Re: Follow-up

Re: Follow-up

[Tom Cranbrook]

>> > I am having trouble with the two Xandros distros.  The >> It may be
that Xandros' init program depends on being able to access
>> some piece of hardware that is inaccessible in an unprivileged
>> domain. We had a report that Gentoo's init program has problems too,
>> although that was a long while ago.
>
>I wander if we'd learn anything by starting /sbin/init under
>strace ?
>
>I've never tried this before, but it might be worth a try.
>
>add "init=/linuxrc" on the command line, then create a shell
>script that does "strace /sbin/init". You might have to redirect
>stderr to stdout.
>
>Dropping down an /sbin/init from Debian/RedHat/SuSE might be
>interesting too.
>

Xandros 1.5 is using the plain vanilla sysvinit 2.84-2woody1 deb package,
so there shouldn't be anything wierd there.


Nothing strange in the inittab either.  All standard stuff.


>Ian
>





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RE: Follow-up

[Neugebauer, Rolf]

> -----Original Message-----
> From: xen-devel-admin@lists.sourceforge.net [mailto:xen-devel-
> admin@lists.sourceforge.net] On Behalf Of Tom Cranbrook
> Sent: 27 September 2004 23:39
> To: Mark A. Williamson; xen-devel@lists.sourceforge.net;
> tcranbrook@australia.edu
> Subject: Re: [Xen-devel] Follow-up
> 
> >
> >Performance with VNC was OK when we tried it (like Ian said).  In
fact we
> >turned off compression in order to minimise the overheads, given
> interdomain
> >networking should be wicked-fast.
> >
> >I haven't tried NX on Xen (waiting for a feature-complete FreeNX to
> become
> 
> >readily available), although I very impressed by it's performance
when I
> >tried it internationally via the internet.  It'd be interesting to
see
> how
> 
> >well it performs between domains, particularly in comparison to other
> systems
> >like VNC.  In any case, it still has the advantages of remote
printing +
> >sound + file sharing.
> >
> >Cheers,
> >Mark
> >
> 
> Well, so far NX performs like shit, but I suspect something else may
be
> the
> problem.  I notice on the dom1 run that top reports no swap file at
all.
> If this is true, I would expect bad performance.  Does a vm see the
swap
> partitions?  How are they defined to a vm?
> 

You can give access to any other partition using the config file in the
same way you give access to the root partition. You can't share the same
swap partition amongst different VMs so you have to create one for each
VM. You'd also need to adjust /etc/fstab to whatever partition you
decide to map the physical swap partition.

However, I wouldn't expect performance to be "shit" because of no swap
file. If you'd run out of physical memory (ie need swap) Linux would
complain and not just run slower...so the problem is probably be
elsewhere.

As Ian said, we don't really have experience with NX but have used vnc
with reasonable performance.

Rolf


> 
> 
> 
> 
> 
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Re: Follow-up

[Tom Cranbrook]

>
>Performance with VNC was OK when we tried it (like Ian said).  In fact we 
>turned off compression in order to minimise the overheads, given
interdomain 
>networking should be wicked-fast.
>
>I haven't tried NX on Xen (waiting for a feature-complete FreeNX to become

>readily available), although I very impressed by it's performance when I 
>tried it internationally via the internet.  It'd be interesting to see how

>well it performs between domains, particularly in comparison to other
systems 
>like VNC.  In any case, it still has the advantages of remote printing + 
>sound + file sharing.
>
>Cheers,
>Mark
>

Well, so far NX performs like shit, but I suspect something else may be the
problem.  I notice on the dom1 run that top reports no swap file at all. 
If this is true, I would expect bad performance.  Does a vm see the swap
partitions?  How are they defined to a vm?







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Re: Follow-up

[Mark A. Williamson]

> Well, so far NX performs like shit,

:-(  I found it was snappy talking to a machine in Italy over a mere cable 
modem, so it should work fine.  Out of interest, what NX are you running, 
NoMachine's server / client of FreeNX / kNX?

> but I suspect something else may be the 
> problem.  I notice on the dom1 run that top reports no swap file at all.
> If this is true, I would expect bad performance.  Does a vm see the swap
> partitions?  How are they defined to a vm?

A VM sees it's own swap partitions, if you've configured any.  You need to 
give them a virtual disk to swap to (same procedure as for creating the root 
filesystem device), mkswap on it and add it to their fstab so that they use 
it.

Cheers,
Mark


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Re: Follow-up

[Tom Cranbrook]

 -----
>> Freeing unused kernel memory: 92k freed
>> Warning: unable to open an initial console.
>> ioperm not fully supported - set iopl to 3
>> ------
>
>It looks like you're not getting message sent to /dev/console. 
>
>I don't think you need the extra="console=tty0" -- it should be
>the default. 
>
>Can you post the output of trying to create the domain with the
>'-n' flag to do a dry run and print the final config.
>


Using config file "/etc/xen/xmdefconfig".
(vm
    (name Xserver)
    (memory 64)
    (image
        (linux
            (kernel /boot/vmlinuz-2.6.8.1-xenU)
            (ip 192.168.1.61:1.2.3.4:192.168.1.254:255.255.255.0::eth0:off)
            (root /dev/hdb1)
            (args 4)
        )
    )
    (device (vbd (uname phy:hdb1) (dev hdb1) (mode w)))
    (device (vif (mac aa:00:00:2f:59:44)))
)




>> The console freezes.
>> 
>> The instance shows on the 'xm list'.
>> 
>> xm console xxxx  results in: 
>> Cannot connect to console 12 in domain 1
>
>This might be because the console is still connected on the other
>terminal.
>

after terminating the other frozzed console, I get this on xm console


************ REMOTE CONSOLE: CTRL-] TO QUIT ********
ioperm not fully supported - set iopl to 3

This message is occasionally followed by:

warning: process `update' used the obsolete bdflush system call
Fix your initscripts?






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Follow-up

[Tom Cranbrook]

Thanks for your help.  I have at least one distro version running in both
dom0 and dom1.  (The sshd hadn't been started ...  sheepish grin)

One of my targets is to test the NXserver one a vm domain.  The NX
server-client system supports a full remote KDE session.  This would be a
very intgersting combination. My first run was bumppy.  This does run
through a ssh tunnel. Has anyone tried NX yet?

I am having trouble with the two Xandros distros.  The 2.6.8.1-xenU kernel
boots to this point:

-----
Freeing unused kernel memory: 92k freed
Warning: unable to open an initial console.
ioperm not fully supported - set iopl to 3
------

The console freezes.

The instance shows on the 'xm list'.

xm console xxxx  results in:

Cannot connect to console 12 in domain 1


extra="console=tty0" is set in the config file.


Any suggestions?





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Re: Follow-up

[Ian Pratt]

> Thanks for your help.  I have at least one distro version running in both
> dom0 and dom1.  (The sshd hadn't been started ...  sheepish grin)
> 
> One of my targets is to test the NXserver one a vm domain.  The NX
> server-client system supports a full remote KDE session.  This would be a
> very intgersting combination. My first run was bumppy.  This does run
> through a ssh tunnel. Has anyone tried NX yet?

I haven't tried NX, but there's no reason why it shouldn't work
just fine. It's arguable that since you have plenty of bandwidth
between VMs you'd be better off using a less complex protocol
such as VNC, or just plain X.
 
> I am having trouble with the two Xandros distros.  The 2.6.8.1-xenU kernel
> boots to this point:
> 
> -----
> Freeing unused kernel memory: 92k freed
> Warning: unable to open an initial console.
> ioperm not fully supported - set iopl to 3
> ------

It looks like you're not getting message sent to /dev/console. 

I don't think you need the extra="console=tty0" -- it should be
the default. 

Can you post the output of trying to create the domain with the
'-n' flag to do a dry run and print the final config.

> The console freezes.
> 
> The instance shows on the 'xm list'.
> 
> xm console xxxx  results in: 
> Cannot connect to console 12 in domain 1

This might be because the console is still connected on the other
terminal.

Ian


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Re: Follow-up

[Keir Fraser]

> I am having trouble with the two Xandros distros.  The 2.6.8.1-xenU kernel
> boots to this point:
> 
> -----
> Freeing unused kernel memory: 92k freed
> Warning: unable to open an initial console.
> ioperm not fully supported - set iopl to 3
> ------
> 
> The console freezes.
>
> The instance shows on the 'xm list'.

In what state? Blocked ('b')?

It may be that Xandros' init program depends on being able to access
some piece of hardware that is inaccessible in an unprivileged
domain. We had a report that Gentoo's init program has problems too,
although that was a long while ago.

My approach to debugging this would probably be to download the
Xandros init program's source and add print tracing to it to see where
it fails.

The best fix may then be to submit patches to Xandros. :-)
 
> xm console xxxx  results in:
> Cannot connect to console 12 in domain 1

Did you disconnect the old 'frozen' console session with CTRL-] ??

 -- Keir


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Re: Follow-up

[Ian Pratt]

> > I am having trouble with the two Xandros distros.  The 2.6.8.1-xenU kernel
> > boots to this point:
> > 
> > -----
> > Freeing unused kernel memory: 92k freed
> > Warning: unable to open an initial console.
> > ioperm not fully supported - set iopl to 3
> > ------
> It may be that Xandros' init program depends on being able to access
> some piece of hardware that is inaccessible in an unprivileged
> domain. We had a report that Gentoo's init program has problems too,
> although that was a long while ago.

I wander if we'd learn anything by starting /sbin/init under
strace ?

I've never tried this before, but it might be worth a try.

add "init=/linuxrc" on the command line, then create a shell
script that does "strace /sbin/init". You might have to redirect
stderr to stdout.

Dropping down an /sbin/init from Debian/RedHat/SuSE might be
interesting too.

Ian


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Re: Follow-up

[Mark A. Williamson]

> One of my targets is to test the NXserver one a vm domain.  The NX
> server-client system supports a full remote KDE session.  This would be a
> very intgersting combination. My first run was bumppy.  This does run
> through a ssh tunnel. Has anyone tried NX yet?

Performance with VNC was OK when we tried it (like Ian said).  In fact we 
turned off compression in order to minimise the overheads, given interdomain 
networking should be wicked-fast.

I haven't tried NX on Xen (waiting for a feature-complete FreeNX to become 
readily available), although I very impressed by it's performance when I 
tried it internationally via the internet.  It'd be interesting to see how 
well it performs between domains, particularly in comparison to other systems 
like VNC.  In any case, it still has the advantages of remote printing + 
sound + file sharing.

Cheers,
Mark


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