From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <45975274.6020909@yahoo.com.au> Date: Sun, 31 Dec 2006 17:02:28 +1100 From: Nick Piggin MIME-Version: 1.0 Subject: Re: Page alignment issue References: <6d6a94c50612270749j77cd53a9mba6280e4129d9d5a@mail.gmail.com> In-Reply-To: <6d6a94c50612270749j77cd53a9mba6280e4129d9d5a@mail.gmail.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Aubrey Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org