From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f44.google.com (mail-pa0-f44.google.com [209.85.220.44]) by kanga.kvack.org (Postfix) with ESMTP id C25006B0253 for ; Fri, 9 Oct 2015 05:25:09 -0400 (EDT) Received: by pacex6 with SMTP id ex6so82256714pac.0 for ; Fri, 09 Oct 2015 02:25:09 -0700 (PDT) Received: from mgwym02.jp.fujitsu.com (mgwym02.jp.fujitsu.com. [211.128.242.41]) by mx.google.com with ESMTPS id bi5si1167996pbc.38.2015.10.09.02.25.08 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 09 Oct 2015 02:25:08 -0700 (PDT) Received: from m3050.s.css.fujitsu.com (msm.b.css.fujitsu.com [10.134.21.208]) by yt-mxauth.gw.nic.fujitsu.com (Postfix) with ESMTP id 737FAAC073E for ; Fri, 9 Oct 2015 18:25:05 +0900 (JST) Subject: Re: [PATCH][RFC] mm: Introduce kernelcore=reliable option References: <1444402599-15274-1-git-send-email-izumi.taku@jp.fujitsu.com> <561762DC.3080608@huawei.com> From: Kamezawa Hiroyuki Message-ID: <561787DA.4040809@jp.fujitsu.com> Date: Fri, 9 Oct 2015 18:24:42 +0900 MIME-Version: 1.0 In-Reply-To: <561762DC.3080608@huawei.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Xishi Qiu , Taku Izumi Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, tony.luck@intel.com, mel@csn.ul.ie, akpm@linux-foundation.org, Dave Hansen , Mel Gorman , Ingo Molnar On 2015/10/09 15:46, Xishi Qiu wrote: > On 2015/10/9 22:56, Taku Izumi wrote: > >> Xeon E7 v3 based systems supports Address Range Mirroring >> and UEFI BIOS complied with UEFI spec 2.5 can notify which >> ranges are reliable (mirrored) via EFI memory map. >> Now Linux kernel utilize its information and allocates >> boot time memory from reliable region. >> >> My requirement is: >> - allocate kernel memory from reliable region >> - allocate user memory from non-reliable region >> >> In order to meet my requirement, ZONE_MOVABLE is useful. >> By arranging non-reliable range into ZONE_MOVABLE, >> reliable memory is only used for kernel allocations. >> > > Hi Taku, > > You mean set non-mirrored memory to movable zone, and set > mirrored memory to normal zone, right? So kernel allocations > will use mirrored memory in normal zone, and user allocations > will use non-mirrored memory in movable zone. > > My question is: > 1) do we need to change the fallback function? For *our* requirement, it's not required. But if someone want to prevent user's memory allocation from NORMAL_ZONE, we need some change in zonelist walking. > 2) the mirrored region should locate at the start of normal > zone, right? Precisely, "not-reliable" range of memory are handled by ZONE_MOVABLE. This patch does only that. > > I remember Kame has already suggested this idea. In my opinion, > I still think it's better to add a new migratetype or a new zone, > so both user and kernel could use mirrored memory. Hi, Xishi. I and Izumi-san discussed the implementation much and found using "zone" is better approach. The biggest reason is that zone is a unit of vmscan and all statistics and handling the range of memory for a purpose. We can reuse all vmscan and information codes by making use of zones. Introdcing other structure will be messy. His patch is very simple. For your requirements. I and Izumi-san are discussing following plan. - Add a flag to show the zone is reliable or not, then, mark ZONE_MOVABLE as not-reliable. - Add __GFP_RELIABLE. This will allow alloc_pages() to skip not-reliable zone. - Add madivse() MADV_RELIABLE and modify page fault code's gfp flag with that flag. Thanks, -Kame -- 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