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Re: [Xen-devel] [PATCH][RFC] making "xm dump-core" paralell

To: Ian Pratt <Ian.Pratt@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH][RFC] making "xm dump-core" paralell
From: "Daniel P. Berrange" <berrange@xxxxxxxxxx>
Date: Fri, 28 Sep 2007 21:07:46 +0100
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Akio Takebe <takebe_akio@xxxxxxxxxxxxxx>, John Levon <levon@xxxxxxxxxxxxxxxxx>, Rikiya Ayukawa <ayukawa@xxxxxxxxxxxxxxxxxxx>, Rikiya Ayukawa <ayukawa.rikiya@xxxxxxxxxxxxxxxxxx>, SUZUKI Kazuhiro <kaz@xxxxxxxxxxxxxx>
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On Fri, Sep 28, 2007 at 08:53:01PM +0100, Ian Pratt wrote:
> > > xm save/restore also fork+exec. I think it's the same reason.
> > > Is that right, Keir?
> > 
> > My understanding is that the only reason we have separate binaries for
> > that is because in the past save/restore was unstable, and had a
> > tendency to crash xend.
> I can't see much downside to having a separate process. It makes it
> easier to ionice the IO etc.

Well the fact that XenD has to parse the STDOUT from these processes applying
a regex of '^ERROR:' in an attempt to try and catch errors is one fairly 
large downside.  Combine that with the incredibly complex interactions
between XenD and QEMU, again with tricky error reporting and the result is
a pretty hard thing to debug.

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