From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f181.google.com (mail-pd0-f181.google.com [209.85.192.181]) by kanga.kvack.org (Postfix) with ESMTP id 3055E900016 for ; Thu, 4 Jun 2015 23:19:31 -0400 (EDT) Received: by pdjm12 with SMTP id m12so43755446pdj.3 for ; Thu, 04 Jun 2015 20:19:30 -0700 (PDT) Received: from szxga01-in.huawei.com (szxga01-in.huawei.com. [58.251.152.64]) by mx.google.com with ESMTPS id vp9si8770838pbc.141.2015.06.04.20.19.28 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Thu, 04 Jun 2015 20:19:30 -0700 (PDT) Message-ID: <557113CF.6000905@huawei.com> Date: Fri, 5 Jun 2015 11:13:19 +0800 From: Xishi Qiu MIME-Version: 1.0 Subject: Re: [RFC PATCH 08/12] mm: use mirrorable to switch allocate mirrored memory References: <55704A7E.5030507@huawei.com> <55704C79.5060608@huawei.com> <55709BEA.8030903@intel.com> In-Reply-To: <55709BEA.8030903@intel.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: Andrew Morton , nao.horiguchi@gmail.com, Yinghai Lu , "H. Peter Anvin" , Thomas Gleixner , mingo@elte.hu, Xiexiuqi , Hanjun Guo , "Luck, Tony" , Linux MM , LKML On 2015/6/5 2:41, Dave Hansen wrote: > On 06/04/2015 06:02 AM, Xishi Qiu wrote: >> Add a new interface in path /proc/sys/vm/mirrorable. When set to 1, it means >> we should allocate mirrored memory for both user and kernel processes. > > That's a pretty dangerously short name. :) > Hi Dave, Thanks for your comment. I'm not sure whether we should add this interface for user processes. However some important userspace(e.g. /bin/init, key business like datebase) may be want mirrored memory to improve reliability. If we want this interface, I think the code need more change. Thanks, Xishi Qiu > How would this end up getting used? It seems like it would be dangerous > to use once userspace was very far along. So would the kernel set it to > 1 and then let (early??) userspace set it back to 0? That would let > important userspace like /bin/init get mirrored memory without having to > actually change much in userspace. > > This definitely needs some good documentation. > > Also, if it's insane to turn it back *on*, maybe it should be a one-way > trip to turn off. > > . > -- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932304AbbFEDRQ (ORCPT ); Thu, 4 Jun 2015 23:17:16 -0400 Received: from szxga01-in.huawei.com ([58.251.152.64]:12923 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753518AbbFEDRP (ORCPT ); Thu, 4 Jun 2015 23:17:15 -0400 Message-ID: <557113CF.6000905@huawei.com> Date: Fri, 5 Jun 2015 11:13:19 +0800 From: Xishi Qiu User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:12.0) Gecko/20120428 Thunderbird/12.0.1 MIME-Version: 1.0 To: Dave Hansen CC: Andrew Morton , , Yinghai Lu , "H. Peter Anvin" , "Thomas Gleixner" , , Xiexiuqi , Hanjun Guo , "Luck, Tony" , Linux MM , LKML Subject: Re: [RFC PATCH 08/12] mm: use mirrorable to switch allocate mirrored memory References: <55704A7E.5030507@huawei.com> <55704C79.5060608@huawei.com> <55709BEA.8030903@intel.com> In-Reply-To: <55709BEA.8030903@intel.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.25.179] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2015/6/5 2:41, Dave Hansen wrote: > On 06/04/2015 06:02 AM, Xishi Qiu wrote: >> Add a new interface in path /proc/sys/vm/mirrorable. When set to 1, it means >> we should allocate mirrored memory for both user and kernel processes. > > That's a pretty dangerously short name. :) > Hi Dave, Thanks for your comment. I'm not sure whether we should add this interface for user processes. However some important userspace(e.g. /bin/init, key business like datebase) may be want mirrored memory to improve reliability. If we want this interface, I think the code need more change. Thanks, Xishi Qiu > How would this end up getting used? It seems like it would be dangerous > to use once userspace was very far along. So would the kernel set it to > 1 and then let (early??) userspace set it back to 0? That would let > important userspace like /bin/init get mirrored memory without having to > actually change much in userspace. > > This definitely needs some good documentation. > > Also, if it's insane to turn it back *on*, maybe it should be a one-way > trip to turn off. > > . >