Re: [Xen-devel] Configuration parameters get "sometimes" omitted

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

Aha!  Glad that cleared things up.

Possibly we should consider making the behaviour of xm more explicit (e.g. 
requiring a ./ before  choosing a a config from the current directory).

Cheers,
Mark

On Friday 19 October 2007, Juergen Doelle wrote:
> Mark, I am sorry, but with your help I have to give back the "weird problem
> of the week". The
> problem cause is very simple. We were not aware that xm will use the config
> file from the local
> directory. We had one directory with all scripts for cloning, start,
> reboot, and shutdown. And it
> contained the templates for the profiles. After moving them to a different
> location, the real profile
> in /etc/xen/vm were used and it works well.
>
> Thanks for your help,
> Juergen
>
> Juergen Doelle
> Linux End to End Performance Project Lead
> Dept. 3235, Linux on System z System & Performance Evaluation, IBM Lab
> Boeblingen
> http://www.ibm.com/developerworks/linux/linux390/perf
>
> IBM Deutschland Entwicklung GmbH
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> Geschäftsführung: Herbert Kircher
> Sitz der Gesellschaft: Böblingen
> Registergericht: Amtsgericht Stuttgart, HRB 243294
>
>
>
>
>
>
>
>
>              Mark Williamson
>              <mark.williamson@
>              cl.cam.ac.uk>                                              To
>              Sent by: "M.A.            xen-devel@xxxxxxxxxxxxxxxxxxx
>              Williamson"                                                cc
>              <maw48@xxxxxxxxxx         Christian Ehrhardt
>              .ac.uk>                   <ehrhardt@xxxxxxxxxxxxxxxxxx>,
>                                        Juergen Doelle/Germany/IBM@IBMDE
>                                                                    Subject
>              10/18/2007 04:23          Re: [Xen-devel] Configuration
>              AM                        parameters get "sometimes" omitted
>
> > we have the problem that our xen configuration settings are not correctly
> > evaluated when creating a xen guests.
>
> Congratulations - I think you just won my "weird problem of the week"
> award ;-)
>
> > When creating domains with "xm create domainname" the system sometimes
>
> has
>
> > all configuration parameters out of the config files, but sometimes not.
>
> We
>
> > did some tests and saw that the parameters are only certainly used if we
> > specify them via the commandline like "xm create domainname
> > parameter=value,...".
>
> Now that's ... really strange.
>
> What version of Xen is this?  Did you build it from source, or was it
> packaged?  What distro is this?
>
> Are you using any Xend managed domains or are you doing everything by
> config
> files?
>
> > If the parameters are only specified in the configuration files in
> > /etc/xen/ they are parsed and used "sometimes". Another fact we found is
> > that if the "xm create" is called by a script the error occurs very often
> > ~70% of the testcases, while calling the command from a ssh shell
>
> manually
>
> > only fails in ~10% of the testcases. We stripped down the script and it
> > does nothing but calling "xm create" and the normal shell where it works
> > mostly has no .profile/.bashrc/... that change the environment.
>
> Good troubleshooting.  And good analysis...
>
> Are you 100% sure that you don't have another copy of your domain config
> file
> somewhere on the system (e.g. maybe a backup) that might have different
> values in?  Is it possible you're running the commands from different
> directories in each case?
>
> xm will use a config file in ./ if it's there, or it can search /etc/xen.
> I'm
> not sure what the order of precedence is but I'm thinking it might be
> sometimes using one copy and sometimes the other?
>
> Another way to test: try specifying the full path, e.g "xm
> create /etc/xen/lnudb1".  Does this behave consistently?
>
> > Additionally there is some persistent behavior - if it failed once it
>
> will
>
> > fail until the host is rebooted (maybe some config parts are stored and
>
> not
>
> > re-evaluated). I checked xenstore with the script from
> > http://wiki.xensource.com/xenwiki/XenStore and saw that xenstore only has
> > the parameters if a good-case guest is running.
>
> That's strange too...
>
> > An interesting fact is that it does not fail initializing memory or pci
> > passthrough in host or guest - somehow it fails the initial config
>
> parsing.
>
> > You can see below that already the output of XendDomainInfo.create in the
> > log is different in good/bad case.
> >
> > Because of the unstable behavior I expect some kind of race condition
>
> while
>
> > parsing from the files.
>
> This seems very odd.  Although it sounds buggy, it seems to me that others
> would have noticed it if it was common.  Therefore, it suggests that
> there's
> something perculiar to your local system which is provoking this behaviour.
>
> Let us know what you find out, and maybe we can crank through this!
>
> Cheers,
> mark
>
> > The command "xm create lnudb1 pci=04:01.0 memory=2048" works always
> > successful. A "xm create lnudb1" creates only *sometimes* a system with a
> > pci adapter and 2 GB memory. Looking in the /var/log/xend.log reveals a
> > different XendDomainInfo.create statement for good and bad case.
> >
> > (I added the >>> <<< signs to point to the important statement)
> >
> > XendDomainInfo.create(['vm', ['name', 'lnudb1'], ['memory', 2048],
> > ['vcpus', 1], ['on_xend_start', 'ignore'], ['on_xend_stop', 'ignore'],
> > ['image', ['linux', ['kernel', '/etc/xen/vmlinuz-xen'], ['ramdisk',
> > '/etc/xen/initrd-xen'], ['root', '/dev/xvda1'], ['args', 'TERM=xterm
> > selinux=off xencons=tty']]], ['device', ['vbd', ['uname', 'phy:sde5'],
> > ['dev', 'xvda1'], ['mode', 'w']]], ['device', ['vbd', ['uname',
> > 'phy:/dev/hda'], ['dev', 'hdc:cdrom'], ['mode', 'r']]],
> >
> > >>> ['device', ['pci', ['dev', ['domain', '0x0'], ['bus', '0x04'],
>
> ['slot',
>
> > >>> '0x01'], ['func', '0x0']]]], <<<
> >
> > ['device', ['vif', ['bridge', 'xenbr0'], ['mac', '00:16:3e:00:00:10']]],
> > ['device', ['vif', ['bridge', 'xenbr1'], ['mac', '00:16:3e:00:00:31']]],
> > ['device', ['vkbd']], ['device', ['vfb', ['vncunused', '1'], ['type',
> > 'vnc'], ['display', 'localhost:10.0'], ['xauthority',
> > '/root/.Xauthority']]]])
> >
> >
> > The xm create with the profile described above produces following
>
> statement
>
> > XendDomainInfo.create(['vm', ['name', 'lnudb1'], ['memory', 1024],
> > ['vcpus', 1], ['on_xend_start', 'ignore'], ['on_xend_stop', 'ignore'],
> > ['image', ['linux', ['kernel', '/etc/xen/vmlinuz-xen'], ['ramdisk',
> > '/etc/xen/initrd-xen'], ['root', '/dev/xvda1'], ['args', 'TERM=xterm
> > selinux=off xencons=tty']]], ['device', ['vbd', ['uname', 'phy:sde5'],
> > ['dev', 'xvda1'], ['mode', 'w']]], ['device', ['vbd', ['uname',
> > 'phy:/dev/hda'], ['dev', 'hdc:cdrom'], ['mode', 'r']]],
> >
> > >>>  <<<<
> >
> > ['device', ['vif', ['bridge', 'xenbr0'], ['mac', '00:16:3e:00:00:10']]],
> > ['device', ['vif', ['bridge', 'xenbr1'], ['mac', '00:16:3e:00:00:31']]],
> > ['device', ['vkbd']], ['device', ['vfb', ['vncunused', '1'], ['type',
> > 'vnc'], ['display', 'localhost:10.0'], ['xauthority',
> > '/root/.Xauthority']]]])
> >
> > Also note the different values for the memory statement
> >
> > System Description
> > Hardware IBM x3950, 4 Intel Xeon CPUs (dual core) 3.5GHz, 23Gb memory.
> > The operating system is Linux SLES10 SP1, with the following rpms:
> > o xen-kmp-smp-3.1.0_2.6.16.46_0.12-0.1
> > o xen-libs-32bit-3.0.4_13138-0.40
> > o xen-doc-pdf-3.1.0-0.1
> > o kernel-xen-2.6.16.46-0.12
> > o xen-3.1.0-0.1
> > o xen-tools-3.1.0-0.1
> > o xen-doc-html-3.1.0-0.1
> > o xen-libs-3.1.0-0.1
> > o xen-tools-ioemu-3.1.0-0.1
> >
> > the kernel is booted with the parameters
> > pciback.hide=(04:01.0)(04:01.1)(06:01.0)(06:01.1)(08:01.0)(08:01.1)
> > and /etc/modprobe.conf constains the statements
> > install lpfc /sbin/modprobe pciback ; /sbin/modprobe --first-time
> > --ignore-install lpfc options  pciback
> > hide=(04:01.0)(04:01.1)(06:01.0)(06:01.1)(08:01.0)(08:01.1) to hide the
>
> pci
>
> > adapters for the Dom0.
> >
> > The xen profile used is:
> > builder='linux'
> > memory = 2048
> > name = "lnudb1"
> > vcpus = 1
> > vif = [ 'mac=00:16:3e:00:00:10, bridge=xenbr0', 'mac=00:16:3e:00:00:31,
> > bridge=xenbr1' ] disk = [ 'phy:sde5,xvda1,w', 'phy:/dev/hda,hdc:cdrom,r'
>
> ]
>
> > root = "/dev/xvda1"
> > extra = "TERM=xterm selinux=off xencons=tty"
> > vfb=[ "type=vnc,vncunused=1" ]
> > pci= [ '0000:04:01.0' ]
> >
> > The critical parameters are memory and pci, we never saw the issue with
> > e.g. vif's.
> >
> > P.S. It was hard to decide between xen-devel and xen-users by topic for
> > that mail. Eventually I coose xen-devel becasue I'm already member of
>
> this
>
> > list and thereby get also responses that may lack a cc to me. Please
> > redirect if needed.
>
> --
> Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
> Mark: To answer a question with a question: What use is a skateboard?
> Dave: Skateboards have wheels.
> Mark: My wheel has a wheel!



-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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