text: /* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil -*- */
  /*
   * Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
   *                         University Research and Technology
   *                         Corporation.  All rights reserved.
   * Copyright (c) 2004-2013 The University of Tennessee and The University
   *                         of Tennessee Research Foundation.  All rights
   *                         reserved.
   * Copyright (c) 2004-2008 High Performance Computing Center Stuttgart, 
   *                         University of Stuttgart.  All rights reserved.
   * Copyright (c) 2004-2005 The Regents of the University of California.
   *                         All rights reserved.
   * Copyright (c) 2008      UT-Battelle, LLC. All rights reserved.
   * Copyright (c) 2011      Sandia National Laboratories. All rights reserved.
   * Copyright (c) 2012-2013 NVIDIA Corporation.  All rights reserved.
   * Copyright (c) 2011-2012 Los Alamos National Security, LLC. All rights
   *                         reserved.
   * Copyright (c) 2012      FUJITSU LIMITED.  All rights reserved.
   * Copyright (c) 2014      Research Organization for Information Science
   *                         and Technology (RIST). All rights reserved.
   * $COPYRIGHT$
   * 
   * Additional copyrights may follow
   * 
   * $HEADER$
   */
  
  #include "ompi_config.h"
  
  #include "opal/mca/mpool/mpool.h" 
  #include "opal/util/arch.h"
  #include "ompi/mca/pml/pml.h"
  #include "ompi/mca/bml/bml.h" 
  #include "pml_ob1_comm.h"
  #include "pml_ob1_recvreq.h"
  #include "pml_ob1_recvfrag.h"
  #include "pml_ob1_sendreq.h"
  #include "pml_ob1_rdmafrag.h"
  #include "ompi/mca/bml/base/base.h" 
  #include "ompi/memchecker.h"
  #if OPAL_CUDA_SUPPORT
  #include "opal/datatype/opal_datatype_cuda.h"
  #include "opal/mca/common/cuda/common_cuda.h"
  #endif /* OPAL_CUDA_SUPPORT */
  
  #if OPAL_CUDA_SUPPORT
  int mca_pml_ob1_cuda_need_buffers(mca_pml_ob1_recv_request_t* recvreq,
                                    mca_btl_base_module_t* btl);
  #endif /* OPAL_CUDA_SUPPORT */
  
  void mca_pml_ob1_recv_request_process_pending(void)
  {
      mca_pml_ob1_recv_request_t* recvreq;
      int rc, i, s = (int)opal_list_get_size(&mca_pml_ob1.recv_pending);
  
      for(i = 0; i < s; i++) {
          OPAL_THREAD_LOCK(&mca_pml_ob1.lock);
          recvreq = (mca_pml_ob1_recv_request_t*)
              opal_list_remove_first(&mca_pml_ob1.recv_pending);
          OPAL_THREAD_UNLOCK(&mca_pml_ob1.lock);
          if( OPAL_UNLIKELY(NULL == recvreq) )
              break;
          recvreq->req_pending = false;
          rc = mca_pml_ob1_recv_request_schedule_exclusive(recvreq, NULL);
          if(OMPI_ERR_OUT_OF_RESOURCE == rc)
              break;
      }
  }
  
  static int mca_pml_ob1_recv_request_free(struct ompi_request_t** request)
  {
      mca_pml_ob1_recv_request_t* recvreq = *(mca_pml_ob1_recv_request_t**)request; 
  
      assert( false == recvreq->req_recv.req_base.req_free_called );
  
      OPAL_THREAD_LOCK(&ompi_request_lock);
      recvreq->req_recv.req_base.req_free_called = true;
  
      PERUSE_TRACE_COMM_EVENT( PERUSE_COMM_REQ_NOTIFY,
                               &(recvreq->req_recv.req_base), PERUSE_RECV );
  
      if( true == recvreq->req_recv.req_base.req_pml_complete ) {
          /* make buffer defined when the request is compeleted,
             and before releasing the objects. */
          MEMCHECKER(
              memchecker_call(&opal_memchecker_base_mem_defined,
                              recvreq->req_recv.req_base.req_addr,
                              recvreq->req_recv.req_base.req_count,
                              recvreq->req_recv.req_base.req_datatype);
          );
  
          MCA_PML_OB1_RECV_REQUEST_RETURN( recvreq );
      }
  
      OPAL_THREAD_UNLOCK(&ompi_request_lock);
      *request = MPI_REQUEST_NULL;
      return OMPI_SUCCESS;
  } 
  
  static int mca_pml_ob1_recv_request_cancel(struct ompi_request_t* ompi_request, int complete)
  {
      mca_pml_ob1_recv_request_t* request = (mca_pml_ob1_recv_request_t*)ompi_request;
      mca_pml_ob1_comm_t* comm = request->req_recv.req_base.req_comm->c_pml_comm;
  
      if( true == request->req_match_received ) { /* way to late to cancel this one */
          assert( OMPI_ANY_TAG != ompi_request->req_status.MPI_TAG ); /* not matched isn't it */
          return OMPI_SUCCESS;
      }
  
      /* The rest should be protected behind the match logic lock */
      OPAL_THREAD_LOCK(&comm->matching_lock);
      if( request->req_recv.req_base.req_peer == OMPI_ANY_SOURCE ) {
          opal_list_remove_item( &comm->wild_receives, (opal_list_item_t*)request );
      } else {
          mca_pml_ob1_comm_proc_t* proc = comm->procs + request->req_recv.req_base.req_peer;
          opal_list_remove_item(&proc->specific_receives, (opal_list_item_t*)request);
      }
      PERUSE_TRACE_COMM_EVENT( PERUSE_COMM_REQ_REMOVE_FROM_POSTED_Q,
                               &(request->req_recv.req_base), PERUSE_RECV );
      /**
       * As now the PML is done with this request we have to force the pml_complete
       * to true. Otherwise, the request will never be freed.
       */
      request->req_recv.req_base.req_pml_complete = true;
      OPAL_THREAD_UNLOCK(&comm->matching_lock);
      
      OPAL_THREAD_LOCK(&ompi_request_lock);
      ompi_request->req_status._cancelled = true;
      /* This macro will set the req_complete to true so the MPI Test/Wait* functions
       * on this request will be able to complete. As the status is marked as
       * cancelled the cancel state will be detected.
       */
      MCA_PML_OB1_RECV_REQUEST_MPI_COMPLETE(request);
      OPAL_THREAD_UNLOCK(&ompi_request_lock);
      /*
       * Receive request cancelled, make user buffer accessible.
       */
      MEMCHECKER(
          memchecker_call(&opal_memchecker_base_mem_defined,
                          request->req_recv.req_base.req_addr,
                          request->req_recv.req_base.req_count,
                          request->req_recv.req_base.req_datatype);
      );
      return OMPI_SUCCESS;
  }
  
  static void mca_pml_ob1_recv_request_construct(mca_pml_ob1_recv_request_t* request)
  {
      /* the request type is set by the superclass */
      request->req_recv.req_base.req_ompi.req_free = mca_pml_ob1_recv_request_free;
      request->req_recv.req_base.req_ompi.req_cancel = mca_pml_ob1_recv_request_cancel;
      request->req_rdma_cnt = 0;
      OBJ_CONSTRUCT(&request->lock, opal_mutex_t);
  }
  
  static void mca_pml_ob1_recv_request_destruct(mca_pml_ob1_recv_request_t* request)
  {
      OBJ_DESTRUCT(&request->lock);
  }
  
  OBJ_CLASS_INSTANCE(
      mca_pml_ob1_recv_request_t,
      mca_pml_base_recv_request_t,
      mca_pml_ob1_recv_request_construct,
      mca_pml_ob1_recv_request_destruct);
  
  
  /*
   * Release resources.
   */
  
  static void mca_pml_ob1_recv_ctl_completion( mca_btl_base_module_t* btl,
                                               struct mca_btl_base_endpoint_t* ep,
                                               struct mca_btl_base_descriptor_t* des,
                                               int status )
  {
      mca_bml_base_btl_t* bml_btl = (mca_bml_base_btl_t*)des->des_context;
  
      MCA_PML_OB1_PROGRESS_PENDING(bml_btl);
  }
  
  /*
   * Put operation has completed remotely - update request status
   */
  
  static void mca_pml_ob1_put_completion( mca_btl_base_module_t* btl,
                                          struct mca_btl_base_endpoint_t* ep,
                                          struct mca_btl_base_descriptor_t* des,
                                          int status )
  {
      mca_bml_base_btl_t* bml_btl = (mca_bml_base_btl_t*)des->des_context;
      mca_pml_ob1_recv_request_t* recvreq = (mca_pml_ob1_recv_request_t*)des->des_cbdata;
      size_t bytes_received = 0;
  
      if( OPAL_LIKELY(status == OMPI_SUCCESS) ) {
          bytes_received = mca_pml_ob1_compute_segment_length (btl->btl_seg_size,
                                                               (void *) des->des_local,
                                                               des->des_local_count, 0);
      }
      OPAL_THREAD_ADD_SIZE_T(&recvreq->req_pipeline_depth,-1);
  
      mca_bml_base_free(bml_btl, des);
  
      /* check completion status */
      OPAL_THREAD_ADD_SIZE_T(&recvreq->req_bytes_received, bytes_received);
      if(recv_request_pml_complete_check(recvreq) == false &&
              recvreq->req_rdma_offset < recvreq->req_send_offset) {
          /* schedule additional rdma operations */
          mca_pml_ob1_recv_request_schedule(recvreq, bml_btl);
      }
      MCA_PML_OB1_PROGRESS_PENDING(bml_btl);
  }
  
  /*
   *
   */
  
  int mca_pml_ob1_recv_request_ack_send_btl(
          ompi_proc_t* proc, mca_bml_base_btl_t* bml_btl,
          uint64_t hdr_src_req, void *hdr_dst_req, uint64_t hdr_send_offset,
          bool nordma)
  {
      mca_btl_base_descriptor_t* des;
      mca_pml_ob1_ack_hdr_t* ack;
      int rc;
  
      /* allocate descriptor */
      mca_bml_base_alloc(bml_btl, &des, MCA_BTL_NO_ORDER,
                         sizeof(mca_pml_ob1_ack_hdr_t),
                         MCA_BTL_DES_FLAGS_PRIORITY | MCA_BTL_DES_FLAGS_BTL_OWNERSHIP | 
                         MCA_BTL_DES_SEND_ALWAYS_CALLBACK | MCA_BTL_DES_FLAGS_SIGNAL);
      if( OPAL_UNLIKELY(NULL == des) ) {
          return OMPI_ERR_OUT_OF_RESOURCE; 
      }
  
      /* fill out header */
      ack = (mca_pml_ob1_ack_hdr_t*)des->des_local->seg_addr.pval;
      ack->hdr_common.hdr_type = MCA_PML_OB1_HDR_TYPE_ACK;
      ack->hdr_common.hdr_flags = nordma ? MCA_PML_OB1_HDR_FLAGS_NORDMA : 0;
      ack->hdr_src_req.lval = hdr_src_req;
      ack->hdr_dst_req.pval = hdr_dst_req;
      ack->hdr_send_offset = hdr_send_offset;
  
      ob1_hdr_hton(ack, MCA_PML_OB1_HDR_TYPE_ACK, proc);
  
      /* initialize descriptor */
      des->des_cbfunc = mca_pml_ob1_recv_ctl_completion;
  
      rc = mca_bml_base_send(bml_btl, des, MCA_PML_OB1_HDR_TYPE_ACK);
      if( OPAL_LIKELY( rc >= 0 ) ) {
          return OMPI_SUCCESS;
      }
      mca_bml_base_free(bml_btl, des);
      return OMPI_ERR_OUT_OF_RESOURCE; 
  }
  
  static int mca_pml_ob1_recv_request_ack(
      mca_pml_ob1_recv_request_t* recvreq,
      mca_pml_ob1_rendezvous_hdr_t* hdr, 
      size_t bytes_received)
  {
      ompi_proc_t* proc = (ompi_proc_t*)recvreq->req_recv.req_base.req_proc;
      mca_bml_base_endpoint_t* bml_endpoint = NULL;
  
      bml_endpoint = (mca_bml_base_endpoint_t*) proc->proc_endpoints[OMPI_PROC_ENDPOINT_TAG_BML]; 
  
      /* by default copy everything */
      recvreq->req_send_offset = bytes_received;
      if(hdr->hdr_msg_length > bytes_received) {
          size_t rdma_num = mca_bml_base_btl_array_get_size(&bml_endpoint->btl_rdma);
          /*
           * lookup request buffer to determine if memory is already
           * registered. 
           */
  
          if(opal_convertor_need_buffers(&recvreq->req_recv.req_base.req_convertor) == 0 &&
             hdr->hdr_match.hdr_common.hdr_flags & MCA_PML_OB1_HDR_FLAGS_CONTIG &&
             rdma_num != 0) {
              unsigned char *base;
              opal_convertor_get_current_pointer( &recvreq->req_recv.req_base.req_convertor, (void**)&(base) );
             
              if(hdr->hdr_match.hdr_common.hdr_flags & MCA_PML_OB1_HDR_FLAGS_PIN)
                  recvreq->req_rdma_cnt = mca_pml_ob1_rdma_btls(bml_endpoint,
                          base, recvreq->req_recv.req_bytes_packed,
                          recvreq->req_rdma );
              else
                  recvreq->req_rdma_cnt = 0;
  
              /* memory is already registered on both sides */
              if (recvreq->req_rdma_cnt != 0) {
                  recvreq->req_send_offset = hdr->hdr_msg_length;
                  /* are rdma devices available for long rdma protocol */
              } else if(bml_endpoint->btl_send_limit < hdr->hdr_msg_length) {
                  /* use convertor to figure out the rdma offset for this request */
                  recvreq->req_send_offset = hdr->hdr_msg_length - 
                      bml_endpoint->btl_pipeline_send_length;
  
                  if(recvreq->req_send_offset < bytes_received)
                      recvreq->req_send_offset = bytes_received;
  
                  /* use converter to figure out the rdma offset for this
                   * request */
                  opal_convertor_set_position(&recvreq->req_recv.req_base.req_convertor,
                          &recvreq->req_send_offset);
  
                  recvreq->req_rdma_cnt =
                      mca_pml_ob1_rdma_pipeline_btls(bml_endpoint,
                              recvreq->req_send_offset - bytes_received,
                              recvreq->req_rdma);
              }
          }
          /* nothing to send by copy in/out - no need to ack */
          if(recvreq->req_send_offset == hdr->hdr_msg_length)
              return OMPI_SUCCESS;
      }
      /* let know to shedule function there is no need to put ACK flag */
      recvreq->req_ack_sent = true;
      return mca_pml_ob1_recv_request_ack_send(proc, hdr->hdr_src_req.lval,
                                               recvreq, recvreq->req_send_offset,
                                               recvreq->req_send_offset == bytes_received);
  }
  
  /**
   * Return resources used by the RDMA
   */
  
  static void mca_pml_ob1_rget_completion( mca_btl_base_module_t* btl,
                                           struct mca_btl_base_endpoint_t* ep,
                                           struct mca_btl_base_descriptor_t* des,
                                           int status )
  {
      mca_bml_base_btl_t* bml_btl = (mca_bml_base_btl_t*)des->des_context;
      mca_pml_ob1_rdma_frag_t* frag = (mca_pml_ob1_rdma_frag_t*)des->des_cbdata;
      mca_pml_ob1_recv_request_t* recvreq = (mca_pml_ob1_recv_request_t*)frag->rdma_req;
  
      /* check completion status */
      if( OPAL_UNLIKELY(OMPI_SUCCESS != status) ) {
          /* TSW - FIX */
          OMPI_ERROR_LOG(status);
          ompi_rte_abort(-1, NULL);
      }
  
      /* is receive request complete */
      OPAL_THREAD_ADD_SIZE_T(&recvreq->req_bytes_received, frag->rdma_length);
      if (recvreq->req_recv.req_bytes_packed <= recvreq->req_bytes_received) {
          mca_pml_ob1_send_fin(recvreq->req_recv.req_base.req_proc,
                               bml_btl,
                               frag->rdma_hdr.hdr_rget.hdr_des,
                               des->order, 0);
      }
  
      recv_request_pml_complete_check(recvreq);
  
      MCA_PML_OB1_RDMA_FRAG_RETURN(frag);
  
      MCA_PML_OB1_PROGRESS_PENDING(bml_btl);
  }
  
  
  static int mca_pml_ob1_init_get_fallback (mca_pml_ob1_rdma_frag_t *frag,
                                            mca_btl_base_descriptor_t *dst) {
      mca_pml_ob1_recv_request_t *recvreq = (mca_pml_ob1_recv_request_t *) frag->rdma_req;
      mca_bml_base_btl_t *bml_btl = frag->rdma_bml;
      mca_btl_base_descriptor_t *ctl;
      mca_pml_ob1_rdma_hdr_t *hdr;
      size_t seg_size;
      int rc;
  
      seg_size = bml_btl->btl->btl_seg_size * dst->des_local_count;
  
      /* prepare a descriptor for rdma control message */
      mca_bml_base_alloc (bml_btl, &ctl, MCA_BTL_NO_ORDER, sizeof (mca_pml_ob1_rdma_hdr_t) + seg_size,
                          MCA_BTL_DES_FLAGS_PRIORITY | MCA_BTL_DES_FLAGS_BTL_OWNERSHIP |
                          MCA_BTL_DES_SEND_ALWAYS_CALLBACK | MCA_BTL_DES_FLAGS_SIGNAL);
      if (OPAL_UNLIKELY(NULL == ctl)) {
          return OMPI_ERR_OUT_OF_RESOURCE;
      }
      ctl->des_cbfunc = mca_pml_ob1_recv_ctl_completion;
          
      /* fill in rdma header */
      hdr = (mca_pml_ob1_rdma_hdr_t *) ctl->des_local->seg_addr.pval;
      hdr->hdr_common.hdr_type = MCA_PML_OB1_HDR_TYPE_PUT;
      hdr->hdr_common.hdr_flags =
          (!recvreq->req_ack_sent) ? MCA_PML_OB1_HDR_TYPE_ACK : 0;
  
      hdr->hdr_req = frag->rdma_hdr.hdr_rget.hdr_rndv.hdr_src_req;
      hdr->hdr_rdma_offset = recvreq->req_rdma_offset;
      hdr->hdr_des.pval = dst;
      hdr->hdr_recv_req.pval = recvreq;
  
      hdr->hdr_seg_cnt = dst->des_local_count;
  
      /* copy segments */
      memcpy (hdr + 1, dst->des_local, seg_size);
  
      dst->des_cbfunc = mca_pml_ob1_put_completion;
      dst->des_cbdata = recvreq;
  
      if (!recvreq->req_ack_sent)
          recvreq->req_ack_sent = true;
  
      /* send rdma request to peer */
      rc = mca_bml_base_send (bml_btl, ctl, MCA_PML_OB1_HDR_TYPE_PUT);
      if (OPAL_UNLIKELY(rc < 0)) {
          mca_bml_base_free (bml_btl, ctl);
          return rc;
      }
  
      return OMPI_SUCCESS;
  }
  
  /*
   *
   */
  int mca_pml_ob1_recv_request_get_frag( mca_pml_ob1_rdma_frag_t* frag )
  {
      mca_pml_ob1_recv_request_t* recvreq = (mca_pml_ob1_recv_request_t*)frag->rdma_req;
      mca_bml_base_btl_t* bml_btl = frag->rdma_bml;
      mca_btl_base_descriptor_t* descriptor;
      size_t save_size = frag->rdma_length;
      int rc;
  
      /* prepare descriptor */
      mca_bml_base_prepare_dst( bml_btl, 
                                NULL,
                                &recvreq->req_recv.req_base.req_convertor,
                                MCA_BTL_NO_ORDER,
                                0,
                                &frag->rdma_length,
                                MCA_BTL_DES_FLAGS_BTL_OWNERSHIP | MCA_BTL_DES_SEND_ALWAYS_CALLBACK |
                                MCA_BTL_DES_FLAGS_GET,
                                &descriptor );
      if( OPAL_UNLIKELY(NULL == descriptor) ) {
          if (frag->retries < mca_pml_ob1.rdma_retries_limit) {
              frag->rdma_length = save_size;
              OPAL_THREAD_LOCK(&mca_pml_ob1.lock);
              opal_list_append(&mca_pml_ob1.rdma_pending, (opal_list_item_t*)frag);
              OPAL_THREAD_UNLOCK(&mca_pml_ob1.lock);
              return OMPI_ERR_OUT_OF_RESOURCE;
          } else {
              ompi_proc_t *proc = (ompi_proc_t *) recvreq->req_recv.req_base.req_proc;
  
              /* tell peer to fall back on send */
              recvreq->req_send_offset = 0;
              rc = mca_pml_ob1_recv_request_ack_send(proc, frag->rdma_hdr.hdr_rget.hdr_rndv.hdr_src_req.lval,
                                                     recvreq, recvreq->req_send_offset, true);
              MCA_PML_OB1_RDMA_FRAG_RETURN(frag);
              return rc;
          }
      }
  
      descriptor->des_remote = (mca_btl_base_segment_t *) frag->rdma_segs;
      descriptor->des_remote_count = frag->rdma_hdr.hdr_rdma.hdr_seg_cnt;
      descriptor->des_cbfunc = mca_pml_ob1_rget_completion;
      descriptor->des_cbdata = frag;
  
      PERUSE_TRACE_COMM_OMPI_EVENT(PERUSE_COMM_REQ_XFER_CONTINUE,
                                   &(recvreq->req_recv.req_base),
                                   frag->rdma_length, PERUSE_RECV);
  
      /* queue up get request */
      rc = mca_bml_base_get(bml_btl,descriptor);
      if( OPAL_UNLIKELY(OMPI_SUCCESS != rc) ) {
          if (OPAL_UNLIKELY(OMPI_ERR_NOT_AVAILABLE == rc)) {
              /* get isn't supported for this transfer. tell peer to fallback on put */
              rc = mca_pml_ob1_init_get_fallback (frag, descriptor);
           }
  
          if(OMPI_ERR_OUT_OF_RESOURCE == rc) {
              mca_bml_base_free(bml_btl, descriptor);
              OPAL_THREAD_LOCK(&mca_pml_ob1.lock);
              opal_list_append(&mca_pml_ob1.rdma_pending,
                      (opal_list_item_t*)frag);
              OPAL_THREAD_UNLOCK(&mca_pml_ob1.lock);
              return OMPI_ERR_OUT_OF_RESOURCE;
          } else if (OPAL_UNLIKELY(OMPI_SUCCESS != rc)) {
              OMPI_ERROR_LOG(rc);
              ompi_rte_abort(-1, NULL);
          }
      }
  
      return OMPI_SUCCESS;
  }
  
  
  
  
  /*
   * Update the recv request status to reflect the number of bytes
   * received and actually delivered to the application. 
   */
  
  void mca_pml_ob1_recv_request_progress_frag( mca_pml_ob1_recv_request_t* recvreq,
                                               mca_btl_base_module_t* btl,
                                               mca_btl_base_segment_t* segments,
                                               size_t num_segments )
  {
      size_t bytes_received, data_offset = 0;
      size_t bytes_delivered __opal_attribute_unused__; /* is being set to zero in MCA_PML_OB1_RECV_REQUEST_UNPACK */
      mca_pml_ob1_hdr_t* hdr = (mca_pml_ob1_hdr_t*)segments->seg_addr.pval;
  
      bytes_received = mca_pml_ob1_compute_segment_length_base (segments, num_segments,
                                                                sizeof(mca_pml_ob1_frag_hdr_t));
      data_offset     = hdr->hdr_frag.hdr_frag_offset;
      /*
       *  Make user buffer accessible(defined) before unpacking.
       */
      MEMCHECKER(
                 memchecker_call(&opal_memchecker_base_mem_defined,
                                 recvreq->req_recv.req_base.req_addr,
                                 recvreq->req_recv.req_base.req_count,
                                 recvreq->req_recv.req_base.req_datatype);
                 );
      MCA_PML_OB1_RECV_REQUEST_UNPACK( recvreq,
                                       segments,
                                       num_segments,
                                       sizeof(mca_pml_ob1_frag_hdr_t),
                                       data_offset,
                                       bytes_received,
                                       bytes_delivered );
      /*
       *  Unpacking finished, make the user buffer unaccessable again.
       */
      MEMCHECKER(
                 memchecker_call(&opal_memchecker_base_mem_noaccess,
                                 recvreq->req_recv.req_base.req_addr,
                                 recvreq->req_recv.req_base.req_count,
                                 recvreq->req_recv.req_base.req_datatype);
                 );
      
      OPAL_THREAD_ADD_SIZE_T(&recvreq->req_bytes_received, bytes_received);
      /* check completion status */
      if(recv_request_pml_complete_check(recvreq) == false &&
              recvreq->req_rdma_offset < recvreq->req_send_offset) {
          /* schedule additional rdma operations */
          mca_pml_ob1_recv_request_schedule(recvreq, NULL);
      }
  }
  
  #if OPAL_CUDA_SUPPORT /* CUDA_ASYNC_RECV */
  /**
   * This function is basically the first half of the code in the
   * mca_pml_ob1_recv_request_progress_frag function.  This fires off
   * the asynchronous copy and returns.  Unused fields in the descriptor
   * are used to pass extra information for when the asynchronous copy
   * completes.  No memchecker support in this function as copies are 
   * happening asynchronously.
   */
  void mca_pml_ob1_recv_request_frag_copy_start( mca_pml_ob1_recv_request_t* recvreq,
                                                 mca_btl_base_module_t* btl,
                                                 mca_btl_base_segment_t* segments,
                                                 size_t num_segments,
                                                 mca_btl_base_descriptor_t* des)
  {
      int result;
      size_t bytes_received = 0, data_offset = 0;
      size_t bytes_delivered __opal_attribute_unused__; /* is being set to zero in MCA_PML_OB1_RECV_REQUEST_UNPACK */
      mca_pml_ob1_hdr_t* hdr = (mca_pml_ob1_hdr_t*)segments->seg_addr.pval;
  
      OPAL_OUTPUT((-1, "start_frag_copy frag=%p", (void *)des));
  
      bytes_received = mca_pml_ob1_compute_segment_length_base (segments, num_segments,
                                                                sizeof(mca_pml_ob1_frag_hdr_t));
      data_offset     = hdr->hdr_frag.hdr_frag_offset;
  
      MCA_PML_OB1_RECV_REQUEST_UNPACK( recvreq,
                                       segments,
                                       num_segments,
                                       sizeof(mca_pml_ob1_frag_hdr_t),
                                       data_offset,
                                       bytes_received,
                                       bytes_delivered );
      /* Store the receive request in unused context pointer. */
      des->des_context = (void *)recvreq;
      /* Store the amount of bytes in unused remote count value */
      des->des_remote_count = bytes_delivered;
      /* Then record an event that will get triggered by a PML progress call which
       * checks the stream events.  If we get an error, abort.  Should get message
       * from CUDA code about what went wrong. */
      result = mca_common_cuda_record_htod_event("pml", des);
      if (OMPI_SUCCESS != result) {
          opal_output(0, "%s:%d FATAL", __FILE__, __LINE__);
          ompi_rte_abort(-1, NULL);
      }
  }
  
  /**
   * This function is basically the second half of the code in the
   * mca_pml_ob1_recv_request_progress_frag function.  The number of
   * bytes delivered is updated.  Then a call is made into the BTL so it
   * can free the fragment that held that data.  This is currently
   * called directly by the common CUDA code. No memchecker support
   * in this function as copies are happening asynchronously.
   */
  void mca_pml_ob1_recv_request_frag_copy_finished( mca_btl_base_module_t* btl,
                                                    struct mca_btl_base_endpoint_t* ep,
                                                    struct mca_btl_base_descriptor_t* des,
                                                    int status )
  {
      mca_pml_ob1_recv_request_t* recvreq = (mca_pml_ob1_recv_request_t*)des->des_context;
      size_t bytes_received = des->des_remote_count;
  
      OPAL_OUTPUT((-1, "frag_copy_finished (delivered=%d), frag=%p", (int)bytes_received, (void *)des));
      /* Call into the BTL so it can free the descriptor.  At this point, it is 
       * known that the data has been copied out of the descriptor. */
      des->des_cbfunc(NULL, (struct mca_btl_base_endpoint_t *)des->des_cbdata, des, 0);
  
      OPAL_THREAD_ADD_SIZE_T(&recvreq->req_bytes_received, bytes_received);
  
      /* check completion status */
      if(recv_request_pml_complete_check(recvreq) == false &&
              recvreq->req_rdma_offset < recvreq->req_send_offset) {
          /* schedule additional rdma operations */
          mca_pml_ob1_recv_request_schedule(recvreq, NULL);
      }
  }
  #endif /* OPAL_CUDA_SUPPORT */
  
  /*
   * Update the recv request status to reflect the number of bytes
   * received and actually delivered to the application. 
   */
  
  void mca_pml_ob1_recv_request_progress_rget( mca_pml_ob1_recv_request_t* recvreq,
                                               mca_btl_base_module_t* btl,
                                               mca_btl_base_segment_t* segments,
                                               size_t num_segments )
  {
      mca_pml_ob1_rget_hdr_t* hdr = (mca_pml_ob1_rget_hdr_t*)segments->seg_addr.pval;
      mca_bml_base_endpoint_t* bml_endpoint = NULL;
      size_t bytes_remaining, prev_sent, offset;
      mca_btl_base_segment_t *r_segments;
      mca_pml_ob1_rdma_frag_t *frag;
      mca_bml_base_btl_t *rdma_bml;
      int rc;
  
      prev_sent = offset = 0;
      bytes_remaining = hdr->hdr_rndv.hdr_msg_length;
      recvreq->req_recv.req_bytes_packed = hdr->hdr_rndv.hdr_msg_length;
  
      MCA_PML_OB1_RECV_REQUEST_MATCHED(recvreq, &hdr->hdr_rndv.hdr_match);
      
      /* if receive buffer is not contiguous we can't just RDMA read into it, so
       * fall back to copy in/out protocol. It is a pity because buffer on the
       * sender side is already registered. We need to be smarter here, perhaps
       * do couple of RDMA reads */
      if (opal_convertor_need_buffers(&recvreq->req_recv.req_base.req_convertor) == true) {
  #if OPAL_CUDA_SUPPORT
          if (mca_pml_ob1_cuda_need_buffers(recvreq, btl))
  #endif /* OPAL_CUDA_SUPPORT */
          {
              mca_pml_ob1_recv_request_ack(recvreq, &hdr->hdr_rndv, 0);
              return;
          }
      }
      
      /* lookup bml datastructures */
      bml_endpoint = (mca_bml_base_endpoint_t*)recvreq->req_recv.req_base.req_proc->proc_endpoints[OMPI_PROC_ENDPOINT_TAG_BML];
      rdma_bml = mca_bml_base_btl_array_find(&bml_endpoint->btl_rdma, btl);
  
  #if OPAL_CUDA_SUPPORT
      if (OPAL_UNLIKELY(NULL == rdma_bml)) {
          if (recvreq->req_recv.req_base.req_convertor.flags & CONVERTOR_CUDA) {
              mca_bml_base_btl_t *bml_btl;
              bml_btl = mca_bml_base_btl_array_find(&bml_endpoint->btl_send, btl);
              /* Check to see if this is a CUDA get */
              if (bml_btl->btl_flags & MCA_BTL_FLAGS_CUDA_GET) {
                  rdma_bml = bml_btl;
              }
          } else {
              /* Just default back to send and receive.  Must be mix of GPU and HOST memory. */
              mca_pml_ob1_recv_request_ack(recvreq, &hdr->hdr_rndv, 0);
              return;
          }
      }
  #endif /* OPAL_CUDA_SUPPORT */
  
      if (OPAL_UNLIKELY(NULL == rdma_bml)) {
          opal_output(0, "[%s:%d] invalid bml for rdma get", __FILE__, __LINE__);
          ompi_rte_abort(-1, NULL);
      }
  
      bytes_remaining = mca_pml_ob1_compute_segment_length_remote (btl->btl_seg_size, (void *)(hdr + 1),
                                                                   hdr->hdr_seg_cnt, recvreq->req_recv.req_base.req_proc);
  
      /* The while loop adds a fragmentation mechanism. The variable bytes_remaining holds the num
       * of bytes left to be send. In each iteration we send the max possible bytes supported
       * by the HCA. The field  frag->rdma_length holds the actual num of  bytes that were
       * sent in each iteration. We subtract this number from bytes_remaining and continue to
       * the next iteration with the updated size.
       * Also - In each iteration we update the location in the buffer to be used for writing
       * the message ,and the location to read from. This is done using the offset variable that
       * accumulates the number of bytes that were sent so far. */
      while (bytes_remaining > 0) {
          /* allocate/initialize a fragment */
          MCA_PML_OB1_RDMA_FRAG_ALLOC(frag);
          if (OPAL_UNLIKELY(NULL == frag)) {
              /* GLB - FIX */
               OMPI_ERROR_LOG(OMPI_ERR_OUT_OF_RESOURCE);
               ompi_rte_abort(-1, NULL);
          }
  
          assert (btl->btl_seg_size * hdr->hdr_seg_cnt <= sizeof (frag->rdma_segs));
  
          memcpy (frag->rdma_segs, hdr + 1, btl->btl_seg_size * hdr->hdr_seg_cnt);
  
          /* update the read location -- NTH: note this will only work if there is exactly one
             segment. TODO -- make this work with multiple segments */
          r_segments = (mca_btl_base_segment_t *) frag->rdma_segs;
          r_segments->seg_addr.lval += offset;
  
          /* updating the write location */
          OPAL_THREAD_LOCK(&recvreq->lock);
          opal_convertor_set_position( &recvreq->req_recv.req_base.req_convertor, &offset);
          OPAL_THREAD_UNLOCK(&recvreq->lock);
  
          frag->rdma_bml = rdma_bml;
  
          frag->rdma_hdr.hdr_rget = *hdr;
          frag->retries     = 0;
          frag->rdma_req    = recvreq;
          frag->rdma_ep     = bml_endpoint;
          frag->rdma_state  = MCA_PML_OB1_RDMA_GET;
          frag->reg         = NULL;
          frag->rdma_length = bytes_remaining;
  
          /* NTH: TODO -- handle error conditions gracefully */
          rc = mca_pml_ob1_recv_request_get_frag(frag);
          if (OMPI_SUCCESS != rc) {
              break;
          }
  
          prev_sent = frag->rdma_length;
          bytes_remaining -= prev_sent;
          offset += prev_sent;
      }
  }
  
  /*
   * Update the recv request status to reflect the number of bytes
   * received and actually delivered to the application. 
   */
  
  void mca_pml_ob1_recv_request_progress_rndv( mca_pml_ob1_recv_request_t* recvreq,
                                               mca_btl_base_module_t* btl,
                                               mca_btl_base_segment_t* segments,
                                               size_t num_segments )
  {
      size_t bytes_received = 0;
      size_t bytes_delivered __opal_attribute_unused__; /* is being set to zero in MCA_PML_OB1_RECV_REQUEST_UNPACK */
      size_t data_offset = 0;
      mca_pml_ob1_hdr_t* hdr = (mca_pml_ob1_hdr_t*)segments->seg_addr.pval;
  
      bytes_received = mca_pml_ob1_compute_segment_length_base (segments, num_segments,
                                                                sizeof(mca_pml_ob1_rendezvous_hdr_t));
  
      recvreq->req_recv.req_bytes_packed = hdr->hdr_rndv.hdr_msg_length;
      recvreq->remote_req_send = hdr->hdr_rndv.hdr_src_req;
      recvreq->req_rdma_offset = bytes_received;
      MCA_PML_OB1_RECV_REQUEST_MATCHED(recvreq, &hdr->hdr_match);
      mca_pml_ob1_recv_request_ack(recvreq, &hdr->hdr_rndv, bytes_received);
      /**
       * The PUT protocol do not attach any data to the original request.
       * Therefore, we might want to avoid unpacking if there is nothing to
       * unpack.
       */
      if( 0 < bytes_received ) {
          MEMCHECKER(
                     memchecker_call(&opal_memchecker_base_mem_defined,
                                     recvreq->req_recv.req_base.req_addr,
                                     recvreq->req_recv.req_base.req_count,
                                     recvreq->req_recv.req_base.req_datatype);
                     );
          MCA_PML_OB1_RECV_REQUEST_UNPACK( recvreq,
                                           segments,
                                           num_segments,
                                           sizeof(mca_pml_ob1_rendezvous_hdr_t),
                                           data_offset,
                                           bytes_received,
                                           bytes_delivered );
          MEMCHECKER(
                     memchecker_call(&opal_memchecker_base_mem_noaccess,
                                     recvreq->req_recv.req_base.req_addr,
                                     recvreq->req_recv.req_base.req_count,
                                     recvreq->req_recv.req_base.req_datatype);
                     );
      }
      OPAL_THREAD_ADD_SIZE_T(&recvreq->req_bytes_received, bytes_received);
      /* check completion status */
      if(recv_request_pml_complete_check(recvreq) == false &&
         recvreq->req_rdma_offset < recvreq->req_send_offset) {
          /* schedule additional rdma operations */
          mca_pml_ob1_recv_request_schedule(recvreq, NULL);
      }
  
  #if OPAL_CUDA_SUPPORT /* CUDA_ASYNC_RECV */
      /* If BTL supports it and this is a CUDA buffer being received into,
       * have all subsequent FRAGS copied in asynchronously. */
      if ((recvreq->req_recv.req_base.req_convertor.flags & CONVERTOR_CUDA) &&
          (btl->btl_flags & MCA_BTL_FLAGS_CUDA_COPY_ASYNC_RECV)) {
          void *strm = mca_common_cuda_get_htod_stream();
          opal_cuda_set_copy_function_async(&recvreq->req_recv.req_base.req_convertor, strm);
      }
  #endif
      
  }
  
  /*
   * Update the recv request status to reflect the number of bytes
   * received and actually delivered to the application. 
   */
  void mca_pml_ob1_recv_request_progress_match( mca_pml_ob1_recv_request_t* recvreq,
                                                mca_btl_base_module_t* btl,
                                                mca_btl_base_segment_t* segments,
                                                size_t num_segments )
  {
      size_t bytes_received, data_offset = 0;
      size_t bytes_delivered __opal_attribute_unused__; /* is being set to zero in MCA_PML_OB1_RECV_REQUEST_UNPACK */
      mca_pml_ob1_hdr_t* hdr = (mca_pml_ob1_hdr_t*)segments->seg_addr.pval;
  
      bytes_received = mca_pml_ob1_compute_segment_length_base (segments, num_segments,
                                                                OMPI_PML_OB1_MATCH_HDR_LEN);
  
      recvreq->req_recv.req_bytes_packed = bytes_received;
      
      MCA_PML_OB1_RECV_REQUEST_MATCHED(recvreq, &hdr->hdr_match);
      /*
       *  Make user buffer accessable(defined) before unpacking.
       */
      MEMCHECKER(
                 memchecker_call(&opal_memchecker_base_mem_defined,
                                 recvreq->req_recv.req_base.req_addr,
                                 recvreq->req_recv.req_base.req_count,
                                 recvreq->req_recv.req_base.req_datatype);
                 );
      MCA_PML_OB1_RECV_REQUEST_UNPACK( recvreq,
                                       segments,
                                       num_segments,
                                       OMPI_PML_OB1_MATCH_HDR_LEN,
                                       data_offset,
                                       bytes_received,
                                       bytes_delivered);
      /*
       *  Unpacking finished, make the user buffer unaccessable again.
       */
      MEMCHECKER(
                 memchecker_call(&opal_memchecker_base_mem_noaccess,
                                 recvreq->req_recv.req_base.req_addr,
                                 recvreq->req_recv.req_base.req_count,
                                 recvreq->req_recv.req_base.req_datatype);
                 );
      
      /*
       * No need for atomic here, as we know there is only one fragment
       * for this request.
       */
      recvreq->req_bytes_received += bytes_received;
      recv_request_pml_complete(recvreq);
  }
  
  
  /**
   * Handle completion of a probe request
   */
  
  void mca_pml_ob1_recv_request_matched_probe( mca_pml_ob1_recv_request_t* recvreq,
                                               mca_btl_base_module_t* btl,
                                               mca_btl_base_segment_t* segments,
                                               size_t num_segments )
  {
      size_t bytes_packed = 0;
      mca_pml_ob1_hdr_t* hdr = (mca_pml_ob1_hdr_t*)segments->seg_addr.pval;
  
      switch(hdr->hdr_common.hdr_type) {
          case MCA_PML_OB1_HDR_TYPE_MATCH:
              bytes_packed = mca_pml_ob1_compute_segment_length_base (segments, num_segments,
                                                                      OMPI_PML_OB1_MATCH_HDR_LEN);
              break;
          case MCA_PML_OB1_HDR_TYPE_RNDV:
          case MCA_PML_OB1_HDR_TYPE_RGET:
  
              bytes_packed = hdr->hdr_rndv.hdr_msg_length;
              break;
      }
  
      /* set completion status */
      recvreq->req_recv.req_base.req_ompi.req_status.MPI_TAG = hdr->hdr_match.hdr_tag;
      recvreq->req_recv.req_base.req_ompi.req_status.MPI_SOURCE = hdr->hdr_match.hdr_src;
      recvreq->req_bytes_received = bytes_packed;
      recvreq->req_bytes_expected = bytes_packed;
  
      recv_request_pml_complete(recvreq);
  }
  
  
  /*
   * Schedule RDMA protocol.
   *
  */
  
  int mca_pml_ob1_recv_request_schedule_once( mca_pml_ob1_recv_request_t* recvreq,
                                              mca_bml_base_btl_t *start_bml_btl )
  {
      mca_bml_base_btl_t* bml_btl; 
      int num_tries = recvreq->req_rdma_cnt, num_fail = 0;
      size_t i, prev_bytes_remaining = 0;
      size_t bytes_remaining = recvreq->req_send_offset -
          recvreq->req_rdma_offset;
  
      /* if starting bml_btl is provided schedule next fragment on it first */
      if(start_bml_btl != NULL) {
          for(i = 0; i < recvreq->req_rdma_cnt; i++) {
              if(recvreq->req_rdma[i].bml_btl != start_bml_btl)
                  continue;
              /* something left to be send? */
              if( OPAL_LIKELY(recvreq->req_rdma[i].length) )
                  recvreq->req_rdma_idx = i;
              break;
          }
      }
  
      while(bytes_remaining > 0 &&
             recvreq->req_pipeline_depth < mca_pml_ob1.recv_pipeline_depth) {
          size_t size, seg_size;
          mca_pml_ob1_rdma_hdr_t* hdr;
          mca_btl_base_descriptor_t* dst;
          mca_btl_base_descriptor_t* ctl;
          mca_mpool_base_registration_t * reg = NULL;
          mca_btl_base_module_t* btl;
          int rc, rdma_idx;
  
          if(prev_bytes_remaining == bytes_remaining) {
              if(++num_fail == num_tries) {
                  OPAL_THREAD_LOCK(&mca_pml_ob1.lock);
                  if(false == recvreq->req_pending) {
                      opal_list_append(&mca_pml_ob1.recv_pending,
                              (opal_list_item_t*)recvreq);
                      recvreq->req_pending = true;
                  }
                  OPAL_THREAD_UNLOCK(&mca_pml_ob1.lock);
                  return OMPI_ERR_OUT_OF_RESOURCE;
              }
          } else {
              num_fail = 0;
              prev_bytes_remaining = bytes_remaining;
          }
  
          do {
              rdma_idx = recvreq->req_rdma_idx;
              bml_btl = recvreq->req_rdma[rdma_idx].bml_btl;
              reg = recvreq->req_rdma[rdma_idx].btl_reg;
              size = recvreq->req_rdma[rdma_idx].length;
              if(++recvreq->req_rdma_idx >= recvreq->req_rdma_cnt)
                  recvreq->req_rdma_idx = 0;
          } while(!size);
          btl = bml_btl->btl;
  
          /* makes sure that we don't exceed BTL max rdma size
           * if memory is not pinned already */
          if( (NULL == reg) && (btl->btl_rdma_pipeline_frag_size != 0) &&
                               (size > btl->btl_rdma_pipeline_frag_size)) {
              size = btl->btl_rdma_pipeline_frag_size;
          }
  
          /* take lock to protect converter against concurrent access
           * from unpack */
          OPAL_THREAD_LOCK(&recvreq->lock);
          opal_convertor_set_position( &recvreq->req_recv.req_base.req_convertor,
                                       &recvreq->req_rdma_offset );
  
          /* prepare a descriptor for RDMA */
          mca_bml_base_prepare_dst(bml_btl, reg, 
                                   &recvreq->req_recv.req_base.req_convertor,
                                   MCA_BTL_NO_ORDER, 0, &size, MCA_BTL_DES_FLAGS_BTL_OWNERSHIP |
                                   MCA_BTL_DES_FLAGS_PUT, &dst);
          OPAL_THREAD_UNLOCK(&recvreq->lock);
  
          if(OPAL_UNLIKELY(dst == NULL)) {
              continue;
          }
  
          dst->des_cbfunc = mca_pml_ob1_put_completion;
          dst->des_cbdata = recvreq;
  
          seg_size = btl->btl_seg_size * dst->des_local_count;
  
          /* prepare a descriptor for rdma control message */
          mca_bml_base_alloc(bml_btl, &ctl, MCA_BTL_NO_ORDER, sizeof(mca_pml_ob1_rdma_hdr_t) + seg_size,
                             MCA_BTL_DES_FLAGS_PRIORITY | MCA_BTL_DES_FLAGS_BTL_OWNERSHIP | 
                             MCA_BTL_DES_SEND_ALWAYS_CALLBACK | MCA_BTL_DES_FLAGS_SIGNAL);
  
          if( OPAL_UNLIKELY(NULL == ctl) ) {
              mca_bml_base_free(bml_btl,dst);
              continue;
          }
          ctl->des_cbfunc = mca_pml_ob1_recv_ctl_completion;
          
          /* fill in rdma header */
          hdr = (mca_pml_ob1_rdma_hdr_t*)ctl->des_local->seg_addr.pval;
          hdr->hdr_common.hdr_type = MCA_PML_OB1_HDR_TYPE_PUT;
          hdr->hdr_common.hdr_flags =
              (!recvreq->req_ack_sent) ? MCA_PML_OB1_HDR_TYPE_ACK : 0;
          hdr->hdr_req = recvreq->remote_req_send;
          hdr->hdr_des.pval = dst;
          hdr->hdr_recv_req.pval = recvreq;
          hdr->hdr_rdma_offset = recvreq->req_rdma_offset;
          hdr->hdr_seg_cnt = dst->des_local_count;
  
          /* copy segments */
          memmove (hdr + 1, dst->des_local, seg_size);
  
          if(!recvreq->req_ack_sent)
              recvreq->req_ack_sent = true;
          ob1_hdr_hton(hdr, MCA_PML_OB1_HDR_TYPE_PUT, recvreq->req_recv.req_base.req_proc);
  
          PERUSE_TRACE_COMM_OMPI_EVENT( PERUSE_COMM_REQ_XFER_CONTINUE,
                                        &(recvreq->req_recv.req_base), size,
                                        PERUSE_RECV);
  
          /* send rdma request to peer */
          rc = mca_bml_base_send(bml_btl, ctl, MCA_PML_OB1_HDR_TYPE_PUT);
          if( OPAL_LIKELY( rc >= 0 ) ) {
              /* update request state */
              recvreq->req_rdma_offset += size;
              OPAL_THREAD_ADD_SIZE_T(&recvreq->req_pipeline_depth, 1);
              recvreq->req_rdma[rdma_idx].length -= size;
              bytes_remaining -= size;
          } else {
              mca_bml_base_free(bml_btl,ctl);
              mca_bml_base_free(bml_btl,dst);
          }
      }
  
      return OMPI_SUCCESS;
  }
  
  #define IS_PROB_REQ(R) \
      ((MCA_PML_REQUEST_IPROBE == (R)->req_recv.req_base.req_type) || \
       (MCA_PML_REQUEST_PROBE == (R)->req_recv.req_base.req_type) || \
       (MCA_PML_REQUEST_IMPROBE == (R)->req_recv.req_base.req_type) || \
       (MCA_PML_REQUEST_MPROBE == (R)->req_recv.req_base.req_type))
  #define IS_MPROB_REQ(R) \
      ((MCA_PML_REQUEST_IMPROBE == (R)->req_recv.req_base.req_type) || \
       (MCA_PML_REQUEST_MPROBE == (R)->req_recv.req_base.req_type))
  
  static inline void append_recv_req_to_queue(opal_list_t *queue,
          mca_pml_ob1_recv_request_t *req)
  {
      if(OPAL_UNLIKELY(req->req_recv.req_base.req_type == MCA_PML_REQUEST_IPROBE ||
                       req->req_recv.req_base.req_type == MCA_PML_REQUEST_IMPROBE))
          return;
  
      opal_list_append(queue, (opal_list_item_t*)req);
  
      /**
       * We don't want to generate this kind of event for MPI_Probe. Hopefully,
       * the compiler will optimize out the empty if loop in the case where PERUSE
       * support is not required by the user.
       */
      if(req->req_recv.req_base.req_type != MCA_PML_REQUEST_PROBE ||
         req->req_recv.req_base.req_type != MCA_PML_REQUEST_MPROBE) {
          PERUSE_TRACE_COMM_EVENT(PERUSE_COMM_REQ_INSERT_IN_POSTED_Q,
                                  &(req->req_recv.req_base), PERUSE_RECV);
      }
  }
  
  /*
   *  this routine tries to match a posted receive.  If a match is found,
   *  it places the request in the appropriate matched receive list. This
   *  function has to be called with the communicator matching lock held.
  */
  static mca_pml_ob1_recv_frag_t*
  recv_req_match_specific_proc( const mca_pml_ob1_recv_request_t *req,
                                mca_pml_ob1_comm_proc_t *proc )
  {
      opal_list_t* unexpected_frags = &proc->unexpected_frags;
      opal_list_item_t *i;
      mca_pml_ob1_recv_frag_t* frag;
      int tag = req->req_recv.req_base.req_tag;
  
      if(opal_list_get_size(unexpected_frags) == 0)
          return NULL;
  
      if( OMPI_ANY_TAG == tag ) {
          for (i =  opal_list_get_first(unexpected_frags);
               i != opal_list_get_end(unexpected_frags);
               i =  opal_list_get_next(i)) {
              frag = (mca_pml_ob1_recv_frag_t*)i;
              
              if( frag->hdr.hdr_match.hdr_tag >= 0 )
                  return frag;
          }
      } else {
          for (i =  opal_list_get_first(unexpected_frags);
               i != opal_list_get_end(unexpected_frags);
               i =  opal_list_get_next(i)) {
              frag = (mca_pml_ob1_recv_frag_t*)i;
              
              if( frag->hdr.hdr_match.hdr_tag == tag )
                  return frag;
          }
      }
      return NULL;
  }
  
  /*
   * this routine is used to try and match a wild posted receive - where
   * wild is determined by the value assigned to the source process
  */
  static mca_pml_ob1_recv_frag_t*
  recv_req_match_wild( mca_pml_ob1_recv_request_t* req,
                       mca_pml_ob1_comm_proc_t **p)
  {
      mca_pml_ob1_comm_t* comm = req->req_recv.req_base.req_comm->c_pml_comm;
      mca_pml_ob1_comm_proc_t* proc = comm->procs;
      size_t i;
  
      /*
       * Loop over all the outstanding messages to find one that matches.
       * There is an outer loop over lists of messages from each
       * process, then an inner loop over the messages from the
       * process.
       *
       * In order to avoid starvation do this in a round-robin fashion.
       */
      for (i = comm->last_probed + 1; i < comm->num_procs; i++) {
          mca_pml_ob1_recv_frag_t* frag;
  
          /* loop over messages from the current proc */
          if((frag = recv_req_match_specific_proc(req, &proc[i]))) {
              *p = &proc[i];
              comm->last_probed = i;
              req->req_recv.req_base.req_proc = proc[i].ompi_proc;
              prepare_recv_req_converter(req);
              return frag; /* match found */
          }
      }
      for (i = 0; i <= comm->last_probed; i++) {
          mca_pml_ob1_recv_frag_t* frag;
  
          /* loop over messages from the current proc */
          if((frag = recv_req_match_specific_proc(req, &proc[i]))) {
              *p = &proc[i];
              comm->last_probed = i;
              req->req_recv.req_base.req_proc = proc[i].ompi_proc;
              prepare_recv_req_converter(req);
              return frag; /* match found */
          }
      }
  
      *p = NULL;
      return NULL;
  }
  
  
  void mca_pml_ob1_recv_req_start(mca_pml_ob1_recv_request_t *req)
  {
      mca_pml_ob1_comm_t* comm = req->req_recv.req_base.req_comm->c_pml_comm;
      mca_pml_ob1_comm_proc_t* proc;
      mca_pml_ob1_recv_frag_t* frag;
      opal_list_t *queue;
      mca_pml_ob1_hdr_t* hdr;
  
      /* init/re-init the request */
      req->req_lock = 0;
      req->req_pipeline_depth = 0;
      req->req_bytes_received = 0;
      req->req_bytes_expected = 0;
      /* What about req_rdma_cnt ? */
      req->req_rdma_idx = 0;
      req->req_pending = false;
      req->req_ack_sent = false;
  
      MCA_PML_BASE_RECV_START(&req->req_recv.req_base);
  
      OPAL_THREAD_LOCK(&comm->matching_lock);
      /**
       * The laps of time between the ACTIVATE event and the SEARCH_UNEX one include
       * the cost of the request lock.
       */
      PERUSE_TRACE_COMM_EVENT(PERUSE_COMM_SEARCH_UNEX_Q_BEGIN,
                              &(req->req_recv.req_base), PERUSE_RECV);
  
      /* assign sequence number */
      req->req_recv.req_base.req_sequence = comm->recv_sequence++;
  
      /* attempt to match posted recv */
      if(req->req_recv.req_base.req_peer == OMPI_ANY_SOURCE) {
          frag = recv_req_match_wild(req, &proc);
          queue = &comm->wild_receives;
  #if !OPAL_ENABLE_HETEROGENEOUS_SUPPORT
          /* As we are in a homogeneous environment we know that all remote
           * architectures are exactly the same as the local one. Therefore,
           * we can safely construct the convertor based on the proc
           * information of rank 0.
           */
          if( NULL == frag ) {
              req->req_recv.req_base.req_proc = ompi_proc_local_proc;
              prepare_recv_req_converter(req);
          }
  #endif  /* !OPAL_ENABLE_HETEROGENEOUS_SUPPORT */
      } else {
          proc = &comm->procs[req->req_recv.req_base.req_peer];
          req->req_recv.req_base.req_proc = proc->ompi_proc;
          frag = recv_req_match_specific_proc(req, proc);
          queue = &proc->specific_receives;
          /* wild cardrecv will be prepared on match */ 
          prepare_recv_req_converter(req);
      }
  
      if(OPAL_UNLIKELY(NULL == frag)) {
          PERUSE_TRACE_COMM_EVENT(PERUSE_COMM_SEARCH_UNEX_Q_END,
                                  &(req->req_recv.req_base), PERUSE_RECV);
          /* We didn't find any matches.  Record this irecv so we can match
             it when the message comes in. */
          append_recv_req_to_queue(queue, req);
          req->req_match_received = false;
          OPAL_THREAD_UNLOCK(&comm->matching_lock);
      } else {
          if(OPAL_LIKELY(!IS_PROB_REQ(req))) {
              PERUSE_TRACE_COMM_EVENT(PERUSE_COMM_REQ_MATCH_UNEX,
                                      &(req->req_recv.req_base), PERUSE_RECV);
  
              hdr = (mca_pml_ob1_hdr_t*)frag->segments->seg_addr.pval;
              PERUSE_TRACE_MSG_EVENT(PERUSE_COMM_MSG_REMOVE_FROM_UNEX_Q,
                                     req->req_recv.req_base.req_comm,
                                     hdr->hdr_match.hdr_src,
                                     hdr->hdr_match.hdr_tag,
                                     PERUSE_RECV);
  
              PERUSE_TRACE_COMM_EVENT(PERUSE_COMM_SEARCH_UNEX_Q_END,
                                      &(req->req_recv.req_base), PERUSE_RECV);
  
              opal_list_remove_item(&proc->unexpected_frags,
                                    (opal_list_item_t*)frag);
              OPAL_THREAD_UNLOCK(&comm->matching_lock);
              
              switch(hdr->hdr_common.hdr_type) {
              case MCA_PML_OB1_HDR_TYPE_MATCH:
                  mca_pml_ob1_recv_request_progress_match(req, frag->btl, frag->segments,
                                                          frag->num_segments);
                  break;
              case MCA_PML_OB1_HDR_TYPE_RNDV:
                  mca_pml_ob1_recv_request_progress_rndv(req, frag->btl, frag->segments,
                                                         frag->num_segments);
                  break;
              case MCA_PML_OB1_HDR_TYPE_RGET:
                  mca_pml_ob1_recv_request_progress_rget(req, frag->btl, frag->segments,
                                                         frag->num_segments);
                  break;
              default:
                  assert(0);
              }
              
              MCA_PML_OB1_RECV_FRAG_RETURN(frag);
  
          } else if (OPAL_UNLIKELY(IS_MPROB_REQ(req))) {
              /* Remove the fragment from the match list, as it's now
                 matched.  Stash it somewhere in the request (which,
                 yes, is a complete hack), where it will be plucked out
                 during the end of mprobe.  The request will then be
                 "recreated" as a receive request, and the frag will be
                 restarted with this request during mrecv */
              opal_list_remove_item(&proc->unexpected_frags,
                                    (opal_list_item_t*)frag);
              OPAL_THREAD_UNLOCK(&comm->matching_lock);
  
              req->req_recv.req_base.req_addr = frag;
              mca_pml_ob1_recv_request_matched_probe(req, frag->btl,
                                                     frag->segments, frag->num_segments);
  
          } else {
              OPAL_THREAD_UNLOCK(&comm->matching_lock);
              mca_pml_ob1_recv_request_matched_probe(req, frag->btl,
                                                     frag->segments, frag->num_segments);
          }
      }
  }
  