File: pml_ob1_recvfrag.c

package info (click to toggle)
openmpi 1.2.7~rc2-2
  • links: PTS, VCS
  • area: main
  • in suites: lenny
  • size: 41,300 kB
  • ctags: 24,303
  • sloc: ansic: 224,835; sh: 22,627; makefile: 7,037; cpp: 6,353; asm: 3,547; lex: 528; objc: 383; perl: 348; csh: 89; f90: 49; fortran: 47; tcl: 12
file content (767 lines) | stat: -rw-r--r-- 34,741 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
/*
 * Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
 *                         University Research and Technology
 *                         Corporation.  All rights reserved.
 * Copyright (c) 2004-2006 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) 2004-2005 The Regents of the University of California.
 *                         All rights reserved.
 * $COPYRIGHT$
 * 
 * Additional copyrights may follow
 * 
 * $HEADER$
 */

/**
 * @file
 */

#include "ompi_config.h"

#include "opal/class/opal_list.h"
#include "opal/threads/mutex.h"
#include "ompi/constants.h"
#include "ompi/communicator/communicator.h"
#include "ompi/mca/pml/pml.h"
#include "pml_ob1.h"
#include "pml_ob1_comm.h"
#include "pml_ob1_recvfrag.h"
#include "pml_ob1_recvreq.h"
#include "pml_ob1_sendreq.h"
#include "pml_ob1_hdr.h"
#include "ompi/datatype/dt_arch.h"
#include "ompi/peruse/peruse-internal.h"

OBJ_CLASS_INSTANCE( mca_pml_ob1_buffer_t,
                    ompi_free_list_item_t,
                    NULL,
                    NULL );

OBJ_CLASS_INSTANCE( mca_pml_ob1_recv_frag_t,
                    opal_list_item_t,
                    NULL,
                    NULL );

/**
 * Static functions.
 */

/**
 * Match incoming recv_frags against posted receives.  
 * Supports out of order delivery.
 * 
 * @param frag_header (IN)          Header of received recv_frag.
 * @param frag_desc (IN)            Received recv_frag descriptor.
 * @param match_made (OUT)          Flag indicating wether a match was made.
 * @param additional_matches (OUT)  List of additional matches 
 * @return                          OMPI_SUCCESS or error status on failure.
 */
static int mca_pml_ob1_recv_frag_match( mca_btl_base_module_t *btl, 
                                        mca_pml_ob1_match_hdr_t *hdr,
                                        mca_btl_base_segment_t* segments,
                                        size_t num_segments );

/**
 *  Callback from BTL on receive.
 */
                                                                                                                      
void mca_pml_ob1_recv_frag_callback( mca_btl_base_module_t* btl, 
                                     mca_btl_base_tag_t tag,
                                     mca_btl_base_descriptor_t* des,
                                     void* cbdata )
{
    mca_btl_base_segment_t* segments = des->des_dst;
    mca_pml_ob1_hdr_t* hdr = (mca_pml_ob1_hdr_t*)segments->seg_addr.pval;

    if(segments->seg_len < sizeof(mca_pml_ob1_common_hdr_t)) {
        return;
    }

    /* hdr_type and hdr_flags are uint8_t, so no endian problems */
    switch(hdr->hdr_common.hdr_type) {
    case MCA_PML_OB1_HDR_TYPE_MATCH:
        {
#if !defined(WORDS_BIGENDIAN) && OMPI_ENABLE_HETEROGENEOUS_SUPPORT
            if (hdr->hdr_common.hdr_flags & MCA_PML_OB1_HDR_FLAGS_NBO) {
                MCA_PML_OB1_MATCH_HDR_NTOH(hdr->hdr_match);
            }
#endif
            mca_pml_ob1_recv_frag_match(btl, &hdr->hdr_match, segments,des->des_dst_cnt);
            break;
        }
    case MCA_PML_OB1_HDR_TYPE_RNDV:
        {
#if !defined(WORDS_BIGENDIAN) && OMPI_ENABLE_HETEROGENEOUS_SUPPORT
            if (hdr->hdr_common.hdr_flags & MCA_PML_OB1_HDR_FLAGS_NBO) {
                MCA_PML_OB1_RNDV_HDR_NTOH(hdr->hdr_rndv);
            }
#endif
            mca_pml_ob1_recv_frag_match(btl, &hdr->hdr_match, segments,des->des_dst_cnt);
            break;
        }
    case MCA_PML_OB1_HDR_TYPE_RGET:
        {
#if !defined(WORDS_BIGENDIAN) && OMPI_ENABLE_HETEROGENEOUS_SUPPORT
            /* RDMA is currently disabled by bml if arch doesn't
               match, so this shouldn't be needed.  here to make sure
               we remember if we ever change the bml. */
            assert(0 == (hdr->hdr_common.hdr_flags & MCA_PML_OB1_HDR_FLAGS_NBO));
#endif
            mca_pml_ob1_recv_frag_match(btl, &hdr->hdr_match, segments,des->des_dst_cnt);
            break;
        }
    case MCA_PML_OB1_HDR_TYPE_ACK:
        {
            mca_pml_ob1_send_request_t* sendreq;
#if !defined(WORDS_BIGENDIAN) && OMPI_ENABLE_HETEROGENEOUS_SUPPORT
            if (hdr->hdr_common.hdr_flags & MCA_PML_OB1_HDR_FLAGS_NBO) {
                MCA_PML_OB1_ACK_HDR_NTOH(hdr->hdr_ack);
            }
#endif
            sendreq = (mca_pml_ob1_send_request_t*)hdr->hdr_ack.hdr_src_req.pval;
            sendreq->req_recv = hdr->hdr_ack.hdr_dst_req;
            sendreq->req_rdma_offset = (size_t)hdr->hdr_ack.hdr_rdma_offset;
            if(OPAL_THREAD_ADD32(&sendreq->req_state, 1) == 2 &&
                    sendreq->req_bytes_delivered >=
                    sendreq->req_send.req_bytes_packed) {
                MCA_PML_OB1_SEND_REQUEST_PML_COMPLETE(sendreq);
            } else {
                mca_pml_ob1_send_request_schedule(sendreq);
            }
                
            break;
        }
    case MCA_PML_OB1_HDR_TYPE_FRAG:
        {
            mca_pml_ob1_recv_request_t* recvreq;
#if !defined(WORDS_BIGENDIAN) && OMPI_ENABLE_HETEROGENEOUS_SUPPORT
            if (hdr->hdr_common.hdr_flags & MCA_PML_OB1_HDR_FLAGS_NBO) {
                MCA_PML_OB1_FRAG_HDR_NTOH(hdr->hdr_frag);
            }
#endif
            recvreq = (mca_pml_ob1_recv_request_t*)hdr->hdr_frag.hdr_dst_req.pval;
            mca_pml_ob1_recv_request_progress(recvreq,btl,segments,des->des_dst_cnt);
            break;
        }
    case MCA_PML_OB1_HDR_TYPE_PUT:
        {
            mca_pml_ob1_send_request_t* sendreq;
#if !defined(WORDS_BIGENDIAN) && OMPI_ENABLE_HETEROGENEOUS_SUPPORT
            /* RDMA is currently disabled by bml if arch doesn't
               match, so this shouldn't be needed.  here to make sure
               we remember if we ever change the bml. */
            assert(0 == (hdr->hdr_common.hdr_flags & MCA_PML_OB1_HDR_FLAGS_NBO));
#endif
            sendreq = (mca_pml_ob1_send_request_t*)hdr->hdr_rdma.hdr_req.pval;
            mca_pml_ob1_send_request_put(sendreq,btl,&hdr->hdr_rdma);
            break;
        }
    case MCA_PML_OB1_HDR_TYPE_FIN:
        {
            mca_btl_base_descriptor_t* rdma;
#if !defined(WORDS_BIGENDIAN) && OMPI_ENABLE_HETEROGENEOUS_SUPPORT
            if (hdr->hdr_common.hdr_flags & MCA_PML_OB1_HDR_FLAGS_NBO) {
                MCA_PML_OB1_FIN_HDR_NTOH(hdr->hdr_fin);
            }
#endif
            rdma = (mca_btl_base_descriptor_t*)hdr->hdr_fin.hdr_des.pval;
            rdma->des_cbfunc(btl, NULL, rdma, OMPI_SUCCESS);
            break;
        }
    default:
        break;
    }
}

/**
 * Try and match the incoming message fragment to a generic
 * list of receives
 *
 * @param hdr Matching data from received fragment (IN)
 *
 * @param generic_receives Pointer to the receive list used for
 * matching purposes. (IN)
 *
 * @return Matched receive
 *
 * This routine assumes that the appropriate matching locks are
 * set by the upper level routine.
 */
#define MCA_PML_OB1_MATCH_GENERIC_RECEIVES(hdr,generic_receives,proc,return_match) \
    do {                                                                           \
        /* local variables */                                                      \
        mca_pml_ob1_recv_request_t *generic_recv = (mca_pml_ob1_recv_request_t *)  \
                     opal_list_get_first(generic_receives);                        \
        mca_pml_ob1_recv_request_t *last_recv = (mca_pml_ob1_recv_request_t *)     \
            opal_list_get_end(generic_receives);                                   \
        register int recv_tag, frag_tag = hdr->hdr_tag;                            \
                                                                                   \
        /* Loop over the receives. If the received tag is less than zero  */       \
        /* enter in a special mode, where we match only our internal tags */       \
        /* (such as those used by the collectives.*/                               \
        if( 0 <= frag_tag ) {                                                      \
            for( ; generic_recv != last_recv;                                      \
                 generic_recv = (mca_pml_ob1_recv_request_t *)                     \
                     ((opal_list_item_t *)generic_recv)->opal_list_next) {         \
                /* Check for a match */                                            \
                recv_tag = generic_recv->req_recv.req_base.req_tag;                \
                if ( (frag_tag == recv_tag) || (recv_tag == OMPI_ANY_TAG) ) {      \
                    break;                                                         \
                }                                                                  \
            }                                                                      \
        } else {                                                                   \
            for( ; generic_recv != last_recv;                                      \
                 generic_recv = (mca_pml_ob1_recv_request_t *)                     \
                     ((opal_list_item_t *)generic_recv)->opal_list_next) {         \
                /* Check for a match */                                            \
                recv_tag = generic_recv->req_recv.req_base.req_tag;                \
                if(frag_tag == recv_tag) {                        \
                    break;                                                         \
                }                                                                  \
            }                                                                      \
        }                                                                          \
        if( generic_recv != (mca_pml_ob1_recv_request_t *)                         \
            opal_list_get_end(generic_receives) ) {                                \
                                                                                   \
            /* Match made */                                                       \
            return_match = generic_recv;                                           \
                                                                                   \
            /* remove descriptor from posted specific ireceive list */             \
            opal_list_remove_item(generic_receives,                                \
                                  (opal_list_item_t *)generic_recv);               \
                                                                                   \
        }                                                                          \
    } while(0)

/**
 * Try and match the incoming message fragment to the list of
 * "wild" receives
 *
 * @param hdr Matching data from recived fragment (IN)
 *
 * @param pml_comm Pointer to the communicator structure used for
 * matching purposes. (IN)
 *
 * @return Matched receive
 *
 * This routine assumes that the appropriate matching locks are
 * set by the upper level routine.
 */

#define MCA_PML_OB1_CHECK_WILD_RECEIVES_FOR_MATCH(hdr,comm,proc,return_match) \
do { \
    /* local parameters */ \
    opal_list_t* wild_receives = &comm->wild_receives; \
    MCA_PML_OB1_MATCH_GENERIC_RECEIVES(hdr,wild_receives,proc,return_match); \
} while(0)


/**
 * Try and match the incoming message fragment to the list of
 * "specific" receives
 *
 * @param hdr Matching data from recived fragment (IN)
 *
 * @param comm Pointer to the communicator structure used for
 * matching purposes. (IN)
 *
 * @return Matched receive
 *
 * This routine assumes that the appropriate matching locks are
 * set by the upper level routine.
 */
#define MCA_PML_OB1_CHECK_SPECIFIC_RECEIVES_FOR_MATCH(hdr,comm,proc,return_match) \
do { \
    /* local variables */ \
    opal_list_t* specific_receives = &proc->specific_receives; \
    MCA_PML_OB1_MATCH_GENERIC_RECEIVES(hdr,specific_receives,proc,return_match); \
} while(0)

/**
 * Try and match the incoming message fragment to the list of
 * "wild" receives and "specific" receives.  Used when both types
 * of receives have been posted,  i.e. when we need to coordinate
 * between multiple lists to make sure ordered delivery occurs.
 *
 * @param hdr Matching data from recived fragment (IN)
 *
 * @param comm Pointer to the communicator structure used for
 * matching purposes. (IN)
 *
 * @return Matched receive
 *
 * This routine assumes that the appropriate matching locks are
 * set by the upper level routine.
 */

#define MCA_PML_OB1_CHECK_SPECIFIC_AND_WILD_RECEIVES_FOR_MATCH( hdr,comm,proc,return_match) \
    do {                                                                \
        /* local variables */                                           \
        mca_pml_ob1_recv_request_t *specific_recv, *wild_recv;          \
        mca_pml_sequence_t wild_recv_seq, specific_recv_seq;            \
        int frag_tag, wild_recv_tag, specific_recv_tag;                 \
                                                                        \
        /* initialization */                                            \
        frag_tag=hdr->hdr_tag;                                          \
                                                                        \
        /*                                                              \
         * We know that when this is called, both specific and wild irecvs \
         *  have been posted.                                           \
         */                                                             \
        specific_recv = (mca_pml_ob1_recv_request_t *)                  \
            opal_list_get_first(&(proc)->specific_receives);            \
        wild_recv = (mca_pml_ob1_recv_request_t *)                      \
            opal_list_get_first(&comm->wild_receives);                  \
                                                                        \
        specific_recv_seq = specific_recv->req_recv.req_base.req_sequence; \
        wild_recv_seq = wild_recv->req_recv.req_base.req_sequence;      \
                                                                        \
        while (true) {                                                  \
            if (wild_recv_seq < specific_recv_seq) {                    \
                /* wild recv is earlier than the specific one. */       \
                /* try and match */                                     \
                wild_recv_tag = wild_recv->req_recv.req_base.req_tag;   \
                if ( (frag_tag == wild_recv_tag) ||                     \
                     ( (wild_recv_tag == OMPI_ANY_TAG) && (0 <= frag_tag) ) ) { \
                    /* Match made */                                    \
                    return_match=wild_recv;                             \
                                                                        \
                    /* remove this recv from the wild receive queue */  \
                    opal_list_remove_item(&comm->wild_receives,         \
                                          (opal_list_item_t *)wild_recv); \
                                                                        \
                    PERUSE_TRACE_COMM_EVENT (PERUSE_COMM_REQ_REMOVE_FROM_POSTED_Q, \
                                             &(wild_recv->req_recv.req_base), \
                                             PERUSE_RECV);              \
                                                                        \
                    break;                                              \
                }                                                       \
                                                                        \
                /* No match, go to the next */                          \
                wild_recv=(mca_pml_ob1_recv_request_t *)                \
                    ((opal_list_item_t *)wild_recv)->opal_list_next;    \
                                                                        \
                /*                                                      \
                 * If that was the last wild one, just look at the      \
                 * rest of the specific ones.                           \
                 */                                                     \
                if (wild_recv == (mca_pml_ob1_recv_request_t *)         \
                    opal_list_get_end(&comm->wild_receives) )           \
                    {                                                   \
                        MCA_PML_OB1_CHECK_SPECIFIC_RECEIVES_FOR_MATCH(hdr, comm, proc, return_match); \
                        break;                                          \
                    }                                                   \
                                                                        \
                /*                                                      \
                 * Get the sequence number for this recv, and go        \
                 * back to the top of the loop.                         \
                 */                                                     \
                wild_recv_seq = wild_recv->req_recv.req_base.req_sequence; \
                                                                        \
            } else {                                                    \
                /* specific recv is earlier than the wild one. */       \
                specific_recv_tag=specific_recv->req_recv.req_base.req_tag; \
                if ( (frag_tag == specific_recv_tag) ||                 \
                     ( (specific_recv_tag == OMPI_ANY_TAG) && (0<=frag_tag)) ) \
                    {                                                   \
                        /* Match made */                                \
                        return_match = specific_recv;                   \
                        /* remove descriptor from specific receive list */ \
                        opal_list_remove_item(&(proc)->specific_receives, \
                                              (opal_list_item_t *)specific_recv); \
                                                                        \
                        PERUSE_TRACE_COMM_EVENT (PERUSE_COMM_REQ_REMOVE_FROM_POSTED_Q, \
                                                 &(specific_recv->req_recv.req_base), \
                                                 PERUSE_RECV);          \
                                                                        \
                        break;                                          \
                    }                                                   \
                                                                        \
                /* No match, go on to the next specific irecv. */       \
                specific_recv = (mca_pml_ob1_recv_request_t *)          \
                    ((opal_list_item_t *)specific_recv)->opal_list_next; \
                                                                        \
                /*                                                      \
                 * If that was the last specific irecv, process the     \
                 * rest of the wild ones.                               \
                 */                                                     \
                if (specific_recv == (mca_pml_ob1_recv_request_t *)     \
                    opal_list_get_end(&(proc)->specific_receives))      \
                    {                                                   \
                        MCA_PML_OB1_CHECK_WILD_RECEIVES_FOR_MATCH(hdr, comm, proc, return_match); \
                        break;                                          \
                    }                                                   \
                /*                                                      \
                 * Get the sequence number for this recv, and go        \
                 * back to the top of the loop.                         \
                 */                                                     \
                specific_recv_seq = specific_recv->req_recv.req_base.req_sequence; \
            }                                                           \
        }                                                               \
    } while(0)


/*
 * Specialized matching routines for internal use only.
 */

static bool mca_pml_ob1_check_cantmatch_for_match( opal_list_t *additional_matches,
                                                   mca_pml_ob1_comm_t* comm,
                                                   mca_pml_ob1_comm_proc_t *proc );

/**
 * RCS/CTS receive side matching
 *
 * @param hdr list of parameters needed for matching
 *                    This list is also embeded in frag,
 *                    but this allows to save a memory copy when
 *                    a match is made in this routine. (IN)
 * @param frag   pointer to receive fragment which we want
 *                    to match (IN/OUT).  If a match is not made,
 *                    hdr is copied to frag.
 * @param match_made  parameter indicating if we matched frag/
 *                    hdr (OUT)
 * @param additional_matches  if a match is made with frag, we
 *                    may be able to match fragments that previously
 *                    have arrived out-of-order.  If this is the
 *                    case, the associated fragment descriptors are
 *                    put on this list for further processing. (OUT)
 *
 * @return OMPI error code
 *
 * This routine is used to try and match a newly arrived message fragment
 *   to pre-posted receives.  The following assumptions are made
 *   - fragments are received out of order
 *   - for long messages, e.g. more than one fragment, a RTS/CTS algorithm
 *       is used.
 *   - 2nd and greater fragments include a receive descriptor pointer
 *   - fragments may be dropped
 *   - fragments may be corrupt
 *   - this routine may be called simultaneously by more than one thread
 */
static int mca_pml_ob1_recv_frag_match( mca_btl_base_module_t *btl, 
                                        mca_pml_ob1_match_hdr_t *hdr,
                                        mca_btl_base_segment_t* segments,
                                        size_t num_segments )
{
    /* local variables */
    uint16_t next_msg_seq_expected, frag_msg_seq;
    ompi_communicator_t *comm_ptr;
    mca_pml_ob1_recv_request_t *match = NULL;
    mca_pml_ob1_comm_t *comm;
    mca_pml_ob1_comm_proc_t *proc;
    bool additional_match=false;
    opal_list_t additional_matches;
    int rc;

    /* communicator pointer */
    comm_ptr=ompi_comm_lookup(hdr->hdr_ctx);
    comm=(mca_pml_ob1_comm_t *)comm_ptr->c_pml_comm;

    /* source sequence number */
    frag_msg_seq = hdr->hdr_seq;
    proc = comm->procs + hdr->hdr_src;

    /**
     * We generate the MSG_ARRIVED event as soon as the PML is aware of a matching
     * fragment arrival. Independing if it is received on the correct order or not.
     * This will allow the tools to figure out if the messages are not received in the
     * correct order (if multiple network interfaces).
     */
    PERUSE_TRACE_MSG_EVENT( PERUSE_COMM_MSG_ARRIVED, comm_ptr,
                            hdr->hdr_src, hdr->hdr_tag, PERUSE_RECV);

    /* get next expected message sequence number - if threaded
     * run, lock to make sure that if another thread is processing 
     * a frag from the same message a match is made only once.
     * Also, this prevents other posted receives (for a pair of
     * end points) from being processed, and potentially "loosing"
     * the fragment.
     */
    OPAL_THREAD_LOCK(&comm->matching_lock);

    /* get sequence number of next message that can be processed */
    next_msg_seq_expected = (uint16_t)proc->expected_sequence;
    if(frag_msg_seq == next_msg_seq_expected) {

        /*
         * This is the sequence number we were expecting,
         * so we can try matching it to already posted
         * receives.
         */

        /* We're now expecting the next sequence number. */
        (proc->expected_sequence)++;

        /**
         * We generate the SEARCH_POSTED_QUEUE only when the message is received
         * in the correct sequence. Otherwise, we delay the event generation until
         * we reach the correct sequence number.
         */
        PERUSE_TRACE_MSG_EVENT( PERUSE_COMM_SEARCH_POSTED_Q_BEGIN, comm_ptr,
                                hdr->hdr_src, hdr->hdr_tag, PERUSE_RECV);

rematch:

        /*
         * figure out what sort of matching logic to use, if need to
         *   look only at "specific" receives, or "wild" receives,
         *   or if we need to traverse both sets at the same time.
         */
        if (opal_list_get_size(&proc->specific_receives) == 0 ){
            /*
             * There are only wild irecvs, so specialize the algorithm.
             */
            MCA_PML_OB1_CHECK_WILD_RECEIVES_FOR_MATCH(hdr, comm, proc, match);
    
        } else if (opal_list_get_size(&comm->wild_receives) == 0 ) {
            /*
             * There are only specific irecvs, so specialize the algorithm.
             */
            MCA_PML_OB1_CHECK_SPECIFIC_RECEIVES_FOR_MATCH(hdr, comm, proc, match);
        } else {
            /*
             * There are some of each.
             */
            MCA_PML_OB1_CHECK_SPECIFIC_AND_WILD_RECEIVES_FOR_MATCH(hdr, comm, proc, match);
        }

        /* if match found, process data */
        if(match) {
            match->req_recv.req_base.req_proc = proc->ompi_proc;

            /*
             * update delivered sequence number information, if needed.
             */
            if( (match->req_recv.req_base.req_type == MCA_PML_REQUEST_PROBE) ) {

                /* complete the probe */
                mca_pml_ob1_recv_request_matched_probe(match,btl,segments,num_segments);

                /* attempt to match actual request */
                match = NULL;
                goto rematch;
            }
        } else {

            /* if no match found, place on unexpected queue */
            mca_pml_ob1_recv_frag_t* frag;
            MCA_PML_OB1_RECV_FRAG_ALLOC(frag, rc);
            if(OMPI_SUCCESS != rc) {
                OPAL_THREAD_UNLOCK(&comm->matching_lock);
                /**
                 * As we return from the match function, we should generate the expected event.
                 */
                PERUSE_TRACE_MSG_EVENT( PERUSE_COMM_SEARCH_POSTED_Q_END, comm_ptr,
                                        hdr->hdr_src, hdr->hdr_tag, PERUSE_RECV);

                return rc;
            }
            MCA_PML_OB1_RECV_FRAG_INIT(frag,hdr,segments,num_segments,btl);
            opal_list_append( &proc->unexpected_frags, (opal_list_item_t *)frag );
        }

        /**
         * The match is over. We generate the SEARCH_POSTED_Q_END here, before going
         * into the mca_pml_ob1_check_cantmatch_for_match so we can make a difference
         * for the searching time for all messages.
         */
        PERUSE_TRACE_MSG_EVENT( PERUSE_COMM_SEARCH_POSTED_Q_END, comm_ptr,
                                hdr->hdr_src, hdr->hdr_tag, PERUSE_RECV);

        /* 
         * Now that new message has arrived, check to see if
         *   any fragments on the c_c_frags_cant_match list
         *   may now be used to form new matchs
         */
        if (0 < opal_list_get_size(&proc->frags_cant_match)) {
            additional_match = mca_pml_ob1_check_cantmatch_for_match(&additional_matches,comm,proc);
        }

    } else {

        /*
         * This message comes after the next expected, so it
         * is ahead of sequence.  Save it for later.
         */
        mca_pml_ob1_recv_frag_t* frag;
        MCA_PML_OB1_RECV_FRAG_ALLOC(frag, rc);
        if(OMPI_SUCCESS != rc) {
            OPAL_THREAD_UNLOCK(&comm->matching_lock);
            return rc;
        }
        MCA_PML_OB1_RECV_FRAG_INIT(frag,hdr,segments,num_segments,btl);
        opal_list_append(&proc->frags_cant_match, (opal_list_item_t *)frag);

    }
    /* release matching lock before processing fragment */
    OPAL_THREAD_UNLOCK(&comm->matching_lock);

    if(match != NULL) {
        mca_pml_ob1_recv_request_progress(match,btl,segments,num_segments);
    } else {
        PERUSE_TRACE_MSG_EVENT( PERUSE_COMM_MSG_INSERT_IN_UNEX_Q, comm_ptr,
                                hdr->hdr_src, hdr->hdr_tag, PERUSE_RECV);
    } 
    if(additional_match) {
        opal_list_item_t* item;
        while(NULL != (item = opal_list_remove_first(&additional_matches))) {
            mca_pml_ob1_recv_frag_t* frag = (mca_pml_ob1_recv_frag_t*)item;
            mca_pml_ob1_recv_request_progress( frag->request, frag->btl, frag->segments,
                                               frag->num_segments );
            MCA_PML_OB1_RECV_FRAG_RETURN(frag);
        }
    }
    return OMPI_SUCCESS;
}


/**
 * Scan the list of frags that came in ahead of time to see if any
 * can be processed at this time.  If they can, try and match the
 * frags.
 *
 * @param additional_matches List to hold new matches with fragments
 * from the c_frags_cant_match list. (IN/OUT)
 *
 * @param pml_comm Pointer to the communicator structure used for
 * matching purposes. (IN)
 *
 * This routine assumes that the appropriate matching locks are
 * set by the upper level routine.
 */

static bool mca_pml_ob1_check_cantmatch_for_match( opal_list_t *additional_matches,
                                                   mca_pml_ob1_comm_t* comm,
                                                   mca_pml_ob1_comm_proc_t *proc )
{
    /* local parameters */
    int match_found;
    uint16_t next_msg_seq_expected, frag_seq;
    mca_pml_ob1_recv_frag_t *frag;
    bool match_made = false;

    /*
     * Loop over all the out of sequence messages.  No ordering is assumed
     * in the c_frags_cant_match list.
     */

    match_found = 1;
    while ((0 < opal_list_get_size(&proc->frags_cant_match)) && match_found) {

        /* initialize match flag for this search */
        match_found = 0;

        /* get sequence number of next message that can be processed */
        next_msg_seq_expected = proc->expected_sequence;

        /* search the list for a fragment from the send with sequence
         * number next_msg_seq_expected
         */
        for(frag = (mca_pml_ob1_recv_frag_t *) 
            opal_list_get_first(&proc->frags_cant_match);
            frag != (mca_pml_ob1_recv_frag_t *)
            opal_list_get_end(&proc->frags_cant_match);
            frag = (mca_pml_ob1_recv_frag_t *) 
            opal_list_get_next(frag))
        {
            /*
             * If the message has the next expected seq from that proc...
             */
            frag_seq=frag->hdr.hdr_match.hdr_seq;
            if (frag_seq == next_msg_seq_expected) {
                mca_pml_ob1_match_hdr_t* hdr = &frag->hdr.hdr_match;
                mca_pml_ob1_recv_request_t *match = NULL;

                /* We're now expecting the next sequence number. */
                (proc->expected_sequence)++;

                /* signal that match was made */
                match_found = 1;

                /*
                 * remove frag from list
                 */
                opal_list_remove_item(&proc->frags_cant_match,
                        (opal_list_item_t *)frag);

rematch:
                /*
                 * figure out what sort of matching logic to use, if need to
                 *   look only at "specific" receives, or "wild" receives,
                 *   or if we need to traverse both sets at the same time.
                 */
                proc = comm->procs + hdr->hdr_src;
                if (opal_list_get_size(&proc->specific_receives) == 0 ) {
                    /*
                     * There are only wild irecvs, so specialize the algorithm.
                     */
                    MCA_PML_OB1_CHECK_WILD_RECEIVES_FOR_MATCH(hdr, comm, proc, match);
                } else if (opal_list_get_size(&comm->wild_receives) == 0 ) {
                    /*
                     * There are only specific irecvs, so specialize the algorithm.
                     */
                    MCA_PML_OB1_CHECK_SPECIFIC_RECEIVES_FOR_MATCH(hdr, comm, proc, match);
                } else {
                    /*
                     * There are some of each.
                     */
                    MCA_PML_OB1_CHECK_SPECIFIC_AND_WILD_RECEIVES_FOR_MATCH(hdr, comm, proc, match);

                }

                /* if match found, process data */
                if(match) {
                    match->req_recv.req_base.req_proc = proc->ompi_proc;

                    /*
                     * If this was a probe need to queue fragment on unexpected list
                     */
                    if( (match->req_recv.req_base.req_type == MCA_PML_REQUEST_PROBE) ) {

                        /* complete the probe */
                        mca_pml_ob1_recv_request_matched_probe(match,frag->btl,frag->segments,frag->num_segments);

                        /* retry the match */
                        match = NULL;
                        goto rematch;

                    } else {

                        /* associate the receive descriptor with the fragment
                         * descriptor */
                        frag->request=match;

                        /* add this fragment descriptor to the list of
                         * descriptors to be processed later
                         */
                        if(match_made == false) {
                            match_made = true;
                            OBJ_CONSTRUCT(additional_matches, opal_list_t);
                        }
                        opal_list_append(additional_matches, (opal_list_item_t *)frag);
                    }

                } else {
    
                    /* if no match found, place on unexpected queue */
                    opal_list_append( &proc->unexpected_frags, (opal_list_item_t *)frag);
                }

                /* c_frags_cant_match is not an ordered list, so exit loop
                 * and re-start search for next sequence number */
                break;

            } /* end if (frag_seq == next_msg_seq_expected) */
            
        } /* end for (frag) loop */
        
    } /* end while loop */

    return match_made;
}