[one-users] Help need understanding the scheduler

[Ruben S. Montero]

Hi

The scheduler works as follows, for each pending VM:

1.-  Filters out those hosts without enough capacity to allocate the
VM or that do not meet the REQUIRMENTS. As you imagine, if there are
no REQUIRMENTS only the capacity is checked.

2.- Compute the priority based on the RANK expression. And it sorts
the hosts using the priority

3.- Allocate the VM to that host with higher priority and enough
capacity. Note that the scheduler takes into account the VMs
dispatched previously.

So in this case. I do not really understand why host 2 with priority 1
is after host 1 with priority 0.98. It seems it is a bug.
Could you send as the RANK expression for VM 138 and the outout of
onehost show for hosts 0, 1 and 2. So we can reproduce this error.

Thanks

Ruben

BTW, HID = Host ID, PRIO = priority and HSID no longer makes sense and
should be removed from the log.


On Sat, Oct 31, 2009 at 6:09 AM, Shi Jin <jinzishuai at gmail.com> wrote:
> Hi there,
>
> I am using the default scheduler coming with OpenNebula. According the
> documentation at
> http://www.opennebula.org/doku.php?id=documentation:rel1.4:template,
> I assume the VM are scheduled according to their priority if no
> REQUIREMENT is present. Is this correct?
>
> However, this is part of my sched.log:
> Fri Oct 30 22:44:36 2009 [HOST][D]: Discovered Hosts (enabled): 0 1 2
> Fri Oct 30 22:44:36 2009 [VM][D]: Pending virtual machines : 138
> Fri Oct 30 22:44:36 2009 [SCHED][I]: Select hosts
>        PRI     HID     HSID
>        -------------------
> Virtual Machine: 138
>        0.983083        1
>        1       2
>        0.946115        0
>
>
> Fri Oct 30 22:44:36 2009 [SCHED][I]: Dispatching virtual machine 138 to HID: 1
>
> I am not sure what HID and HSID are but i guess the table lists
> priority and host id. The above case chosen a host with neither the
> highest nor the lower priority number. Is this normal? In my opinion,
> it should have chosen host with HID 2. Maybe I didn't completely
> understand the whole scheduler. Could you please explain a little bit?
> Thanks a lot.
> --
> Shi Jin, Ph.D.
> _______________________________________________
> Users mailing list
> Users at lists.opennebula.org
> http://lists.opennebula.org/listinfo.cgi/users-opennebula.org
>



-- 
+---------------------------------------------------------------+
 Dr. Ruben Santiago Montero
 Associate Professor
 Distributed System Architecture Group (http://dsa-research.org)

 URL:    http://dsa-research.org/doku.php?id=people:ruben
 Weblog: http://blog.dsa-research.org/?author=7

 GridWay, http://www.gridway.org
 OpenNebula, http://www.opennebula.org
+---------------------------------------------------------------+