Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752581Ab3G0RfU (ORCPT ); Sat, 27 Jul 2013 13:35:20 -0400 Received: from relay.parallels.com ([195.214.232.42]:42468 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752511Ab3G0RfS (ORCPT ); Sat, 27 Jul 2013 13:35:18 -0400 Message-ID: <51F404D0.6070004@parallels.com> Date: Sat, 27 Jul 2013 21:35:12 +0400 From: Vladimir Davydov User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130704 Icedove/17.0.7 MIME-Version: 1.0 To: Marco Stornelli CC: , , , , , Subject: Re: [PATCH RFC] pram: persistent over-kexec memory file system References: <1374841763-11958-1-git-send-email-vdavydov@parallels.com> <51F3EA2A.3090905@gmail.com> In-Reply-To: <51F3EA2A.3090905@gmail.com> Content-Type: text/plain; charset="ISO-8859-15"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [81.5.110.170] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1620 Lines: 34 On 07/27/2013 07:41 PM, Marco Stornelli wrote: > Il 26/07/2013 14:29, Vladimir Davydov ha scritto: >> Hi, >> >> We want to propose a way to upgrade a kernel on a machine without >> restarting all the user-space services. This is to be done with CRIU >> project, but we need help from the kernel to preserve some data in >> memory while doing kexec. >> >> The key point of our implementation is leaving process memory in-place >> during reboot. This should eliminate most io operations the services >> would produce during initialization. To achieve this, we have >> implemented a pseudo file system that preserves its content during >> kexec. We propose saving CRIU dump files to this file system, kexec'ing >> and then restoring the processes in the newly booted kernel. >> > > http://pramfs.sourceforge.net/ AFAIU it's a bit different thing: PRAMFS as well as pstore, which has already been merged, requires hardware support for over-reboot persistency, so called non-volatile RAM, i.e. RAM which is not directly accessible and so is not used by the kernel. On the contrary, what we'd like to have is preserving usual RAM on kexec. It is possible, because RAM is not reset during kexec. This would allow leaving applications working set as well as filesystem caches in place, speeding the reboot process as a whole and reducing the downtime significantly. Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/