From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id DF1F68D003A for ; Thu, 20 Jan 2011 12:44:11 -0500 (EST) Received: by iyj17 with SMTP id 17so821017iyj.14 for ; Thu, 20 Jan 2011 09:44:10 -0800 (PST) MIME-Version: 1.0 In-Reply-To: References: <1295516739-9839-1-git-send-email-pullip.cho@samsung.com> <20110120142844.GA28358@barrios-desktop> Date: Fri, 21 Jan 2011 02:44:09 +0900 Message-ID: Subject: Re: [PATCH] ARM: mm: Regarding section when dealing with meminfo From: Minchan Kim Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org To: KyongHo Cho , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-samsung-soc@vger.kernel.org, Kukjin Kim , Ilho Lee , KeyYoung Park , KyongHo Cho List-ID: Fix linux-arm-kernel address. On Fri, Jan 21, 2011 at 2:43 AM, Minchan Kim wrote: > Restore Cced. > > On Fri, Jan 21, 2011 at 2:24 AM, KyongHo Cho wrote: >> On Thu, Jan 20, 2011 at 11:28 PM, Minchan Kim wrote: >>> On Thu, Jan 20, 2011 at 06:45:39PM +0900, KyongHo Cho wrote: >>>> Sparsemem allows that a bank of memory spans over several adjacent >>>> sections if the start address and the end address of the bank >>>> belong to different sections. >>>> When gathering statictics of physical memory in mem_init() and >>>> show_mem(), this possiblity was not considered. >>> >>> Please write down the result if we doesn't consider this patch. >>> I can understand what happens but for making good description and review, >>> merging easily, it would be better to write down the result without >>> the patch explicitly. >>> >> As we know that each section has its own memmap and >> a contiguous chunk of physical memory that is represented by 'bank' in meminfo >> can be larger than the size of a section. >> "page++" in the current implementation can access invalid memory area. >> The size of the section is 256 MiB in ARM and the number of banks in >> meminfo is 8. >> This means that the maximum size of the physical memory cannot be grow than 2GiB >> to avoid this problem in the current implementation. >> Thus we need to fix the calculation of the last page descriptor in >> terms of sections. >> >> This patch determines the last page descriptor in a memmap with >> min(last_pfn_of_bank, last_pfn_of_current_section) >> If there remains physical memory not consumed, it calculates the last >> page descriptor >> with min(last_pfn_of_bank, last_pfn_of_next_section). >> >>> >>> Hmm.. new ifndef magic makes code readability bad. >>> Couldn't we do it by simple pfn iterator not page and pfn_valid check? >>> >> True. >> We need to consider the implementation again. >> I think the previous implementation gave the importance to the >> efficiency but to the readability. >> > > Please consider readability and consistency with other architectures > if we can do. :) > Thanks. > > -- > Kind regards, > Minchan Kim > -- Kind regards, Minchan Kim -- 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/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org