atropos scheduler params

atropos scheduler params

[Diwaker Gupta]

Hi folks,

I'm trying to use the atropos scheduler with Xen. Couple of questions:

- the scheduling param *has* to be specified at boot time right, or
does Xen allow changing the scheduling scheme at run time??

- xm help atropos gives a very vague message at best, perhaps we could
make it more elaborate:

xm atropos DOM SLICE PERIOD LATENCY XTRATIME

o is DOM the vm ID or the vm NAME (as appearing in xm list)
o SLICE, PERIOD are in nanoseconds I believe?
o XTRATIME has to be 1/0 ?
o some examples with typical values would be great

Finally, I'm passing sched param to Xen at boot time as:
kernel /boot/xen.gz dom0_mem=65536 sched=atropos

But the machine failts to boot with a "CPU 0 is toasted" type of
message! :-O If remove the sched param, things work just fine again.
Any ideas?

Thx
-- 
Diwaker Gupta
http://resolute.ucsd.edu/diwaker


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Re: atropos scheduler params

[Mark A. Williamson]

> - the scheduling param *has* to be specified at boot time right, or
> does Xen allow changing the scheduling scheme at run time??

You can currently only change at boot time.  There aren't any plans to allow 
runtime changes - sysadmins will probably just statically configure the 
scheduler that they prefer for their setup.

> o is DOM the vm ID or the vm NAME (as appearing in xm list)

I expect vm ID will work.  Not sure if the name will also work...

> o some examples with typical values would be great

There's no examples t the moment but there's some more detail on Atropos in 
the user manual and the Sched-HOWTO.

> Finally, I'm passing sched param to Xen at boot time as:
> kernel /boot/xen.gz dom0_mem=65536 sched=atropos
>
> But the machine failts to boot with a "CPU 0 is toasted" type of
> message! :-O If remove the sched param, things work just fine again.
> Any ideas?

That looks right.  The Atropos port is probably broken at the moment as it's 
in the process of being updated to the latest scheduler interface.

HTH,
Mark


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Re: atropos scheduler params

[Diwaker Gupta]

> > But the machine failts to boot with a "CPU 0 is toasted" type of
> > message! :-O If remove the sched param, things work just fine again.
> > Any ideas?
> 
> That looks right.  The Atropos port is probably broken at the moment as it's
> in the process of being updated to the latest scheduler interface.

So this is 2.0 unstable specific, or applies to 1.2 as well? Also, is
someone working on this (I haven't checked the latest nightly, so
apologize if I'm not up-todate) already, otherwise I might want to
look into it.

Thx,
-- 
Diwaker Gupta
http://resolute.ucsd.edu/diwaker


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Re: atropos scheduler params

[Diwaker Gupta]

The atropos scheduler seems to have been fixed in the latest nightly.
So I can reboot and create domains cleanly with this boot line:

kernel /boot/xen.gz dom0_mem=65536 sched=atropos

After creating a domain, xm list reports:
$ xm list
NAME       ID 
domain-0 0 <snip>
vm1           9 <snip>

Now I try to set atropos parameters, but I just can't get them to work:

$ xm atropos vm1 30 100 10 1
Error: atropos invalid argument(s)
$ xm atropos 9 1 30 100 10 1
-- same error --

And lots of other similar combinations, but to no avail. Has anyone
had any success with using atropos? If so, I'd really appreciate some
sample param values.

> There's no examples t the moment but there's some more detail on Atropos in
> the user manual and the Sched-HOWTO.

Both the user manual and the Sched-HOWTO contain essentially the same
text, which gives a brief description of the options.

-- 
Diwaker Gupta
http://resolute.ucsd.edu/diwaker


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