From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Minchan Kim <minchan.kim@gmail.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>,
Christoph Lameter <cl@linux-foundation.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Milton Miller <miltonm@bga.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mel@csn.ul.ie>, Johannes Weiner <hannes@cmpxchg.org>,
Kukjin Kim <kgene.kim@samsung.com>
Subject: Re: [PATCH] Tight check of pfn_valid on sparsemem - v4
Date: Sat, 31 Jul 2010 11:38:49 +0100 [thread overview]
Message-ID: <20100731103849.GH23886@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <AANLkTi=DpH=vmUK84KhvOMgP=KL+YxXD0UhiJE+VRJyg@mail.gmail.com>
On Fri, Jul 30, 2010 at 06:32:04PM +0900, Minchan Kim wrote:
> On Fri, Jul 30, 2010 at 5:55 AM, Dave Hansen <dave@linux.vnet.ibm.com> wrote:
> > If you free up parts of the mem_map[] array, how does the buddy
> > allocator still work? I thought we required at 'struct page's to be
> > contiguous and present for at least 2^MAX_ORDER-1 pages in one go.
(Dave, I don't seem to have your mail to reply to.)
What you say is correct, and memory banks as a rule of thumb tend to be
powers of two.
We do have the ability to change MAX_ORDER (which we need to do for some
platforms where there's only 1MB of DMA-able memory.)
However, in the case of two 512KB banks, the buddy allocator won't try
to satisfy a 1MB request as it'll only have two separate 2x512K free
'pages' to deal with, and 0x1M free 'pages'.
next prev parent reply other threads:[~2010-07-31 10:40 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-26 15:46 Minchan Kim
2010-07-26 16:40 ` Christoph Lameter
2010-07-26 22:47 ` Minchan Kim
2010-07-27 5:55 ` miltonm
2010-07-27 6:11 ` Minchan Kim
2010-07-27 8:12 ` Milton Miller
2010-07-27 8:13 ` KAMEZAWA Hiroyuki
2010-07-27 10:01 ` Minchan Kim
2010-07-27 14:34 ` Christoph Lameter
2010-07-27 22:33 ` Minchan Kim
2010-07-28 15:14 ` Christoph Lameter
2010-07-28 15:56 ` Minchan Kim
2010-07-28 17:02 ` Christoph Lameter
2010-07-28 22:57 ` Minchan Kim
2010-07-29 15:46 ` Christoph Lameter
2010-07-29 16:18 ` Minchan Kim
2010-07-29 16:47 ` Christoph Lameter
2010-07-29 17:03 ` Minchan Kim
2010-07-29 17:30 ` Christoph Lameter
2010-07-29 18:33 ` Russell King - ARM Linux
2010-07-29 19:55 ` Christoph Lameter
2010-07-29 21:13 ` Russell King - ARM Linux
2010-07-29 20:55 ` Dave Hansen
2010-07-29 22:14 ` Russell King - ARM Linux
2010-07-29 22:28 ` Christoph Lameter
2010-07-30 0:38 ` Dave Hansen
2010-07-30 9:43 ` Minchan Kim
2010-07-30 12:48 ` Christoph Lameter
2010-07-30 15:43 ` Dave Hansen
2010-07-31 15:30 ` Russell King - ARM Linux
2010-08-02 15:48 ` Christoph Lameter
2010-07-30 9:32 ` Minchan Kim
2010-07-31 10:38 ` Russell King - ARM Linux [this message]
2010-08-11 15:31 ` Dave Hansen
2010-07-27 9:56 ` Minchan Kim
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