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Subject: Re: [OMPI devel] using hnp_always_use_plm
From: Ralph Castain (rhc_at_[hidden])
Date: 2009-12-18 09:45:12


It isn't necessary. The orted already will open and use the local plm if you simply set OMPI_MCA_plm=foo in its environment. The rsh, tm, and slurm plm modules already do this so that they can execute a tree-like spawn (for rsh) and because I needed ssh on the backend nodes to locally launch "slaves" on RoadRunner and other machines.

The required code (already in those modules) is:

    /* enable local launch by the orteds */
    var = mca_base_param_environ_variable("plm", NULL, NULL);
    opal_setenv(var, "rsh", true, &env);
    free(var);

You don't want the orted using the hnp ess module as it will then try to track its own launches and totally forget that it is a remote orted with slightly different responsibilities.

If you need it to execute a different plm on the backend, please let me know - it is a trivial change to allow specification of remote launch agents, and we should do it for them all if we do.

Ralph

On Dec 18, 2009, at 7:43 AM, Damien Guinier wrote:

> Hi Ralph
>
> On Openmpi, I working on a new little feature: hnp_always_use_plm.
> - To create final application , mpirun use on remote "orted via plm: Process lifecycle managment module" or localy "fork()". So the first compute node haven't the same methode than other compute node. Some debug tools(padb ...) and management tools (squeus -s ...) are impacted by this difference.
> To simplify this cluster tools usage, I propose to add the possibility to use "orted via plm" on remote and localy.
>
> I make a patch to add the parameter "OMPI_MCA_ess_hnp_always_use_plm", to use the "plm" module everywhere. On my patch , by default nothing is changed ( no impact).
>
> Can you say to me , if this feature( and the patch) is good ?
>
> thank you
>
> Damien
>
> diff orte/mca/ess/hnp/ess_hnp.h
> --- a/orte/mca/ess/hnp/ess_hnp.h Tue Dec 15 15:31:24 2009 +0100
> +++ b/orte/mca/ess/hnp/ess_hnp.h Tue Dec 15 18:19:18 2009 +0100
> @@ -27,7 +27,7 @@
> int orte_ess_hnp_component_open(void);
> int orte_ess_hnp_component_close(void);
> int orte_ess_hnp_component_query(mca_base_module_t **module, int *priority);
> -
> +extern int mca_ess_hnp_always_use_plm;
>
> ORTE_MODULE_DECLSPEC extern orte_ess_base_component_t mca_ess_hnp_component;
>
> diff orte/mca/ess/hnp/ess_hnp_component.c
> --- a/orte/mca/ess/hnp/ess_hnp_component.c Tue Dec 15 15:31:24 2009 +0100
> +++ b/orte/mca/ess/hnp/ess_hnp_component.c Tue Dec 15 18:19:18 2009 +0100
> @@ -33,6 +33,7 @@
> #include "orte/mca/ess/hnp/ess_hnp.h"
>
> extern orte_ess_base_module_t orte_ess_hnp_module;
> +int mca_ess_hnp_always_use_plm = 0;
>
> /*
> * Instantiate the public struct with all of our public information
> @@ -63,6 +64,10 @@
> int
> orte_ess_hnp_component_open(void)
> {
> + mca_base_param_reg_int(&mca_ess_hnp_component.base_version,
> + "always_use_plm",
> + "Used to force plm on all machine",
> + false,false, mca_ess_hnp_always_use_plm ,&mca_ess_hnp_always_use_plm);
> return ORTE_SUCCESS;
> }
>
> diff orte/mca/ess/hnp/ess_hnp_module.c
> --- a/orte/mca/ess/hnp/ess_hnp_module.c Tue Dec 15 15:31:24 2009 +0100
> +++ b/orte/mca/ess/hnp/ess_hnp_module.c Tue Dec 15 18:19:18 2009 +0100
> @@ -442,9 +442,12 @@
> * node object
> */
> OBJ_RETAIN(proc); /* keep accounting straight */
> + if(mca_ess_hnp_always_use_plm==0)
> + {
> node->daemon = proc;
> node->daemon_launched = true;
> node->state = ORTE_NODE_STATE_UP;
> + }
>
> /* record that the daemon job is running */
> jdata->num_procs = 1;
>