OpenMPI  0.1.1
btl_udapl.h
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1 /* -*- Mode: C; c-basic-offset:4 ; -*- */
2 /*
3  * Copyright (c) 2004-2007 The Trustees of Indiana University and Indiana
4  * University Research and Technology
5  * Corporation. All rights reserved.
6  * Copyright (c) 2004-2009 The University of Tennessee and The University
7  * of Tennessee Research Foundation. All rights
8  * reserved.
9  * Copyright (c) 2004-2005 High Performance Computing Center Stuttgart,
10  * University of Stuttgart. All rights reserved.
11  * Copyright (c) 2004-2005 The Regents of the University of California.
12  * All rights reserved.
13  * Copyright (c) 2007-2009 Sun Microsystems, Inc. All rights reserved.
14  * Copyright (c) 2007 Cisco Systems, Inc. All rights reserved.
15  *
16  * $COPYRIGHT$
17  *
18  * Additional copyrights may follow
19  *
20  * $HEADER$
21  */
22 /**
23  * @file
24  */
25 #ifndef MCA_BTL_UDAPL_H
26 #define MCA_BTL_UDAPL_H
27 
28 #include "ompi_config.h"
29 #include <sys/types.h>
30 #include <string.h>
31 #include <dat/udat.h>
32 
33 /* Open MPI includes */
35 #include "opal/mca/event/event.h"
36 #include "ompi/class/ompi_free_list.h"
37 #include "ompi/mca/btl/btl.h"
38 #include "ompi/mca/btl/base/base.h"
39 #include "ompi/mca/btl/base/btl_base_error.h"
40 #include "orte/util/show_help.h"
41 #include "ompi/mca/mpool/mpool.h"
42 #include "ompi/mca/btl/btl.h"
43 #include "btl_udapl_endpoint.h"
44 
45 BEGIN_C_DECLS
46 
47 
48 /**
49  * uDAPL BTL component.
50  */
51 
53  mca_btl_base_component_2_0_0_t super; /**< base BTL component */
54 
55  int32_t udapl_verbosity; /**< report out level, see
56  "Report Out from uDAPL BTL" below for details. */
57  size_t udapl_num_btls; /**< number of hcas available to the uDAPL component */
58  size_t udapl_max_btls; /**< maximum number of supported hcas */
59  struct mca_btl_udapl_module_t **udapl_btls; /**< array of available BTL modules */
60  int32_t udapl_num_recvs; /**< number of recv buffers to keep posted */
61  int32_t udapl_num_sends; /**< number of sends to post on endpoint */
62  int32_t udapl_sr_win; /**< number of fragments recieved before
63  returning credits to sender */
64  uint32_t udapl_timeout; /**< connection timeout, in microseconds */
65  size_t udapl_eager_frag_size;
66  size_t udapl_max_frag_size;
67  size_t udapl_eager_rdma_frag_size; /* size of the rdma fragement including data
68  * payload space
69  */
70 
71  int udapl_free_list_num; /**< initial size of free lists */
72  int udapl_free_list_max; /**< maximum size of free lists */
73  int udapl_free_list_inc; /**< number of elements to alloc when growing */
74  int32_t udapl_use_eager_rdma; /**< turn rdma for small msgs on/off */
75  int32_t udapl_eager_rdma_num; /**< number of rdma buffers allocated
76  for short messages */
77  int32_t udapl_max_eager_rdma_peers; /**< maximum number of peers allowed to
78  use RDMA for short messages (cap)
79  */
80  int32_t udapl_eager_rdma_win; /**< number of eager RDMA fragments
81  recieved before returning credits to
82  sender */
83  int32_t udapl_conn_priv_data; /**< use connect priv data for proc data */
84  int32_t udapl_async_events; /**< dequeue asynchronous events */
85  int32_t udapl_buffer_alignment; /**< preferred communication buffer alignment, in bytes */
86  opal_list_t udapl_procs; /**< list of udapl proc structures */
87  opal_mutex_t udapl_lock; /**< lock for accessing module state */
88  char* udapl_mpool_name; /**< name of memory pool */
89  int32_t udapl_compare_subnet;/**< whether to compare with netmask or not */
90  char *if_include;
91  char **if_include_list;
92  char *if_exclude;
93  char **if_exclude_list;
94  char **if_list; /* used for checking entries not found */
95  int32_t ro_aware_system; /* default 0; 1 if relaxed ordered platform */
96 };
98 
99 OMPI_MODULE_DECLSPEC extern mca_btl_udapl_component_t mca_btl_udapl_component;
100 
101 
102 
103 /**
104  * BTL Module Interface
105  */
107  mca_btl_base_module_t super; /**< base BTL interface */
108  mca_btl_udapl_addr_t udapl_addr;
109 
110  /* uDAPL interface and other handles */
111  DAT_IA_HANDLE udapl_ia;
112  DAT_PZ_HANDLE udapl_pz;
113  DAT_PSP_HANDLE udapl_psp;
114  DAT_IA_ATTR udapl_ia_attr;
115 
116  /* event dispatchers - async, data transfer, connection negotiation */
117  DAT_EVD_HANDLE udapl_evd_async;
118  DAT_EVD_HANDLE udapl_evd_dto;
119  DAT_EVD_HANDLE udapl_evd_conn;
120  DAT_EP_PARAM udapl_ep_param;
121 
122  /* free list of fragment descriptors */
123  ompi_free_list_t udapl_frag_eager;
124  ompi_free_list_t udapl_frag_eager_recv;
125  ompi_free_list_t udapl_frag_max;
126  ompi_free_list_t udapl_frag_max_recv;
127  ompi_free_list_t udapl_frag_user;
128  ompi_free_list_t udapl_frag_control;
129 
130  opal_mutex_t udapl_lock; /* lock for accessing module state */
131  opal_mutex_t udapl_eager_rdma_lock; /* eager rdma lock */
132  int32_t udapl_eager_rdma_endpoint_count; /* count of the number of
133  * endpoints in
134  * udapl_eager_rdma_endpoints
135  */
136  opal_pointer_array_t *udapl_eager_rdma_endpoints; /* array of endpoints
137  * with eager rdma
138  * connections
139  */
140  int32_t udapl_async_events;
141  int32_t udapl_connect_inprogress;
142  int32_t udapl_num_peers;
143 
144  /* module specific limits */
145  int udapl_async_evd_qlen;
146  int udapl_conn_evd_qlen;
147  int udapl_dto_evd_qlen;
148  int udapl_max_request_dtos; /**< maximum number of outstanding consumer
149  submitted sends and rdma operations, see
150  section 6.6.6 of uDAPL Spec */
151  int udapl_max_recv_dtos; /**< maximum number of outstanding consumer
152  submitted recv operations, see section
153  6.6.6 of uDAPL Spec */
154  uint32_t udapl_if_mask; /**< netmask value btl module */
155 };
157 extern mca_btl_udapl_module_t mca_btl_udapl_module;
158 
161  DAT_LMR_HANDLE lmr; /* local memory region (LMR) */
162  DAT_LMR_TRIPLET lmr_triplet; /* LMR triplet - context, address, length */
163  DAT_RMR_CONTEXT rmr_context; /* remote memory region context handle */
164 
165 };
167 
168 /**
169  * Report Out from uDAPL BTL
170  *
171  * - BTL_ERROR() : Use to report out errors from uDAPL BTL. These are
172  * critical errors which will most likely cause the program to fail so
173  * this message should always be reported to the user. Defined in
174  * btl/base/btl_base_error.h.
175  * Example:
176  * dat_strerror(rc, (const char**)&major, (const char**)&minor);
177  * BTL_ERROR(("ERROR: %s %s %s\n", "dat_cr_accept", major, minor));
178  *
179  * - BTL_UDAPL_VERBOSE_OUTPUT() : Use to output different levels
180  * of verbosity to the user. See Note below.
181  * Example:
182  * BTL_UDAPL_VERBOSE_OUTPUT(VERBOSE_DIAGNOSE,
183  * ("WARNING: don't %s", "jump"));
184  *
185  * - BTL_UDAPL_VERBOSE_HELP() : Use output information as defined in
186  * uDAPL BTL help file (help-mpi-btl-udapl.txt). See Note below.
187  * Example:
188  * BTL_UDAPL_VERBOSE_HELP(VERBOSE_SHOW_HELP,
189  * ("help-mpi-btl-udapl.txt",
190  * "invalid num rdma segments", true, 22));
191  *
192  * Note : - Verbose levels are defined below. These levels are
193  * controlled by the mca parameter "btl_udapl_verbose".
194  * The verbose level is set to 10 by default so that critical
195  * error and useful help information will appear. Which ever value
196  * this param is set to, those messages as well as any lower level
197  * verbose messages will be reported.
198  * - Setting "btl_udapl_verbose" to "-1" will turn off all
199  * messages reported by the use of BTL_UDAPL_VERBOSE_*().
200  * - These macros should not be used in a critical path as they
201  * are always included in the compiled code.
202  * - These macros rely on the use of paranthesis around the "args"
203  * value.
204  *
205  * Values used with BTL_UDAPL_VERBOSE_*():
206  *
207  * - 0: critical user information; should always be reported;
208  * on by default
209  * - 10: useful help messages that would be reported from
210  * "help-mpi-btl-udapl.txt"; accessed from
211  * BTL_UDAPL_VERBOSE_HELP(); on by default
212  * - 20: general execution diagnostic information;
213  * may be useful to user or btl developer
214  * - 30: basic debugging/diagnostic information
215  * - 90: useful only to developers
216  * - 100: other components do not appear to go beyond 100 for verbose
217  * levels so noting here as the max for future reference
218  */
219 #define VERBOSE_CRITICAL 0
220 #define VERBOSE_SHOW_HELP 10
221 #define VERBOSE_INFORM 20
222 #define VERBOSE_DIAGNOSE 30
223 #define VERBOSE_DEVELOPER 90
224 
225 #define BTL_UDAPL_VERBOSE_OUTPUT(verbose_level, args) \
226 do { \
227  if (verbose_level <= mca_btl_udapl_component.udapl_verbosity) { \
228  BTL_OUTPUT(args); \
229  } \
230 } while(0);
231 
232 #define BTL_UDAPL_VERBOSE_HELP(verbose_level, args) \
233 do { \
234  if (verbose_level <= mca_btl_udapl_component.udapl_verbosity) { \
235  orte_show_help args; \
236  } \
237 } while(0);
238 
239 
240 /*
241  * Report a uDAPL error - for debugging
242  */
243 
244 #if OPAL_ENABLE_DEBUG
245 extern void mca_btl_udapl_error(DAT_RETURN ret, char* str);
246 
247 #define MCA_BTL_UDAPL_ERROR(ret, str) \
248  mca_btl_udapl_error((ret), (str));
249 
250 #else
251 #define MCA_BTL_UDAPL_ERROR(ret, str)
252 #endif
253 
254 
255 /**
256  * Register uDAPL component parameters with the MCA framework
257  */
258 extern int mca_btl_udapl_component_open(void);
259 
260 /**
261  * Any final cleanup before being unloaded.
262  */
263 extern int mca_btl_udapl_component_close(void);
264 
265 /**
266  * uDAPL component initialization.
267  *
268  * @param num_btl_modules (OUT) Number of BTLs returned in BTL array.
269  * @param allow_multi_user_threads (OUT) Flag indicating wether BTL supports user threads (TRUE)
270  * @param have_hidden_threads (OUT) Flag indicating wether BTL uses threads (TRUE)
271  */
273  int *num_btl_modules,
274  bool allow_multi_user_threads,
275  bool have_hidden_threads
276 );
277 
278 
279 /**
280  * uDAPL component progress.
281  */
282 
283 extern int mca_btl_udapl_component_progress(void);
284 
285 
286 /**
287  * Initialize resources for a new BTL/uDAPL IA
288  *
289  * @param ia_name Name of uDAPL interface adapter
290  * @param btl BTL instance.
291  * @return OMPI_SUCCESS or error status on failure.
292  */
293 
294 extern int mca_btl_udapl_init(
295  DAT_NAME_PTR ia_name,
296  struct mca_btl_udapl_module_t* btl
297 );
298 
299 
300 /**
301  * Cleanup any resources held by the BTL.
302  *
303  * @param btl BTL instance.
304  * @return OMPI_SUCCESS or error status on failure.
305  */
306 
307 extern int mca_btl_udapl_finalize(
308  struct mca_btl_base_module_t* btl
309 );
310 
311 
312 /**
313  * PML->BTL notification of change in the process list.
314  *
315  * @param btl (IN)
316  * @param nprocs (IN) Number of processes
317  * @param procs (IN) Set of processes
318  * @param peers (OUT) Set of (optional) peer addressing info.
319  * @param peers (IN/OUT) Set of processes that are reachable via this BTL.
320  * @return OMPI_SUCCESS or error status on failure.
321  *
322  */
323 
324 extern int mca_btl_udapl_add_procs(
325  struct mca_btl_base_module_t* btl,
326  size_t nprocs,
327  struct ompi_proc_t **procs,
328  struct mca_btl_base_endpoint_t** peers,
329  opal_bitmap_t* reachable
330 );
331 
332 /**
333  * PML->BTL notification of change in the process list.
334  *
335  * @param btl (IN) BTL instance
336  * @param nproc (IN) Number of processes.
337  * @param procs (IN) Set of processes.
338  * @param peers (IN) Set of peer data structures.
339  * @return Status indicating if cleanup was successful
340  *
341  */
342 
343 extern int mca_btl_udapl_del_procs(
344  struct mca_btl_base_module_t* btl,
345  size_t nprocs,
346  struct ompi_proc_t **procs,
347  struct mca_btl_base_endpoint_t** peers
348 );
349 
350 
351 /**
352  * Initiate an asynchronous send.
353  *
354  * @param btl (IN) BTL module
355  * @param endpoint (IN) BTL addressing information
356  * @param descriptor (IN) Description of the data to be transferred
357  * @param tag (IN) The tag value used to notify the peer.
358  */
359 
360 extern int mca_btl_udapl_send(
361  struct mca_btl_base_module_t* btl,
362  struct mca_btl_base_endpoint_t* btl_peer,
363  struct mca_btl_base_descriptor_t* descriptor,
364  mca_btl_base_tag_t tag
365 );
366 
367 
368 /**
369  * Initiate an asynchronous put.
370  *
371  * @param btl (IN) BTL module
372  * @param endpoint (IN) BTL addressing information
373  * @param descriptor (IN) Description of the data to be transferred
374  */
375 
376 extern int mca_btl_udapl_put(
377  struct mca_btl_base_module_t* btl,
378  struct mca_btl_base_endpoint_t* btl_peer,
379  struct mca_btl_base_descriptor_t* decriptor
380 );
381 
382 
383 /**
384  * Initiate an asynchronous get.
385  *
386  * @param btl (IN) BTL module
387  * @param endpoint (IN) BTL addressing information
388  * @param descriptor (IN) Description of the data to be transferred
389  */
390 
391 extern int mca_btl_udapl_get(
392  struct mca_btl_base_module_t* btl,
393  struct mca_btl_base_endpoint_t* btl_peer,
394  struct mca_btl_base_descriptor_t* decriptor
395 );
396 
397 /**
398  * Allocate a descriptor with a segment of the requested size.
399  * Note that the BTL layer may choose to return a smaller size
400  * if it cannot support the request.
401  *
402  * @param btl (IN) BTL module
403  * @param size (IN) Request segment size.
404  */
405 
407  struct mca_btl_base_module_t* btl,
408  struct mca_btl_base_endpoint_t* endpoint,
409  uint8_t order,
410  size_t size,
411  uint32_t flags);
412 
413 
414 /**
415  * Return a segment allocated by this BTL.
416  *
417  * @param btl (IN) BTL module
418  * @param descriptor (IN) Allocated descriptor.
419  */
420 
421 extern int mca_btl_udapl_free(
422  struct mca_btl_base_module_t* btl,
424 
425 
426 /**
427  * Prepare a descriptor for send/rdma using the supplied
428  * convertor. If the convertor references data that is contigous,
429  * the descriptor may simply point to the user buffer. Otherwise,
430  * this routine is responsible for allocating buffer space and
431  * packing if required.
432  *
433  * @param btl (IN) BTL module
434  * @param endpoint (IN) BTL peer addressing
435  * @param convertor (IN) Data type convertor
436  * @param reserve (IN) Additional bytes requested by upper layer to precede user data
437  * @param size (IN/OUT) Number of bytes to prepare (IN), number of bytes actually prepared (OUT)
438 */
439 
441  struct mca_btl_base_module_t* btl,
442  struct mca_btl_base_endpoint_t* peer,
444  struct opal_convertor_t* convertor,
445  uint8_t order,
446  size_t reserve,
447  size_t* size,
448  uint32_t flags
449 );
450 
452  struct mca_btl_base_module_t* btl,
453  struct mca_btl_base_endpoint_t* peer,
455  struct opal_convertor_t* convertor,
456  uint8_t order,
457  size_t reserve,
458  size_t* size,
459  uint32_t flags);
460 
461  /**
462  * Fault Tolerance Event Notification Function
463  * @param state Checkpoint Stae
464  * @return OMPI_SUCCESS or failure status
465  */
466 int mca_btl_udapl_ft_event(int state);
467 
468 END_C_DECLS
469 #endif
int mca_btl_udapl_component_close(void)
Any final cleanup before being unloaded.
Definition: btl_udapl_component.c:225
int mca_btl_udapl_get(struct mca_btl_base_module_t *btl, struct mca_btl_base_endpoint_t *btl_peer, struct mca_btl_base_descriptor_t *decriptor)
Initiate an asynchronous get.
Definition: btl_udapl.c:1318
int mca_btl_udapl_ft_event(int state)
Fault Tolerance Event Notification Function.
Definition: btl_udapl.c:1327
int32_t udapl_eager_rdma_num
number of rdma buffers allocated for short messages
Definition: btl_udapl.h:75
opal_mutex_t udapl_lock
lock for accessing module state
Definition: btl_udapl.h:87
Populates global structure with system-specific information.
A descriptor that holds the parameters to a send/put/get operation along w/ a callback routine that i...
Definition: btl.h:275
dynamic pointer array
Definition: opal_pointer_array.h:45
Definition: opal_bitmap.h:53
int32_t udapl_sr_win
number of fragments recieved before returning credits to sender
Definition: btl_udapl.h:62
mca_btl_base_descriptor_t * mca_btl_udapl_prepare_dst(struct mca_btl_base_module_t *btl, struct mca_btl_base_endpoint_t *peer, struct mca_mpool_base_registration_t *, struct opal_convertor_t *convertor, uint8_t order, size_t reserve, size_t *size, uint32_t flags)
Prepare a descriptor for send/rdma using the supplied convertor.
Definition: btl_udapl.c:1149
mca_btl_base_descriptor_t * mca_btl_udapl_prepare_src(struct mca_btl_base_module_t *btl, struct mca_btl_base_endpoint_t *peer, struct mca_mpool_base_registration_t *, struct opal_convertor_t *convertor, uint8_t order, size_t reserve, size_t *size, uint32_t flags)
Prepare a descriptor for send/rdma using the supplied convertor.
Definition: btl_udapl.c:1019
mca_btl_base_component_2_0_0_t super
base BTL component
Definition: btl_udapl.h:53
struct mca_btl_udapl_module_t ** udapl_btls
array of available BTL modules
Definition: btl_udapl.h:59
int32_t udapl_max_eager_rdma_peers
maximum number of peers allowed to use RDMA for short messages (cap)
Definition: btl_udapl.h:77
Definition: mutex_unix.h:53
int mca_btl_udapl_send(struct mca_btl_base_module_t *btl, struct mca_btl_base_endpoint_t *btl_peer, struct mca_btl_base_descriptor_t *descriptor, mca_btl_base_tag_t tag)
Initiate an asynchronous send.
Definition: btl_udapl.c:1209
int32_t udapl_num_sends
number of sends to post on endpoint
Definition: btl_udapl.h:61
Structure used to publish uDAPL id information to peers.
Definition: btl_udapl_endpoint.h:50
int mca_btl_udapl_add_procs(struct mca_btl_base_module_t *btl, size_t nprocs, struct ompi_proc_t **procs, struct mca_btl_base_endpoint_t **peers, opal_bitmap_t *reachable)
PML->BTL notification of change in the process list.
Definition: btl_udapl.c:854
Definition: mpool.h:44
See opal_bitmap.h for an explanation of why there is a split between OPAL and ORTE for this generic c...
Remote Open MPI process structure.
Definition: proc.h:56
int udapl_free_list_inc
number of elements to alloc when growing
Definition: btl_udapl.h:73
uint32_t udapl_if_mask
netmask value btl module
Definition: btl_udapl.h:154
int mca_btl_udapl_free(struct mca_btl_base_module_t *btl, mca_btl_base_descriptor_t *des)
Return a segment allocated by this BTL.
Definition: btl_udapl.c:987
int udapl_free_list_max
maximum size of free lists
Definition: btl_udapl.h:72
int32_t udapl_buffer_alignment
preferred communication buffer alignment, in bytes
Definition: btl_udapl.h:85
int mca_btl_udapl_put(struct mca_btl_base_module_t *btl, struct mca_btl_base_endpoint_t *btl_peer, struct mca_btl_base_descriptor_t *decriptor)
Initiate an asynchronous put.
Definition: btl_udapl.c:1238
int32_t udapl_verbosity
report out level, see "Report Out from uDAPL BTL" below for details.
Definition: btl_udapl.h:55
uDAPL BTL component.
Definition: btl_udapl.h:52
int mca_btl_udapl_finalize(struct mca_btl_base_module_t *btl)
Cleanup any resources held by the BTL.
Definition: btl_udapl.c:496
int32_t udapl_use_eager_rdma
turn rdma for small msgs on/off
Definition: btl_udapl.h:74
mca_btl_base_module_t super
base BTL interface
Definition: btl_udapl.h:107
Definition: btl_udapl.h:159
int mca_btl_udapl_component_open(void)
Register uDAPL component parameters with the MCA framework.
Definition: btl_udapl_component.c:185
mca_btl_base_descriptor_t * mca_btl_udapl_alloc(struct mca_btl_base_module_t *btl, struct mca_btl_base_endpoint_t *endpoint, uint8_t order, size_t size, uint32_t flags)
Allocate a descriptor with a segment of the requested size.
Definition: btl_udapl.c:929
Byte Transfer Layer (BTL)
BTL Module Interface.
Definition: btl_udapl.h:106
uint32_t udapl_timeout
connection timeout, in microseconds
Definition: btl_udapl.h:64
Definition: ompi_free_list.h:39
mca_btl_base_module_t ** mca_btl_udapl_component_init(int *num_btl_modules, bool allow_multi_user_threads, bool have_hidden_threads)
uDAPL component initialization.
Definition: btl_udapl_component.c:436
opal_list_t udapl_procs
list of udapl proc structures
Definition: btl_udapl.h:86
int mca_btl_udapl_init(DAT_NAME_PTR ia_name, struct mca_btl_udapl_module_t *btl)
Initialize resources for a new BTL/uDAPL IA.
Definition: btl_udapl.c:145
State of ELAN endpoint connection.
Definition: btl_elan_endpoint.h:33
BTL component descriptor.
Definition: btl.h:411
Copyright (c) 2004-2007 The Trustees of Indiana University and Indiana University Research and Techno...
Definition: opal_convertor.h:90
int udapl_free_list_num
initial size of free lists
Definition: btl_udapl.h:71
Definition: opal_list.h:147
int mca_btl_udapl_del_procs(struct mca_btl_base_module_t *btl, size_t nprocs, struct ompi_proc_t **procs, struct mca_btl_base_endpoint_t **peers)
PML->BTL notification of change in the process list.
Definition: btl_udapl.c:912
int32_t udapl_conn_priv_data
use connect priv data for proc data
Definition: btl_udapl.h:83
int32_t udapl_num_recvs
number of recv buffers to keep posted
Definition: btl_udapl.h:60
int mca_btl_udapl_component_progress(void)
uDAPL component progress.
Definition: btl_udapl_component.c:834
size_t udapl_max_btls
maximum number of supported hcas
Definition: btl_udapl.h:58
int udapl_max_recv_dtos
maximum number of outstanding consumer submitted recv operations, see section 6.6.6 of uDAPL Spec
Definition: btl_udapl.h:151
int32_t udapl_async_events
dequeue asynchronous events
Definition: btl_udapl.h:84
int32_t udapl_eager_rdma_win
number of eager RDMA fragments recieved before returning credits to sender
Definition: btl_udapl.h:80
BTL module interface functions and attributes.
Definition: btl.h:786
char * udapl_mpool_name
name of memory pool
Definition: btl_udapl.h:88
int udapl_max_request_dtos
maximum number of outstanding consumer submitted sends and rdma operations, see section 6...
Definition: btl_udapl.h:148
int32_t udapl_compare_subnet
whether to compare with netmask or not
Definition: btl_udapl.h:89
size_t udapl_num_btls
number of hcas available to the uDAPL component
Definition: btl_udapl.h:57