openmpi/ompi/mca/bml/r2/bml_r2.c

/*
 * Copyright (c) 2004-2007 The Trustees of Indiana University and Indiana
 *                         University Research and Technology
 *                         Corporation.  All rights reserved.
 * Copyright (c) 2004-2007 The University of Tennessee and The University
 *                         of Tennessee Research Foundation.  All rights
 *                         reserved.
 * Copyright (c) 2004-2005 High Performance Computing Center Stuttgart, 
 *                         University of Stuttgart.  All rights reserved.
 * Copyright (c) 2004-2006 The Regents of the University of California.
 *                         All rights reserved.
 * Copyright (c) 2007      Los Alamos National Security, LLC.  All rights
 *                         reserved. 
 * Copyright (c) 2008      Cisco Systems, Inc.  All rights reserved.
 * $COPYRIGHT$
 * 
 * Additional copyrights may follow
 * 
 * $HEADER$
 */

#include "ompi_config.h"

#include <stdlib.h>
#include <string.h>

#include "opal/util/argv.h"
#include "orte/util/show_help.h"
#include "ompi/class/ompi_bitmap.h"
#include "ompi/mca/bml/bml.h"
#include "ompi/mca/bml/base/base.h"
#include "ompi/mca/btl/btl.h"
#include "ompi/mca/btl/base/base.h"
#include "ompi/mca/bml/base/bml_base_btl.h" 
#include "bml_r2.h"
#include "orte/util/name_fns.h"
#include "ompi/proc/proc.h"

extern mca_bml_base_component_t mca_bml_r2_component; 

mca_bml_r2_module_t mca_bml_r2 = {
    {
        &mca_bml_r2_component, 
        0, /* eager limit */ 
        0, /* min send size */ 
        0, /* max send size */ 
        0, /* min rdma size */ 
        0, /* max rdma size */ 
        mca_bml_r2_add_procs,
        mca_bml_r2_del_procs,
        mca_bml_r2_add_btl,
        mca_bml_r2_del_btl,
        mca_bml_r2_del_proc_btl,
        mca_bml_r2_register, 
        mca_bml_r2_register_error,
        mca_bml_r2_finalize, 
        mca_bml_r2_progress,
        mca_bml_r2_ft_event
    }
    
};

/* Names of all the BTL components that this BML is aware of */
static char *btl_names = NULL;


static inline unsigned int bml_base_log2(unsigned long val) {
    unsigned int count = 0;
    while(val > 0) {
        val = val >> 1;
        count++;
    }
    return count > 0 ? count-1: 0;
}

static int btl_exclusivity_compare(const void* arg1, const void* arg2)
{
    mca_btl_base_module_t* btl1 = *(struct mca_btl_base_module_t**)arg1;
    mca_btl_base_module_t* btl2 = *(struct mca_btl_base_module_t**)arg2;
    if( btl1->btl_exclusivity > btl2->btl_exclusivity ) {
        return -1;
    } else if (btl1->btl_exclusivity == btl2->btl_exclusivity ) {
        return 0;
    } else {
        return 1;
    }
}

int mca_bml_r2_progress( void )
{ 
    int i, count = 0;

    /*
     * Progress each of the BTL modules
     */
    for( i = 0; i < (int)mca_bml_r2.num_btl_progress; i++) {
        int rc = mca_bml_r2.btl_progress[i]();
        if(rc > 0) {
            count += rc;
        }
    }
    return count;
}


static int mca_bml_r2_add_btls( void )
{
    int i;
    opal_list_t *btls = NULL; 
    mca_btl_base_selected_module_t* selected_btl;
    size_t num_btls = 0; 
    char **btl_names_argv = NULL;
    
    if(true == mca_bml_r2.btls_added) {
        return OMPI_SUCCESS; 
    }

    /* build an array of r2s and r2 modules */
    btls = &mca_btl_base_modules_initialized;
    num_btls = opal_list_get_size(btls);

    mca_bml_r2.num_btl_modules = 0;
    mca_bml_r2.num_btl_progress = 0;
   
    mca_bml_r2.btl_modules = (mca_btl_base_module_t **)malloc(sizeof(mca_btl_base_module_t*) * num_btls);
    mca_bml_r2.btl_progress = (mca_btl_base_component_progress_fn_t*)malloc(sizeof(mca_btl_base_component_progress_fn_t) * num_btls);
   
    if (NULL == mca_bml_r2.btl_modules || 
        NULL == mca_bml_r2.btl_progress) {
        return OMPI_ERR_OUT_OF_RESOURCE;
    }

    for(selected_btl =  (mca_btl_base_selected_module_t*)opal_list_get_first(btls);
        selected_btl != (mca_btl_base_selected_module_t*)opal_list_get_end(btls);
        selected_btl =  (mca_btl_base_selected_module_t*)opal_list_get_next(selected_btl)) {
        mca_btl_base_module_t *btl = selected_btl->btl_module;
        mca_bml_r2.btl_modules[mca_bml_r2.num_btl_modules++] = btl;
        for (i = 0; NULL != btl_names_argv && NULL != btl_names_argv[i]; ++i) {
            if (0 == 
                strcmp(btl_names_argv[i],
                       btl->btl_component->btl_version.mca_component_name)) {
                break;
            }
        }
        if (NULL == btl_names_argv || NULL == btl_names_argv[i]) {
            opal_argv_append_nosize(&btl_names_argv, 
                                    btl->btl_component->btl_version.mca_component_name);
        }
    }
    if (NULL != btl_names_argv) {
        btl_names = opal_argv_join(btl_names_argv, ' ');
        opal_argv_free(btl_names_argv);
    } else {
        btl_names = strdup("no devices available");
    }

    /* sort r2 list by exclusivity */
    qsort(mca_bml_r2.btl_modules, 
          mca_bml_r2.num_btl_modules, 
          sizeof(struct mca_btl_base_module_t*), 
          btl_exclusivity_compare);
    mca_bml_r2.btls_added = true; 
    return OMPI_SUCCESS;
}

static int btl_bandwidth_compare(const void *v1, const void *v2)
{
    mca_bml_base_btl_t *b1 = (mca_bml_base_btl_t*)v1,
                       *b2 = (mca_bml_base_btl_t*)v2;

    return b2->btl->btl_bandwidth - b1->btl->btl_bandwidth;
}

/*
 *   For each proc setup a datastructure that indicates the BTLs
 *   that can be used to reach the destination.
 *
 */

int mca_bml_r2_add_procs( size_t nprocs, 
                          struct ompi_proc_t** procs, 
                          struct mca_bml_base_endpoint_t** bml_endpoints, 
                          struct ompi_bitmap_t* reachable )
{
    size_t p, p_index, n_new_procs = 0;
    struct mca_btl_base_endpoint_t ** btl_endpoints = NULL;  
    struct ompi_proc_t** new_procs = NULL; 
    struct ompi_proc_t *unreach_proc = NULL;
    int rc, ret = OMPI_SUCCESS;

    if(0 == nprocs) {
        return OMPI_SUCCESS;
    }
    
    if(OMPI_SUCCESS != (rc = mca_bml_r2_add_btls()) ) {
        return rc;
    }
    
    new_procs = (struct ompi_proc_t **) 
        malloc(nprocs * sizeof(struct ompi_proc_t *)); 
    if (NULL == new_procs ) {
        return OMPI_ERR_OUT_OF_RESOURCE;
    }
    memset(bml_endpoints, 0, nprocs * sizeof(struct mca_bml_base_endpoint_t*));

    for(p_index = 0; p_index < nprocs; p_index++) { 
        struct ompi_proc_t* proc;
        proc = procs[p_index]; 
        OBJ_RETAIN(proc); 
        
        if(NULL !=  proc->proc_bml) { 
            bml_endpoints[p_index] = 
                (mca_bml_base_endpoint_t*) proc->proc_bml; 
        } else { 
            new_procs[n_new_procs++] = proc; 
        }
    }

    if ( 0 == n_new_procs ) {
        return OMPI_SUCCESS;
    }
    
    procs = new_procs; 
    nprocs = n_new_procs; 
    
    /* attempt to add all procs to each r2 */
    btl_endpoints = (struct mca_btl_base_endpoint_t **) 
        malloc(nprocs * sizeof(struct mca_btl_base_endpoint_t*)); 
    if (NULL == btl_endpoints) {
        return OMPI_ERR_OUT_OF_RESOURCE;
    }

    for(p_index = 0; p_index < mca_bml_r2.num_btl_modules; p_index++) {
        mca_btl_base_module_t* btl = mca_bml_r2.btl_modules[p_index];
        int btl_inuse = 0;

        /* if the r2 can reach the destination proc it sets the
         * corresponding bit (proc index) in the reachable bitmap
         * and can return addressing information for each proc
         * that is passed back to the r2 on data transfer calls
         */
        ompi_bitmap_clear_all_bits(reachable);
        memset(btl_endpoints, 0, nprocs *sizeof(struct mca_btl_base_endpoint_t*)); 

        rc = btl->btl_add_procs(btl, n_new_procs, new_procs, btl_endpoints, reachable);
        if(OMPI_SUCCESS != rc) {
            /* This BTL has troubles adding the nodes. Let's continue maybe some other BTL
             * can take care of this task.
             */
            continue;
        }

        /* for each proc that is reachable - add the endpoint to the bml_endpoints array(s) */
        for(p=0; p<n_new_procs; p++) {
            if(ompi_bitmap_is_set_bit(reachable, p)) {
                ompi_proc_t *proc = new_procs[p]; 
                mca_bml_base_endpoint_t * bml_endpoint = (mca_bml_base_endpoint_t*) proc->proc_bml; 
                mca_bml_base_btl_t* bml_btl; 
                size_t size;
                
                if(NULL == bml_endpoint) { 
                    /* allocate bml specific proc data */
                    bml_endpoint = OBJ_NEW(mca_bml_base_endpoint_t);
                    if (NULL == bml_endpoint) {
                        opal_output(0, "mca_bml_r2_add_procs: unable to allocate resources");
                        free(btl_endpoints);
                        return OMPI_ERR_OUT_OF_RESOURCE;
                    }
                    
                    /* preallocate space in array for max number of r2s */
                    mca_bml_base_btl_array_reserve(&bml_endpoint->btl_eager, mca_bml_r2.num_btl_modules);
                    mca_bml_base_btl_array_reserve(&bml_endpoint->btl_send,  mca_bml_r2.num_btl_modules);
                    mca_bml_base_btl_array_reserve(&bml_endpoint->btl_rdma,  mca_bml_r2.num_btl_modules);
                    bml_endpoint->btl_max_send_size = -1;
                    bml_endpoint->btl_proc = proc;
                    proc->proc_bml = bml_endpoint; 
                 
                    bml_endpoint->btl_flags_and = 0;
                    bml_endpoint->btl_flags_or = 0;
                }

                bml_endpoints[p] =(mca_bml_base_endpoint_t*)  proc->proc_bml; 

                /* dont allow an additional BTL with a lower exclusivity ranking */
                size = mca_bml_base_btl_array_get_size(&bml_endpoint->btl_send);
                if(size > 0) {
                    bml_btl = mca_bml_base_btl_array_get_index(&bml_endpoint->btl_send, size-1);
                    /* skip this btl if the exclusivity is less than the previous */
                    if(bml_btl->btl->btl_exclusivity > btl->btl_exclusivity) {
                        if(btl_endpoints[p] != NULL) {
                            btl->btl_del_procs(btl, 1, &proc, &btl_endpoints[p]);
                        }
                        continue;
                    }
                }

                /* cache the endpoint on the proc */
                bml_btl = mca_bml_base_btl_array_insert(&bml_endpoint->btl_send);
                bml_btl->btl = btl;
                bml_btl->btl_eager_limit = btl->btl_eager_limit;
                bml_btl->btl_rndv_eager_limit = btl->btl_rndv_eager_limit;
                bml_btl->btl_max_send_size = btl->btl_max_send_size;
                bml_btl->btl_rdma_pipeline_send_length =
                    btl->btl_rdma_pipeline_send_length;
                bml_btl->btl_rdma_pipeline_frag_size =
                    btl->btl_rdma_pipeline_frag_size;
                bml_btl->btl_min_rdma_pipeline_size =
                    btl->btl_min_rdma_pipeline_size;
                bml_btl->btl_endpoint = btl_endpoints[p];
                bml_btl->btl_weight = 0;
                bml_btl->btl_alloc = btl->btl_alloc;
                bml_btl->btl_free = btl->btl_free;
                bml_btl->btl_prepare_src = btl->btl_prepare_src;
                bml_btl->btl_prepare_dst = btl->btl_prepare_dst;
                bml_btl->btl_send = btl->btl_send;
                bml_btl->btl_sendi = btl->btl_sendi;
                bml_btl->btl_flags = btl->btl_flags; 
                bml_btl->btl_put = btl->btl_put;
                if( (bml_btl->btl_flags & MCA_BTL_FLAGS_PUT) && (NULL == bml_btl->btl_put) ) {
                    opal_output(0, "mca_bml_r2_add_procs: The PUT flag is specified for"
                                " the %s BTL without any PUT function attached. Disard the flag !",
                                bml_btl->btl->btl_component->btl_version.mca_component_name);
                    bml_btl->btl_flags ^= MCA_BTL_FLAGS_PUT;
                }
                bml_btl->btl_get = btl->btl_get;
                if( (bml_btl->btl_flags & MCA_BTL_FLAGS_GET) && (NULL == bml_btl->btl_get) ) {
                    opal_output(0, "mca_bml_r2_add_procs: The GET flag is specified for"
                                " the %s BTL without any GET function attached. Disard the flag !",
                                bml_btl->btl->btl_component->btl_version.mca_component_name);
                    bml_btl->btl_flags ^= MCA_BTL_FLAGS_GET;
                }
                bml_btl->btl_mpool = btl->btl_mpool;
                if( (bml_btl->btl_flags & (MCA_BTL_FLAGS_PUT | MCA_BTL_FLAGS_GET | MCA_BTL_FLAGS_SEND)) == 0 ) {
                    /**
                     * If no protocol specified, we have 2 choices: we ignore the BTL
                     * as we don't know which protocl to use, or we suppose that all
                     * BTLs support the send protocol. 
                     */
                    bml_btl->btl_flags |= MCA_BTL_FLAGS_SEND;
                }
                /**
                 * calculate the bitwise OR and AND of the btl flags 
                 */
                bml_endpoint->btl_flags_or |= bml_btl->btl_flags;
                bml_endpoint->btl_flags_and &= bml_btl->btl_flags;
                /* This BTL is in use, allow the progress registration */
                btl_inuse++;
            }
        }
        if(btl_inuse > 0 && NULL != btl->btl_component->btl_progress) {
            size_t p;
            bool found = false;
            for(p=0; p<mca_bml_r2.num_btl_progress; p++) {
                if(mca_bml_r2.btl_progress[p] == btl->btl_component->btl_progress) {
                    found = true;
                    break;
                }
            }
            if(found == false) {
                mca_bml_r2.btl_progress[mca_bml_r2.num_btl_progress] = 
                    btl->btl_component->btl_progress;
                mca_bml_r2.num_btl_progress++;
            }
        }
    }
    free(btl_endpoints);

    /* iterate back through procs and compute metrics for registered r2s */
    for(p=0; p<n_new_procs; p++) {
        ompi_proc_t *proc = new_procs[p];
        mca_bml_base_endpoint_t* bml_endpoint = (mca_bml_base_endpoint_t*) proc->proc_bml;
        double total_bandwidth = 0;
        uint32_t latency = 0xffffffff;
        size_t n_index;
        size_t n_size;

        /* skip over procs w/ no btl's registered */
        if(NULL == bml_endpoint) {
            continue;
        }

        /* (1) determine the total bandwidth available across all btls
         *     note that we need to do this here, as we may already have btls configured
         * (2) determine the highest priority ranking for latency
         * (3) compute the maximum amount of bytes that can be send without any
         *     weighting. Once the left over is smaller than this number we will
         *     start using the weight to compute the correct amount.
         */
        n_size = mca_bml_base_btl_array_get_size(&bml_endpoint->btl_send); 
        
        /* sort BTLs in descending order according to bandwidth value */
        qsort(bml_endpoint->btl_send.bml_btls, n_size,
                sizeof(mca_bml_base_btl_t), btl_bandwidth_compare);

        bml_endpoint->bml_max_send_length = 0;
        bml_endpoint->bml_max_rdma_length = 0;
        bml_endpoint->btl_rdma_index = 0;
        for(n_index = 0; n_index < n_size; n_index++) {
            mca_bml_base_btl_t* bml_btl = 
                mca_bml_base_btl_array_get_index(&bml_endpoint->btl_send, n_index);
            mca_btl_base_module_t* btl = bml_btl->btl;
            total_bandwidth += bml_btl->btl->btl_bandwidth;
            if(btl->btl_latency < latency) {
                latency = btl->btl_latency;
            }
            bml_endpoint->bml_max_send_length += bml_btl->btl->btl_bandwidth;
        }
        
        /* (1) set the weight of each btl as a percentage of overall bandwidth
         * (2) copy all btl instances at the highest priority ranking into the
         *     list of btls used for first fragments
         */
        for(n_index = 0; n_index < n_size; n_index++) {
            mca_bml_base_btl_t* bml_btl = 
                mca_bml_base_btl_array_get_index(&bml_endpoint->btl_send, n_index);
            mca_btl_base_module_t *btl = bml_btl->btl;

            /* compute weighting factor for this r2 */
            if(btl->btl_bandwidth > 0) {
                bml_btl->btl_weight = btl->btl_bandwidth / total_bandwidth;
            } else {
                bml_btl->btl_weight = 1.0 / n_size;
            }

            /* check to see if this r2 is already in the array of r2s 
             * used for first fragments - if not add it.
             */
            if(btl->btl_latency == latency) {
                mca_bml_base_btl_t* bml_btl_new = 
                    mca_bml_base_btl_array_insert(&bml_endpoint->btl_eager);
                *bml_btl_new = *bml_btl;
            }

            /* set endpoint max send size as min of available btls */
            if(bml_endpoint->btl_max_send_size > btl->btl_max_send_size)
               bml_endpoint->btl_max_send_size = btl->btl_max_send_size;

            /* check flags - is rdma prefered */
            if ((btl->btl_flags & (MCA_BTL_FLAGS_PUT|MCA_BTL_FLAGS_GET)) &&
                !((proc->proc_arch != ompi_proc_local_proc->proc_arch) &&
                  (0 == (btl->btl_flags & MCA_BTL_FLAGS_HETEROGENEOUS_RDMA)))) {
                mca_bml_base_btl_t* bml_btl_rdma = mca_bml_base_btl_array_insert(&bml_endpoint->btl_rdma);
                *bml_btl_rdma = *bml_btl;
                if(bml_endpoint->btl_pipeline_send_length <
                        bml_btl_rdma->btl_rdma_pipeline_send_length) {
                    bml_endpoint->btl_pipeline_send_length =
                        bml_btl_rdma->btl_rdma_pipeline_send_length;
                }
                if(bml_endpoint->btl_send_limit < bml_btl_rdma->btl_min_rdma_pipeline_size) {
                    bml_endpoint->btl_send_limit = bml_btl_rdma->btl_min_rdma_pipeline_size;
                }
            }
        }
    }

    /* see if we have a connection to everyone else */
    for(p=0; p<n_new_procs; p++) {
        ompi_proc_t *proc = new_procs[p];

        if (NULL == proc->proc_bml) {
            if (NULL == unreach_proc) {
                unreach_proc = proc;
            }
            ret = OMPI_ERR_UNREACH;
        }
    }

    if (mca_bml_r2.show_unreach_errors && 
        OMPI_ERR_UNREACH == ret) {
        orte_show_help("help-mca-bml-r2",
                       "unreachable proc",
                       true, 
                       (ompi_proc_local_proc->proc_hostname ?
                        ompi_proc_local_proc->proc_hostname :
                        ORTE_NAME_PRINT(&(ompi_proc_local_proc->proc_name))),
                       (unreach_proc->proc_hostname ? 
                        unreach_proc->proc_hostname :
                        ORTE_NAME_PRINT(&(unreach_proc->proc_name))),
                       btl_names);
    }

    free(new_procs); 

    return ret;
}

/*
 * iterate through each proc and notify any PTLs associated
 * with the proc that it is/has gone away
 */

int mca_bml_r2_del_procs(size_t nprocs, 
                         struct ompi_proc_t** procs) 
{
    size_t p;
    int rc;
    struct ompi_proc_t** del_procs = (struct ompi_proc_t**) 
        malloc(nprocs * sizeof(struct ompi_proc_t*)); 
    size_t n_del_procs = 0; 

    if (NULL == del_procs) {
        return OMPI_ERR_OUT_OF_RESOURCE;
    }

    for(p =0; p < nprocs; p++) { 
        ompi_proc_t *proc = procs[p]; 
        if(((opal_object_t*)proc)->obj_reference_count == 1) { 
            del_procs[n_del_procs++] = proc; 
        }
    }
    
    for(p = 0; p < n_del_procs; p++) {
        ompi_proc_t *proc = del_procs[p];
        mca_bml_base_endpoint_t* bml_endpoint = (mca_bml_base_endpoint_t*) proc->proc_bml;
        size_t f_index, f_size;
        size_t n_index, n_size;
 
        /* notify each ptl that the proc is going away */
        f_size = mca_bml_base_btl_array_get_size(&bml_endpoint->btl_eager);
        for(f_index = 0; f_index < f_size; f_index++) {
            mca_bml_base_btl_t* bml_btl = mca_bml_base_btl_array_get_index(&bml_endpoint->btl_eager, f_index);
            mca_btl_base_module_t* btl = bml_btl->btl;
            
            rc = btl->btl_del_procs(btl,1,&proc,&bml_btl->btl_endpoint);
            if(OMPI_SUCCESS != rc) {
                return rc;
            }

            /* remove this from next array so that we dont call it twice w/ 
             * the same address pointer
             */
            n_size = mca_bml_base_btl_array_get_size(&bml_endpoint->btl_eager);
            for(n_index = 0; n_index < n_size; n_index++) {
                mca_bml_base_btl_t* search_bml_btl = mca_bml_base_btl_array_get_index(&bml_endpoint->btl_send, n_index);
                if(search_bml_btl->btl == btl) {
                    memset(search_bml_btl, 0, sizeof(mca_bml_base_btl_t));
                    break;
                }
            }
        }

        /* notify each r2 that was not in the array of r2s for first fragments */
        n_size = mca_bml_base_btl_array_get_size(&bml_endpoint->btl_send);
        for(n_index = 0; n_index < n_size; n_index++) {
            mca_bml_base_btl_t* bml_btl = mca_bml_base_btl_array_get_index(&bml_endpoint->btl_eager, n_index);
            mca_btl_base_module_t* btl = bml_btl->btl;
            if (btl != 0) {
                rc = btl->btl_del_procs(btl,1,&proc,&bml_btl->btl_endpoint);
                if(OMPI_SUCCESS != rc) {
                    return rc;
                }
            }
        }
        
        OBJ_RELEASE(proc); 
        /* do any required cleanup */
        OBJ_RELEASE(bml_endpoint);
        
    }
    return OMPI_SUCCESS;
}

int mca_bml_r2_finalize( void ) { 
    ompi_proc_t** procs;
    size_t p, num_procs;
    opal_list_item_t* w_item;

    if (NULL != btl_names) {
        free(btl_names);
        btl_names = NULL;
    }

    /* Similar to mca_bml_r2_del_btl ... */
    procs = ompi_proc_all(&num_procs);
    if(NULL == procs)
        goto CLEANUP;

    for (w_item =  opal_list_get_first(&mca_btl_base_modules_initialized);
         w_item != opal_list_get_end(&mca_btl_base_modules_initialized);
         w_item =  opal_list_get_next(w_item)) {
        mca_btl_base_selected_module_t *sm = (mca_btl_base_selected_module_t *) w_item;

        /* dont use this btl for any peers */
        for(p=0; p<num_procs; p++) {
            ompi_proc_t* proc = procs[p];
            mca_bml_r2_del_proc_btl(proc, sm->btl_module);
        }
    }

 CLEANUP:
    mca_bml_r2.num_btl_modules = 0;
    mca_bml_r2.num_btl_progress = 0;

    if( NULL != mca_bml_r2.btl_modules) {
        free( mca_bml_r2.btl_modules);
    }
    if( NULL != mca_bml_r2.btl_progress ) {
        free( mca_bml_r2.btl_progress);
    }

    mca_btl_base_close();

    return OMPI_SUCCESS;
} 


/*
 *  (1) Remove btl from each bml endpoint
 *  (2) Remove btl from the global list
 */

int mca_bml_r2_del_btl(mca_btl_base_module_t* btl)
{
    ompi_proc_t** procs;
    size_t i, j, m, p, num_procs;
    opal_list_item_t* item;
    mca_btl_base_module_t** modules;
    mca_btl_base_component_progress_fn_t * btl_progress_new; 
    bool found = false;
    
    procs = ompi_proc_all(&num_procs);
    if(NULL == procs)
        return OMPI_SUCCESS;
    
    if(opal_list_get_size(&mca_btl_base_modules_initialized) == 2){ 
        opal_output(0, "only one BTL left, can't failover");
        goto CLEANUP; 
    }
    
    /* dont use this btl for any peers */
    for(p=0; p<num_procs; p++) {
        ompi_proc_t* proc = procs[p];
        mca_bml_r2_del_proc_btl(proc, btl);
    }

    /* remove from the btl list */
    for (item =  opal_list_get_first(&mca_btl_base_modules_initialized);
         item != opal_list_get_end(&mca_btl_base_modules_initialized);
         item =  opal_list_get_next(item)) {
        mca_btl_base_selected_module_t *sm = (mca_btl_base_selected_module_t *) item;
        if(sm->btl_module == btl) {
            opal_list_remove_item(&mca_btl_base_modules_initialized, item);
            free(sm);
            found = true;
            break;
        }
    }
    if(!found) {
        /* doesn't even exist */
        goto CLEANUP;
    }
    /* remove from bml list */
    modules = (mca_btl_base_module_t**)malloc(sizeof(mca_btl_base_module_t*) * mca_bml_r2.num_btl_modules-1);
    for(i=0,m=0; i<mca_bml_r2.num_btl_modules; i++) {
        if(mca_bml_r2.btl_modules[i] != btl) {
            modules[m++] = mca_bml_r2.btl_modules[i];
        }
    }
    free(mca_bml_r2.btl_modules);
    mca_bml_r2.btl_modules = modules;
    mca_bml_r2.num_btl_modules = m;

        
    if(btl->btl_component->btl_progress) { 
        /* figure out which progress functions to keep */
        /* don't need to keep any if this is the last one.. */
        if(mca_bml_r2.num_btl_progress > 1) { 
            btl_progress_new = (mca_btl_base_component_progress_fn_t*)
                malloc(sizeof(mca_btl_base_component_progress_fn_t) * 
                       (mca_bml_r2.num_btl_progress - 1));
            j = 0;
            for(i = 0; i < mca_bml_r2.num_btl_progress; i++) { 
                if(btl->btl_component->btl_progress != mca_bml_r2.btl_progress[i]) { 
                    btl_progress_new[j] = mca_bml_r2.btl_progress[i];
                    j++;
                }
            }
            free(mca_bml_r2.btl_progress);
            mca_bml_r2.btl_progress = btl_progress_new;
        }
        mca_bml_r2.num_btl_progress--; 
    }
    /* cleanup */
    btl->btl_finalize(btl);
CLEANUP:
    free(procs);
    return OMPI_SUCCESS;
}

int mca_bml_r2_del_proc_btl(ompi_proc_t* proc, mca_btl_base_module_t* btl)
{
    mca_bml_base_endpoint_t* ep = (mca_bml_base_endpoint_t*)proc->proc_bml;
    double total_bandwidth = 0;
    size_t b;

    if(NULL == ep)
        return OMPI_SUCCESS;

    /* remove btl from eager list */
    mca_bml_base_btl_array_remove(&ep->btl_eager, btl);
    
    /* remove btl from send list */ 
    if(mca_bml_base_btl_array_remove(&ep->btl_send, btl)) { 
    
        /* compute total_bandwidth and 
           reset max_send_size to the min of all btl's */
        total_bandwidth = 0;
        for(b=0; b< mca_bml_base_btl_array_get_size(&ep->btl_send); b++) {
            mca_bml_base_btl_t* bml_btl = mca_bml_base_btl_array_get_index(&ep->btl_send, b);
            total_bandwidth += bml_btl->btl->btl_bandwidth;
            if (bml_btl->btl_max_send_size < ep->btl_max_send_size) {
                ep->btl_max_send_size = bml_btl->btl->btl_max_send_size;
            }
        }
        
        /* compute weighting factor for this btl */
        for(b=0; b< mca_bml_base_btl_array_get_size(&ep->btl_send); b++) {
            mca_bml_base_btl_t* bml_btl = mca_bml_base_btl_array_get_index(&ep->btl_send, b);
            if(bml_btl->btl->btl_bandwidth > 0) {
                bml_btl->btl_weight = bml_btl->btl->btl_bandwidth / total_bandwidth;
            } else {
                bml_btl->btl_weight = 1.0 / mca_bml_base_btl_array_get_size(&ep->btl_send);
            }
        }
    }

    /* remove btl from RDMA list */
    if(mca_bml_base_btl_array_remove(&ep->btl_rdma, btl)) { 
        
        /* computer total bandwidth */
        total_bandwidth = 0;
        for(b=0; b< mca_bml_base_btl_array_get_size(&ep->btl_rdma); b++) {
            mca_bml_base_btl_t* bml_btl = mca_bml_base_btl_array_get_index(&ep->btl_rdma, b);
            /* update aggregate endpoint info */
            total_bandwidth += bml_btl->btl->btl_bandwidth;
            if (ep->btl_pipeline_send_length <
                    bml_btl->btl_rdma_pipeline_send_length) {
                ep->btl_pipeline_send_length =
                    bml_btl->btl_rdma_pipeline_send_length;
            }
            if (ep->btl_send_limit < bml_btl->btl_min_rdma_pipeline_size) {
                ep->btl_send_limit = bml_btl->btl_min_rdma_pipeline_size;
            }
        }
        
        /* compute weighting factor for this btl */
        for(b=0; b< mca_bml_base_btl_array_get_size(&ep->btl_rdma); b++) {
            mca_bml_base_btl_t* bml_btl = mca_bml_base_btl_array_get_index(&ep->btl_rdma, b);
            if(bml_btl->btl->btl_bandwidth > 0) {
                bml_btl->btl_weight = bml_btl->btl->btl_bandwidth / total_bandwidth;
            } else {
                bml_btl->btl_weight = 1.0 / mca_bml_base_btl_array_get_size(&ep->btl_rdma);
            }
        }
    }
    
    return OMPI_SUCCESS;
}

int mca_bml_r2_add_btl(mca_btl_base_module_t* btl)
{
    return ORTE_ERR_NOT_IMPLEMENTED;
}


/*
 *  Register callback w/ all active btls
 */
int mca_bml_r2_register( mca_btl_base_tag_t tag, 
                         mca_btl_base_module_recv_cb_fn_t cbfunc, 
                         void* data )
{
    mca_btl_base_active_message_trigger[tag].cbfunc = cbfunc;
    mca_btl_base_active_message_trigger[tag].cbdata = data;
    /* Give an oportunity to the BTLs to do something special
     * for each registration.
     */
    {
        int i, rc;
        mca_btl_base_module_t *btl;

        for(i = 0; i < (int)mca_bml_r2.num_btl_modules; i++) { 
            btl = mca_bml_r2.btl_modules[i];
            if( NULL == btl->btl_register )
                continue;
            rc = btl->btl_register(btl, tag, cbfunc, data);  
            if(OMPI_SUCCESS != rc) {
                return rc;
            }
        }
    }

    return OMPI_SUCCESS; 
}


/*
 *  Register an error handler with/ all active btls
 *   if they support error handlers..
 */

int mca_bml_r2_register_error( 
                        mca_btl_base_module_error_cb_fn_t  cbfunc
                        )
{
    uint32_t  i; 
    int rc;
    mca_btl_base_module_t *btl; 
    uint32_t ver;
    
    for(i = 0; i < mca_bml_r2.num_btl_modules; i++) { 
        btl = mca_bml_r2.btl_modules[i]; 
        /* this wont work for version numbers greater than 256... seems 
           reasonable.. */
        ver = btl->btl_component->btl_version.mca_type_major_version << 16 |
            btl->btl_component->btl_version.mca_type_minor_version << 8 |
            btl->btl_component->btl_version.mca_type_release_version;
        /* is version number greater than or equal to 1.0.1? */
        if(ver >= ((1 << 16) |  (0 << 8) | 1) &&            
           NULL != btl->btl_register_error) { 
            rc = btl->btl_register_error(btl, cbfunc);  
            if(OMPI_SUCCESS != rc) {
                return rc;
            }
        }
    }
    return OMPI_SUCCESS; 
}


int mca_bml_r2_component_fini(void)
{
    /* FIX */
    return OMPI_SUCCESS;
}