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From: Greg Watson (gwatson_at_[hidden])
Date: 2007-01-30 11:24:17


Yes, we need the hostfile information before job execution. We call
setup_job() before a debug job to request a process allocation for
the application being debugged. We use spawn() to launch a non-debug
application. It sounds like I should just leave things the way they
currently are.

I think we've had the discussion about bproc before, but the reason
we still support 1.0.2 is that the registry *is* populated with node
information prior to launch. This was an agreed on feature that
OpenMPI was to provide for PTP. I haven't been able to test 1.2 on a
bproc machine (since I can't get it to work), but it sounds like the
changes removed this functionality. Frankly, this makes OpenMPI less
attractive to us, since we now have to go and get this information
ourselves. My thinking now is that in the future we probably won't
use OpenMPI for anything other than building and launching the
application.

Greg

On Jan 29, 2007, at 6:57 PM, Ralph Castain wrote:

> On further thought, perhaps I should be clearer. If you are saying
> that you
> need to read the hostfile to display the cluster *before* the user
> actually
> submits a job for execution, then fine - go ahead and call rds.query.
>
> What I'm trying to communicate to you is that you need to call
> setup_job
> when you are launching the resulting application. If you want, you
> could do
> the following:
>
> 1. call orte_rds.query(ORTE_JOBID_INVALID) to get your host info.
> Note that
> only a hostfile will be read here - so if you are in (for example)
> a bproc
> environment, you won't get any node info at this point.
>
> 2. when you are ready to launch the app, call orte_rmgr.spawn with an
> attribute list that contains ORTE_RMGR_SPAWN_FLOW with a value of
> ORTE_RMGR_SETUP | ORTE_RMGR_ALLOC | ORTE_RMGR_MAP |
> ORTE_RMGR_SETUP_TRIGS |
> ORTE_RMGR_LAUNCH. This will tell spawn to do everything *except*
> rds.query
> so you avoid re-entering the hostfile info.
>
> Unfortunately, if you want to see node info prior to launch on
> anything
> other than a hostfile, we really don't have a way to do that right
> now. The
> ORTE 2.0 design allows for it, but we haven't implemented that yet -
> probably a few months away.
>
> Hope that helps
> Ralph
>
>
> On 1/29/07 6:45 PM, "Ralph Castain" <rhc_at_[hidden]> wrote:
>
>>
>>
>>
>> On 1/29/07 5:57 PM, "Greg Watson" <gwatson_at_[hidden]> wrote:
>>
>>> Ralph,
>>>
>>> On Jan 29, 2007, at 11:10 AM, Ralph H Castain wrote:
>>>
>>>>
>>>>
>>>>
>>>> On 1/29/07 10:20 AM, "Greg Watson" <gwatson_at_[hidden]> wrote:
>>>>
>>>>>
>>>>> No, we have always called query() first, just after orte_init().
>>>>> Since query() has never required a job id before, this used to
>>>>> work.
>>>>> I think the call was required to kick the SOH into action, but I'm
>>>>> not sure if it was needed for any other purpose.
>>>>
>>>> Query has nothing to do with the SOH - the only time you would
>>>> "need" it
>>>> would be if you are reading a hostfile. Otherwise, it doesn't do
>>>> anything at
>>>> the moment.
>>>>
>>>>
>>>> Not calling setup_job would be risky, in my opinion...
>>>
>>> We've had this discussion before. We *need* to read the hostfile
>>> before calling setup_job() because we have to populate the registry
>>> with node information. If you're saying that this is now no longer
>>> possible, then I'd respectfully ask that this functionality be
>>> restored before you release 1.2. If there is some other way to
>>> achieve this, then please let me know. We've been doing this ever
>>> since 1.0 and in the alpha and beta versions of 1.2.
>>
>> I think you don't understand what setup_job does. Setup_job has four
>> arguments:
>>
>> (a) an array of app_context objects that contain the application
>> to be
>> launched
>>
>> (b) the number of elements in that array
>>
>> (c) a pointer to a location where the jobid for this job is to be
>> returned;
>> and
>>
>> (d) a list of attributes that allows the caller to "fine-tune"
>> behavior
>>
>> With that info, setup_job will:
>>
>> (a) create a new jobid for your application; and
>>
>> (b) store the app_context info in appropriate places in the registry
>>
>> And that is *all* setup_job does - it simply gets a jobid and
>> initializes some
>> important info in the registry. It never looks at node
>> information, nor does
>> it in any way impact node info.
>>
>> Calling rds.query after rmgr.setup_job is how we always do it. In
>> truth, the
>> precise ordering of those two operations is immaterial as they
>> have absolutely
>> nothing in common. However, we always do it in the described order
>> so that
>> rds.query can have a valid jobid. As I said, at the moment
>> rds.query doesn't
>> actually use the jobid, though that will change at some point in
>> the future.
>>
>> Although it isn't *absolutely* necessary, I would still suggest
>> that you call
>> rmgr.setup_job before calling rds.query to ensure that any subsequent
>> operations have all the info they require to function correctly.
>> You can see
>> the progression we use in orte/mca/rmgr/urm/rmgr_urm.c - I believe
>> you will
>> find it helpful to follow that logic.
>>
>> Alternatively, if you want, you can simply repeatedly call
>> orte_rmgr.spawn and
>> use the attributes I built for you to step your way through the
>> standard
>> launch. As you probably recall, I gave you the ability to specify
>> - at a very
>> atomistic level - exactly which steps in the spawn process were to be
>> implemented at each call into rmgr.spawn. You can look at the
>> referenced file
>> to see the attribute for each step in the procedure.
>>
>>
>>>
>>>>
>>>>
>>>>>
>>>>> Are there likely to be further API changes before the release
>>>>> version? We are trying to release PTP, but I think this is
>>>>> impossible
>>>>> until your API's stabilize.
>>>>
>>>> None planned, other than what I mentioned above. If you want to
>>>> support Open
>>>> MPI 1.2, you may need a slight phase shift, though, so you can see
>>>> the final
>>>> release.
>>>
>>> Please explain "phase shift".
>>>
>>> Greg
>>> _______________________________________________
>>> devel mailing list
>>> devel_at_[hidden]
>>> http://www.open-mpi.org/mailman/listinfo.cgi/devel
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