From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Aubrey <aubreylee@gmail.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: Page alignment issue
Date: Sun, 31 Dec 2006 17:02:28 +1100 [thread overview]
Message-ID: <45975274.6020909@yahoo.com.au> (raw)
In-Reply-To: <6d6a94c50612270749j77cd53a9mba6280e4129d9d5a@mail.gmail.com>
Aubrey wrote:
> As for the buddy system, much of docs mention the physical address of
> the first page frame of a block should be a multiple of the group
> size. For example, the initial address of a 16-page-frame block should
> be 16-page aligned. I happened to encounted an issue that the physical
> addresss pf the block is not 4-page aligned(0x36c9000) while the order
> of the block is 2. I want to know what out of buddy algorithm depend
> on this feature?
I think that's correct. The buddy allocator uses bitwise operations to
find buddy pages and promote free pairs (eg. see __page_find_buddy()
and __find_combined_index()).
--
SUSE Labs, Novell Inc.
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WARNING: multiple messages have this Message-ID (diff)
From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Aubrey <aubreylee@gmail.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: Page alignment issue
Date: Sun, 31 Dec 2006 17:02:28 +1100 [thread overview]
Message-ID: <45975274.6020909@yahoo.com.au> (raw)
In-Reply-To: <6d6a94c50612270749j77cd53a9mba6280e4129d9d5a@mail.gmail.com>
Aubrey wrote:
> As for the buddy system, much of docs mention the physical address of
> the first page frame of a block should be a multiple of the group
> size. For example, the initial address of a 16-page-frame block should
> be 16-page aligned. I happened to encounted an issue that the physical
> addresss pf the block is not 4-page aligned(0x36c9000) while the order
> of the block is 2. I want to know what out of buddy algorithm depend
> on this feature?
I think that's correct. The buddy allocator uses bitwise operations to
find buddy pages and promote free pairs (eg. see __page_find_buddy()
and __find_combined_index()).
--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
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next prev parent reply other threads:[~2006-12-31 6:03 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-12-27 15:49 Page alignment issue Aubrey
2006-12-27 15:49 ` Aubrey
2006-12-28 3:49 ` Aubrey
2006-12-28 3:49 ` Aubrey
2006-12-31 6:02 ` Nick Piggin [this message]
2006-12-31 6:02 ` Nick Piggin
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