From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx197.postini.com [74.125.245.197]) by kanga.kvack.org (Postfix) with SMTP id 0E9C46B0070 for ; Thu, 5 Jul 2012 21:00:11 -0400 (EDT) Received: by vcbfl10 with SMTP id fl10so7255306vcb.14 for ; Thu, 05 Jul 2012 18:00:10 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20120704092006.GH14154@suse.de> References: <1341047274-5616-1-git-send-email-jiang.liu@huawei.com> <20120703140705.af23d4d3.akpm@linux-foundation.org> <4FF39F0E.4070300@huawei.com> <20120704092006.GH14154@suse.de> Date: Thu, 5 Jul 2012 18:00:09 -0700 Message-ID: Subject: Re: [PATCH] mm: setup pageblock_order before it's used by sparse From: Yinghai Lu Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman , Benjamin Herrenschmidt Cc: Jiang Liu , Andrew Morton , Tony Luck , Xishi Qiu , KAMEZAWA Hiroyuki , KOSAKI Motohiro , David Rientjes , Minchan Kim , Keping Chen , linux-mm@kvack.org, stable@vger.kernel.org, linux-kernel@vger.kernel.org, Jiang Liu On Wed, Jul 4, 2012 at 2:20 AM, Mel Gorman wrote: > On Wed, Jul 04, 2012 at 09:40:30AM +0800, Jiang Liu wrote: >> > It's a bit ugly calling set_pageblock_order() from both sparse_init() >> > and from free_area_init_core(). Can we find a single place from which >> > to call it? It looks like here: >> > >> > --- a/init/main.c~a >> > +++ a/init/main.c >> > @@ -514,6 +514,7 @@ asmlinkage void __init start_kernel(void >> > __stop___param - __start___param, >> > -1, -1, &unknown_bootoption); >> > >> > + set_pageblock_order(); >> > jump_label_init(); >> > >> > /* >> > >> > would do the trick? >> > >> > (free_area_init_core is __paging_init and set_pageblock_order() is >> > __init. I'm too lazy to work out if that's wrong) >> >> Hi Andrew, >> Thanks for you comments. Yes, this's an issue. >> And we are trying to find a way to setup pageorder_block as >> early as possible. Yinghai has suggested a good way for IA64, >> but we still need help from PPC experts because PPC has the >> same issue and I'm not familiar with PPC architecture. >> We will submit another patch once we find an acceptable >> solution here. > > I think it's overkill to try and do this on a per-architecture basis unless > you are aware of a case where the per-architecture code cares about the > value of pageblock_order. I find it implausible that the architecture > needs to know the value very early in boot as pageblock_order is part of > the arch-independent memory model. Andrew's suggestion seems reasonable > to me once the section mess is figured out. cma, dma_continugous_reserve is referring pageblock_order very early too. just after init_memory_mapping() for x86's setup_arch. so set pageblock_order early looks like my -v2 patch is right way. current question: need to powerpc guys to check who to set that early. Thanks Yinghai -- 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