Mike, I'd also be interested in those patches and that code - something like an "xm checkpoint" would be great, which sounds like what you're suggesting or going for in your code there. Thanks, Nick -----Original Message----- From: Mike Sun <msun@gatech.edu> To: Fabian Flägel <fabigant@googlemail.com> Cc: Nick Couchman <Nick.Couchman@seakr.com>, XEN Mailing List <xen-users@lists.xensource.com>, xen-research@lists.xensource.com Subject: Re: [Xen-users] xm save -c Date: Fri, 14 Nov 2008 12:22:38 -0500 Hi Fabian, We're still working to finish the paper first, but I'll certainly cleanup and provide the prototype code after we're done. Thanks, Mike On Fri, Nov 14, 2008 at 4:42 AM, Fabian Flägel <fabigant@googlemail.com> wrote:> Hi Mike, > > i'd like to see your code. :) > > Regards > Fabian > > 2008/11/14 Mike Sun <msun@gatech.edu> >> >> Hi Nick, >> >> > I was wondering if anyone knows of a way to "checkpoint" without pausing >> > the >> > domain? I can't do something like an hourly checkpoint if the domain >> > pauses >> > every hour - the users on the domUs would kill me. Is "seamless >> > checkpointing" something that's being developed, something that can be >> > done >> > another way, or something I should just give up on now? >> >> I've been working on something for my research that probably addresses >> what you're looking for: low latency/downtime checkpointing. There >> are two ways I know this can be done. >> >> You can modify the live-migration mechanism in Xen to save a >> checkpoint instead of migrating to another host. I don't know why >> this hasn't been provided in the xm save tool, but it's a pretty >> simple hack to get working since the xm migrate and xm save codebase >> is basically the same. If you're interested, I can send patches to >> allow you to do that. Then basically on a checkpoint, pre-copying >> would be used to cut the actual time the domU has to be paused. >> >> The other way that I've implemented for my research project is to use >> copy-on-write. I've implemented a prototype and in the middle of >> writing paper for publication. It's not suited for production use, >> but I'd be glad to contribute the code if there's interest. >> >> Mike >> >> _______________________________________________ >> Xen-users mailing list >> Xen-users@lists.xensource.com >> http://lists.xensource.com/xen-users > >This e-mail may contain confidential and privileged material for the sole use of the intended recipient. If this email is not intended for you, or you are not responsible for the delivery of this message to the intended recipient, please note that this message may contain SEAKR Engineering (SEAKR) Privileged/Proprietary Information. In such a case, you are strictly prohibited from downloading, photocopying, distributing or otherwise using this message, its contents or attachments in any way. If you have received this message in error, please notify us immediately by replying to this e-mail and delete the message from your mailbox. Information contained in this message that does not relate to the business of SEAKR is neither endorsed by nor attributable to SEAKR. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
The modification to do a checkpoint using the live migration mechanism
of pre-copying is a trivial one and just something we''re benchmarking
against with our CoW solution. Here''s a patch that changes
''xm save
-c'' to do the checkpoint using the live migration mechanism instead of
the default way. Word of warning: it''s a hack and I haven''t
made the
changes necessary so that the checkpoint file won''t contain the pages
copied during the copy rounds so the checkpoint file will be much
larger than necessary.
I''m not sure why a checkpoint with pre-copying mechanism
hasn''t been
enabled in Xen yet as the necessary code is all there.
Cheers,
Mike
diff -r dca3b5e459e3 tools/python/xen/xend/XendDomain.py
--- a/tools/python/xen/xend/XendDomain.py Wed Sep 17 15:46:05 2008 +0100
+++ b/tools/python/xen/xend/XendDomain.py Fri Nov 14 13:28:39 2008 -0500
@@ -1333,7 +1333,8 @@
oflags |= os.O_LARGEFILE
fd = os.open(dst, oflags)
try:
- XendCheckpoint.save(fd, dominfo, False, False, dst,
+ live = True
+ XendCheckpoint.save(fd, dominfo, False, live, dst,
checkpoint=checkpoint)
except Exception, e:
os.close(fd)
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Whoops, forgot to mention this is a patch for Xen 3.2.2, though I''m sure the changes can be applied to unstable. On Fri, Nov 14, 2008 at 1:35 PM, Mike Sun <msun@gatech.edu> wrote:> The modification to do a checkpoint using the live migration mechanism > of pre-copying is a trivial one and just something we''re benchmarking > against with our CoW solution. Here''s a patch that changes ''xm save > -c'' to do the checkpoint using the live migration mechanism instead of > the default way. Word of warning: it''s a hack and I haven''t made the > changes necessary so that the checkpoint file won''t contain the pages > copied during the copy rounds so the checkpoint file will be much > larger than necessary. > > I''m not sure why a checkpoint with pre-copying mechanism hasn''t been > enabled in Xen yet as the necessary code is all there. > > Cheers, > Mike > > diff -r dca3b5e459e3 tools/python/xen/xend/XendDomain.py > --- a/tools/python/xen/xend/XendDomain.py Wed Sep 17 15:46:05 2008 +0100 > +++ b/tools/python/xen/xend/XendDomain.py Fri Nov 14 13:28:39 2008 -0500 > @@ -1333,7 +1333,8 @@ > oflags |= os.O_LARGEFILE > fd = os.open(dst, oflags) > try: > - XendCheckpoint.save(fd, dominfo, False, False, dst, > + live = True > + XendCheckpoint.save(fd, dominfo, False, live, dst, > checkpoint=checkpoint) > except Exception, e: > os.close(fd)_______________________________________________ Xen-research mailing list Xen-research@lists.xensource.com http://lists.xensource.com/mailman/listinfo/xen-research
On Friday, 14 November 2008 at 13:35, Mike Sun wrote:> The modification to do a checkpoint using the live migration mechanism > of pre-copying is a trivial one and just something we''re benchmarking > against with our CoW solution. Here''s a patch that changes ''xm save > -c'' to do the checkpoint using the live migration mechanism instead of > the default way. Word of warning: it''s a hack and I haven''t made the > changes necessary so that the checkpoint file won''t contain the pages > copied during the copy rounds so the checkpoint file will be much > larger than necessary. > > I''m not sure why a checkpoint with pre-copying mechanism hasn''t been > enabled in Xen yet as the necessary code is all there.I think it''s mostly just that the semantics are a bit weird -- you don''t have a great idea what point in guest time corresponds to the checkpoint you''ll end up with. But we''ve happily that mode here for things like coordinated checkpoints. _______________________________________________ Xen-research mailing list Xen-research@lists.xensource.com http://lists.xensource.com/mailman/listinfo/xen-research