Re: [KVM-AUTOTEST PATCH] A test patch - Boot VMs until one of them becomes unresponsive

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----- "Yolkfull Chow" <yzhou@xxxxxxxxxx> wrote:

> On 06/09/2009 05:44 PM, Michael Goldish wrote:
> > The test looks pretty nicely written. Comments:
> >
> > 1. Consider making all the cloned VMs use image snapshots:
> >
> > curr_vm = vm1.clone()
> > curr_vm.get_params()["extra_params"] += " -snapshot"
> >    
> > I'm not sure it's a good idea to let all VMs use the same disk
> image.
> > Or maybe you shouldn't add -snapshot yourself, but rather do it in
> the config
> > file for the first VM, and then all cloned VMs will have -snapshot
> as well.
> >    
> Yes I use 'image_snapshot = yes' in config file.
> > 2. Consider changing the message
> > " Booting the %dth guest" % num
> > to
> > "Booting guest #%d" % num
> > (because there's no such thing as 2th and 3th)
> >    
> > 3. Consider changing the message
> > "Cannot boot vm anylonger"
> > to
> > "Cannot create VM #%d" % num
> >
> > 4. Why not add curr_vm to vms immediately after cloning it?
> > That way you can kill it in the exception handler later, without
> having
> > to send it a 'quit' if you can't login ('if not curr_vm_session').
> >    
> Yes, good idea.
> > 5. " %dth guest boots up successfully" % num -->  again, 2th and 3th
> make no sense.
> > Also, I wonder why you add those spaces before every info message.
> >
> > 6. "%dth guest's session is not responsive" -->  same
> > (maybe use "Guest session #%d is not responsive" % num)
> >
> > 7. "Shut down the %dth guest" -->  same
> > (maybe "Shutting down guest #%d"? or destroying/killing?)
> >
> > 8. Shouldn't we fail the test when we find an unresponsive session?
> > It seems you just display an error message. You can simply replace
> > logging.error( with raise error.TestFail(.
> >    
> 
> > 9. Consider using a stricter test than just
> vm_session.is_responsive().
> > vm_session.is_responsive() just sends ENTER to the sessions and
> returns
> > True if it gets anything as a result (usually a prompt, or even just
> a
> > newline echoed back). If the session passes this test it is indeed
> > responsive, so it's a decent test, but maybe you can send some
> command
> > (user configurable?) and test for some output. I'm really not sure
> this
> > is important, because I can't imagine a session would respond to a
> newline
> > but not to other commands, but who knows. Maybe you can send the
> first VM
> > a user-specified command when the test begins, remember the output,
> and
> > then send all other VMs the same command and make sure the output is
> the
> > same.
> >    
> maybe use 'info status' and send command 'help' via session to vms and
> compare their output?

I'm not sure I understand. What does 'info status' do? We're talking about
an SSH shell, not the monitor. You can do whatever you like, like 'uname -a',
and 'ls /', but you should leave it up to the user to decide, so he/she
can specify different commands for different guests. Linux commands won't
work under Windows, so Linux and Windows must have different commands in
the config file. In the Linux section, under '- @Linux:' you can add
something like:

stress_boot:
    stress_boot_test_command = uname -a

and under '- @Windows:':

stress_boot:
    stress_boot_test_command = ver && vol

These commands are just naive suggestions. I'm sure someone can think of
much more informative commands.

> > 10. I'm not sure you should use the param "kill_vm_gracefully"
> because that's
> > a postprocessor param (probably not your business). You can just
> call
> > destroy() in the exception handler with gracefully=False, because if
> the VMs
> > are non- responsive, I don't expect them to shutdown nicely with an
> SSH
> > command (that's what gracefully does). Also, we're using -snapshot,
> so
> > there's no reason to shut them down nicely.
> >    
> Yes,  I agree. :)
> > 11. "Total number booted successfully: %d" % (num - 1) -->  why not
> just num?
> > We really have num VMs including the first one.
> > Or you can say: "Total number booted successfully in addition to the
> first one"
> > but that's much longer.
> >    
> Since after the first guest booted, I set num = 1 and then  'num += 1'
> 
> at first in while loop ( for the purpose of getting a new vm ).
> So curr_vm is vm2 ( num is 2) now. If the second vm failed to boot up,
> the num booted successfully should be (num - 1).
> I would use enumerate(vms) that Uri suggested to make number easier to
> count.

OK, I didn't notice that.

> > 12. Consider adding a 'max_vms' (or 'threshold') user param to the
> test. If
> > num reaches 'max_vms', we stop adding VMs and pass the test.
> Otherwise the
> > test will always fail (which is depressing). If
> params.get("threshold") is
> > None or "", or in short -- 'if not params.get("threshold")', disable
> this
> > feature and keep adding VMs forever. The user can enable the feature
> with:
> > max_vms = 50
> > or disable it with:
> > max_vms =
> >    
> This is a good idea for hardware resource limit of host.
> > 13. Why are you catching OSError? If you get OSError it might be a
> framework bug.
> >    
> Since sometimes, vm.create() successfully but failed to ssh-login
> since 
> the running python cannot allocate physical memory (OSError).
> Add max_vms could fix this problem I think.

Do you remember exactly where OSError was thrown? Do you happen to have
a backtrace? (I just want to be very it's not a bug.)

> > 14. At the end of the exception handler you should proably re-raise
> the exception
> > you caught. Otherwise the user won't see the error message. You can
> simply replace
> > 'break' with 'raise' (no parameters), and it should work,
> hopefully.
> >    
> Yes I should if add a 'max_vms'.

I think you should re-raise anyway. Otherwise, what's the point in writing
error messages such as "raise error.TestFail("Cannot boot vm anylonger")"?
I you don't re-raise, the user won't see the messages.

> > I know these are quite a few comments, but they're all rather minor
> and the test
> > is well written in my opinion.
> >    
> Thank you,  I will do modification according to your and Uri's
> comments, 
> and will re-submit it here later. :)
> 
> Thanks and Best Regards,
> Yolkfull
> > Thanks,
> > Michael
> >
> > ----- Original Message -----
> > From: "Yolkfull Chow"<yzhou@xxxxxxxxxx>
> > To:kvm@xxxxxxxxxxxxxxx
> > Cc: "Uri Lublin"<uril@xxxxxxxxxx>
> > Sent: Tuesday, June 9, 2009 11:41:54 AM (GMT+0200) Auto-Detected
> > Subject: [KVM-AUTOTEST PATCH] A test patch - Boot VMs until one of
> them becomes unresponsive
> >
> >
> > Hi,
> >
> > This test will boot VMs until one of them becomes unresponsive, and
> > records the maximum number of VMs successfully started.
> >
> >
> >    
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