free_region is then
simply a O(1) loop through the bitmap.
Nigel
--
Nigel Cunningham
Christian Reformed Church of Tuggeranong
PO Box 1004, Tuggeranong, ACT 2901
Many today claim to be tolerant. But true tolerance can cope with others
being intolerant.
next prev parent reply other threads:[~2004-08-12 22:49 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-08-12 22:23 Pavel Machek
2004-08-12 22:42 ` Nigel Cunningham [this message]
2004-08-12 23:22 ` Pavel Machek
2004-08-13 5:51 ` Nigel Cunningham
2004-08-13 10:21 ` Pavel Machek
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