From: Andrew Morton <akpm@linux-foundation.org>
To: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: mpm@selenic.com, containers@lists.linux-foundation.org,
hpa@zytor.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org,
viro@zeniv.linux.org.uk, linux-api@vger.kernel.org,
mingo@elte.hu, torvalds@linux-foundation.org, tglx@linutronix.de,
xemul@openvz.org
Subject: Re: What can OpenVZ do?
Date: Thu, 12 Feb 2009 14:10:14 -0800 [thread overview]
Message-ID: <20090212141014.2cd3d54d.akpm@linux-foundation.org> (raw)
In-Reply-To: <1234475483.30155.194.camel@nimitz>
On Thu, 12 Feb 2009 13:51:23 -0800
Dave Hansen <dave@linux.vnet.ibm.com> wrote:
> On Thu, 2009-02-12 at 11:42 -0800, Andrew Morton wrote:
> > On Thu, 12 Feb 2009 13:30:35 -0600
> > Matt Mackall <mpm@selenic.com> wrote:
> >
> > > On Thu, 2009-02-12 at 10:11 -0800, Dave Hansen wrote:
> > >
> > > > > - In bullet-point form, what features are missing, and should be added?
> > > >
> > > > * support for more architectures than i386
> > > > * file descriptors:
> > > > * sockets (network, AF_UNIX, etc...)
> > > > * devices files
> > > > * shmfs, hugetlbfs
> > > > * epoll
> > > > * unlinked files
> > >
> > > > * Filesystem state
> > > > * contents of files
> > > > * mount tree for individual processes
> > > > * flock
> > > > * threads and sessions
> > > > * CPU and NUMA affinity
> > > > * sys_remap_file_pages()
> > >
> > > I think the real questions is: where are the dragons hiding? Some of
> > > these are known to be hard. And some of them are critical checkpointing
> > > typical applications. If you have plans or theories for implementing all
> > > of the above, then great. But this list doesn't really give any sense of
> > > whether we should be scared of what lurks behind those doors.
> >
> > How close has OpenVZ come to implementing all of this? I think the
> > implementatation is fairly complete?
>
> I also believe it is "fairly complete". At least able to be used
> practically.
>
> > If so, perhaps that can be used as a guide. Will the planned feature
> > have a similar design? If not, how will it differ? To what extent can
> > we use that implementation as a tool for understanding what this new
> > implementation will look like?
>
> Yes, we can certainly use it as a guide. However, there are some
> barriers to being able to do that:
>
> dave@nimitz:~/kernels/linux-2.6-openvz$ git diff v2.6.27.10... | diffstat | tail -1
> 628 files changed, 59597 insertions(+), 2927 deletions(-)
> dave@nimitz:~/kernels/linux-2.6-openvz$ git diff v2.6.27.10... | wc
> 84887 290855 2308745
>
> Unfortunately, the git tree doesn't have that great of a history. It
> appears that the forward-ports are just applications of huge single
> patches which then get committed into git. This tree has also
> historically contained a bunch of stuff not directly related to
> checkpoint/restart like resource management.
>
> We'd be idiots not to take a hard look at what has been done in OpenVZ.
> But, for the time being, we have absolutely no shortage of things that
> we know are important and know have to be done. Our largest problem is
> not finding things to do, but is our large out-of-tree patch that is
> growing by the day. :(
>
Well we have a chicken-and-eggish thing. The patchset will keep
growing until we understand how much of this:
> dave@nimitz:~/kernels/linux-2.6-openvz$ git diff v2.6.27.10... | diffstat | tail -1
> 628 files changed, 59597 insertions(+), 2927 deletions(-)
we will be committed to if we were to merge the current patchset.
Now, we've gone in blind before - most notably on the
containers/cgroups/namespaces stuff. That hail mary pass worked out
acceptably, I think. Maybe we got lucky. I thought that
net-namespaces in particular would never get there, but it did.
That was a very large and quite long-term-important user-visible
feature.
checkpoint/restart/migration is also a long-term-...-feature. But if
at all possible I do think that we should go into it with our eyes a
little less shut.
Interestingly, there was also prior-art for
containers/cgroups/namespaces within OpenVZ. But we decided up-front
(I think) that the eventual implementation would have little in common
with preceding implementations.
Oh, and I'd disagree with your new Subject:. It's pretty easy to find
out what OpenVZ can do. The more important question here is "how much
of a mess did it make when it did it?"
next prev parent reply other threads:[~2009-02-12 22:11 UTC|newest]
Thread overview: 120+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-27 17:07 [RFC v13][PATCH 00/14] Kernel based checkpoint/restart Oren Laadan
2009-01-27 17:07 ` [RFC v13][PATCH 01/14] Create syscalls: sys_checkpoint, sys_restart Oren Laadan
2009-01-27 17:20 ` Randy Dunlap
2009-01-27 17:08 ` [RFC v13][PATCH 02/14] Checkpoint/restart: initial documentation Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 03/14] Make file_pos_read/write() public Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 04/14] General infrastructure for checkpoint restart Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 05/14] x86 support for checkpoint/restart Oren Laadan
2009-02-24 7:47 ` Nathan Lynch
2009-02-24 16:06 ` Dave Hansen
2009-03-18 7:21 ` Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 06/14] Dump memory address space Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 07/14] Restore " Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 08/14] Infrastructure for shared objects Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 09/14] Dump open file descriptors Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 10/14] Restore open file descriprtors Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 11/14] External checkpoint of a task other than ourself Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 12/14] Track in-kernel when we expect checkpoint/restart to work Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 13/14] Checkpoint multiple processes Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 14/14] Restart " Oren Laadan
2009-02-10 17:05 ` [RFC v13][PATCH 00/14] Kernel based checkpoint/restart Dave Hansen
2009-02-11 22:14 ` Andrew Morton
2009-02-12 9:17 ` Ingo Molnar
2009-02-12 18:11 ` Dave Hansen
2009-02-12 20:48 ` Serge E. Hallyn
2009-02-13 10:20 ` Ingo Molnar
2009-02-12 18:11 ` Dave Hansen
2009-02-12 19:30 ` Matt Mackall
2009-02-12 19:42 ` Andrew Morton
2009-02-12 21:51 ` What can OpenVZ do? Dave Hansen
2009-02-12 22:10 ` Andrew Morton [this message]
2009-02-12 23:04 ` How much of a mess does OpenVZ make? ;) Was: " Dave Hansen
2009-02-26 15:57 ` Alexey Dobriyan
2009-03-10 21:53 ` Alexey Dobriyan
2009-03-10 23:28 ` Serge E. Hallyn
2009-03-11 8:26 ` Cedric Le Goater
2009-03-12 14:53 ` Serge E. Hallyn
2009-03-12 21:01 ` Greg Kurz
2009-03-12 21:21 ` Serge E. Hallyn
2009-03-13 4:29 ` Ying Han
2009-03-13 5:34 ` Sukadev Bhattiprolu
2009-03-13 6:19 ` Ying Han
2009-03-13 17:27 ` Linus Torvalds
2009-03-13 19:02 ` Serge E. Hallyn
2009-03-13 19:35 ` Alexey Dobriyan
2009-03-13 21:01 ` Linus Torvalds
2009-03-13 21:51 ` Dave Hansen
2009-03-13 22:15 ` Oren Laadan
2009-03-14 0:27 ` Eric W. Biederman
2009-03-14 8:12 ` Ingo Molnar
2009-03-16 22:33 ` Kevin Fox
2009-03-19 21:19 ` Eric W. Biederman
2009-03-14 0:20 ` Alexey Dobriyan
2009-03-14 8:25 ` Ingo Molnar
2009-03-16 6:01 ` Oren Laadan
2009-03-13 20:48 ` Mike Waychison
2009-03-13 22:35 ` Oren Laadan
2009-03-18 18:54 ` Mike Waychison
2009-03-18 19:04 ` Oren Laadan
2009-03-13 15:27 ` Cedric Le Goater
2009-03-13 17:11 ` Greg Kurz
2009-03-13 17:37 ` Serge E. Hallyn
2009-03-13 15:47 ` Cedric Le Goater
2009-03-13 16:35 ` Serge E. Hallyn
2009-03-13 16:53 ` Cedric Le Goater
2009-02-26 16:27 ` Alexey Dobriyan
2009-02-26 17:33 ` Ingo Molnar
2009-02-26 18:30 ` Greg Kurz
2009-02-26 22:17 ` Alexey Dobriyan
2009-02-27 9:19 ` Greg Kurz
2009-02-27 10:53 ` Alexey Dobriyan
2009-02-27 14:33 ` Cedric Le Goater
2009-02-27 9:36 ` Cedric Le Goater
2009-02-26 22:31 ` Alexey Dobriyan
2009-02-27 9:03 ` Ingo Molnar
2009-02-27 9:19 ` Andrew Morton
2009-02-27 10:57 ` Alexey Dobriyan
2009-02-27 9:22 ` Andrew Morton
2009-02-27 10:59 ` Alexey Dobriyan
2009-02-27 16:14 ` Dave Hansen
2009-02-27 21:57 ` Alexey Dobriyan
2009-02-27 21:54 ` Dave Hansen
2009-03-01 1:33 ` Alexey Dobriyan
2009-03-01 20:02 ` Serge E. Hallyn
2009-03-01 20:56 ` Alexey Dobriyan
2009-03-01 22:21 ` Serge E. Hallyn
2009-03-03 16:17 ` Cedric Le Goater
2009-03-03 18:28 ` Serge E. Hallyn
2009-02-13 10:53 ` Ingo Molnar
2009-02-16 20:51 ` Dave Hansen
2009-02-17 22:23 ` Ingo Molnar
2009-02-17 22:30 ` Dave Hansen
2009-02-18 0:32 ` Ingo Molnar
2009-02-18 0:40 ` Dave Hansen
2009-02-18 5:11 ` Alexey Dobriyan
2009-02-18 18:16 ` Ingo Molnar
2009-02-18 21:27 ` Dave Hansen
2009-02-18 23:15 ` Ingo Molnar
2009-02-19 19:06 ` Banning checkpoint (was: Re: What can OpenVZ do?) Alexey Dobriyan
2009-02-19 19:11 ` Dave Hansen
2009-02-24 4:47 ` Alexey Dobriyan
2009-02-24 5:11 ` Dave Hansen
2009-02-24 15:43 ` Serge E. Hallyn
2009-02-24 20:09 ` Alexey Dobriyan
2009-02-12 22:17 ` What can OpenVZ do? Alexey Dobriyan
2009-02-13 10:27 ` Ingo Molnar
2009-02-13 11:32 ` Alexey Dobriyan
2009-02-13 11:45 ` Ingo Molnar
2009-02-13 22:28 ` Alexey Dobriyan
2009-03-14 0:04 ` Eric W. Biederman
2009-03-14 0:26 ` Serge E. Hallyn
2009-02-12 22:57 ` [RFC v13][PATCH 00/14] Kernel based checkpoint/restart Dave Hansen
2009-02-12 23:05 ` Matt Mackall
2009-02-12 23:13 ` Dave Hansen
2009-02-13 23:28 ` Andrew Morton
2009-02-14 23:08 ` Ingo Molnar
2009-02-14 23:31 ` Andrew Morton
2009-02-14 23:50 ` Ingo Molnar
2009-02-16 17:37 ` Dave Hansen
2009-03-13 2:45 ` Oren Laadan
2009-03-13 3:57 ` Oren Laadan
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