From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Hansen Subject: Re: [RFC v7][PATCH 2/9] General infrastructure for checkpoint restart Date: Tue, 21 Oct 2008 20:02:43 -0700 Message-ID: <1224644563.1848.232.camel@nimitz> References: <1224481237-4892-1-git-send-email-orenl@cs.columbia.edu> <1224481237-4892-3-git-send-email-orenl@cs.columbia.edu> <20081021124130.a002e838.akpm@linux-foundation.org> <20081021202410.GA10423@us.ibm.com> <48FE82DF.6030005@cs.columbia.edu> <20081022025513.GA7504@caradoc.them.org> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20081022025513.GA7504-FDxGpBj5bhMn2ysHARXsoQ@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Daniel Jacobowitz Cc: Oren Laadan , linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, mingo-X9Un+BFzKDI@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org, hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org, Andrew Morton , torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org List-Id: linux-api@vger.kernel.org On Tue, 2008-10-21 at 22:55 -0400, Daniel Jacobowitz wrote: > I haven't been following - but why this whole container restriction? > Checkpoint/restart of individual processes is very useful too. > There are issues with e.g. IPC, but I'm not convinced they're > substantially different than the issues already present for a > container. Containers provide isolation. Once you have isolation, you have a discrete set of resources which you can checkpoint/restart. Let's say you have a process you want to checkpoint. If it uses a completely discrete IPC namespace, you *know* that nothing else depends on those IPC ids. We don't even have to worry about who might have been using them and when. Also think about pids. Without containers, how can you guarantee a restarted process that it can regain the same pid? -- Dave -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752306AbYJVDC5 (ORCPT ); Tue, 21 Oct 2008 23:02:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751548AbYJVDCs (ORCPT ); Tue, 21 Oct 2008 23:02:48 -0400 Received: from e32.co.us.ibm.com ([32.97.110.150]:44803 "EHLO e32.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751014AbYJVDCr (ORCPT ); Tue, 21 Oct 2008 23:02:47 -0400 Subject: Re: [RFC v7][PATCH 2/9] General infrastructure for checkpoint restart From: Dave Hansen To: Daniel Jacobowitz Cc: Oren Laadan , linux-api@vger.kernel.org, containers@lists.linux-foundation.org, mingo@elte.hu, linux-kernel@vger.kernel.org, linux-mm@kvack.org, viro@zeniv.linux.org.uk, hpa@zytor.com, Andrew Morton , torvalds@linux-foundation.org, tglx@linutronix.de In-Reply-To: <20081022025513.GA7504@caradoc.them.org> References: <1224481237-4892-1-git-send-email-orenl@cs.columbia.edu> <1224481237-4892-3-git-send-email-orenl@cs.columbia.edu> <20081021124130.a002e838.akpm@linux-foundation.org> <20081021202410.GA10423@us.ibm.com> <48FE82DF.6030005@cs.columbia.edu> <20081022025513.GA7504@caradoc.them.org> Content-Type: text/plain Date: Tue, 21 Oct 2008 20:02:43 -0700 Message-Id: <1224644563.1848.232.camel@nimitz> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2008-10-21 at 22:55 -0400, Daniel Jacobowitz wrote: > I haven't been following - but why this whole container restriction? > Checkpoint/restart of individual processes is very useful too. > There are issues with e.g. IPC, but I'm not convinced they're > substantially different than the issues already present for a > container. Containers provide isolation. Once you have isolation, you have a discrete set of resources which you can checkpoint/restart. Let's say you have a process you want to checkpoint. If it uses a completely discrete IPC namespace, you *know* that nothing else depends on those IPC ids. We don't even have to worry about who might have been using them and when. Also think about pids. Without containers, how can you guarantee a restarted process that it can regain the same pid? -- Dave From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by e34.co.us.ibm.com (8.13.8/8.13.8) with ESMTP id m9M32jjW014206 for ; Tue, 21 Oct 2008 23:02:46 -0400 Received: from d03av03.boulder.ibm.com (d03av03.boulder.ibm.com [9.17.195.169]) by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v9.1) with ESMTP id m9M32juI145964 for ; Tue, 21 Oct 2008 21:02:45 -0600 Received: from d03av03.boulder.ibm.com (loopback [127.0.0.1]) by d03av03.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m9M32jWN030462 for ; Tue, 21 Oct 2008 21:02:45 -0600 Subject: Re: [RFC v7][PATCH 2/9] General infrastructure for checkpoint restart From: Dave Hansen In-Reply-To: <20081022025513.GA7504@caradoc.them.org> References: <1224481237-4892-1-git-send-email-orenl@cs.columbia.edu> <1224481237-4892-3-git-send-email-orenl@cs.columbia.edu> <20081021124130.a002e838.akpm@linux-foundation.org> <20081021202410.GA10423@us.ibm.com> <48FE82DF.6030005@cs.columbia.edu> <20081022025513.GA7504@caradoc.them.org> Content-Type: text/plain Date: Tue, 21 Oct 2008 20:02:43 -0700 Message-Id: <1224644563.1848.232.camel@nimitz> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Daniel Jacobowitz Cc: Oren Laadan , linux-api@vger.kernel.org, containers@lists.linux-foundation.org, mingo@elte.hu, linux-kernel@vger.kernel.org, linux-mm@kvack.org, viro@zeniv.linux.org.uk, hpa@zytor.com, Andrew Morton , torvalds@linux-foundation.org, tglx@linutronix.de List-ID: On Tue, 2008-10-21 at 22:55 -0400, Daniel Jacobowitz wrote: > I haven't been following - but why this whole container restriction? > Checkpoint/restart of individual processes is very useful too. > There are issues with e.g. IPC, but I'm not convinced they're > substantially different than the issues already present for a > container. Containers provide isolation. Once you have isolation, you have a discrete set of resources which you can checkpoint/restart. Let's say you have a process you want to checkpoint. If it uses a completely discrete IPC namespace, you *know* that nothing else depends on those IPC ids. We don't even have to worry about who might have been using them and when. Also think about pids. Without containers, how can you guarantee a restarted process that it can regain the same pid? -- Dave -- 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