Actual source code: mpishm.c
1: #include <petscsys.h>
2: #include <petsc/private/petscimpl.h>
4: struct _n_PetscShmComm {
5: PetscMPIInt *globranks; /* global ranks of each rank in the shared memory communicator */
6: PetscMPIInt shmsize; /* size of the shared memory communicator */
7: MPI_Comm globcomm,shmcomm; /* global communicator and shared memory communicator (a sub-communicator of the former) */
8: };
10: /*
11: Private routine to delete internal shared memory communicator when a communicator is freed.
13: This is called by MPI, not by users. This is called by MPI_Comm_free() when the communicator that has this data as an attribute is freed.
15: Note: this is declared extern "C" because it is passed to MPI_Comm_create_keyval()
17: */
18: PETSC_EXTERN PetscMPIInt MPIAPI Petsc_ShmComm_Attr_Delete_Fn(MPI_Comm comm,PetscMPIInt keyval,void *val,void *extra_state)
19: {
20: PetscErrorCode ierr;
21: PetscShmComm p = (PetscShmComm)val;
24: PetscInfo1(NULL,"Deleting shared memory subcommunicator in a MPI_Comm %ld\n",(long)comm);
25: MPI_Comm_free(&p->shmcomm);
26: PetscFree(p->globranks);
27: PetscFree(val);
28: PetscFunctionReturn(MPI_SUCCESS);
29: }
31: /*@C
32: PetscShmCommGet - Given a PETSc communicator returns a communicator of all ranks that share a common memory
35: Collective.
37: Input Parameter:
38: . globcomm - MPI_Comm
40: Output Parameter:
41: . pshmcomm - the PETSc shared memory communicator object
43: Level: developer
45: Notes:
46: This should be called only with an PetscCommDuplicate() communictor
48: When used with MPICH, MPICH must be configured with --download-mpich-device=ch3:nemesis
50: @*/
51: PetscErrorCode PetscShmCommGet(MPI_Comm globcomm,PetscShmComm *pshmcomm)
52: {
53: #ifdef PETSC_HAVE_MPI_PROCESS_SHARED_MEMORY
54: PetscErrorCode ierr;
55: MPI_Group globgroup,shmgroup;
56: PetscMPIInt *shmranks,i,flg;
57: PetscCommCounter *counter;
60: MPI_Comm_get_attr(globcomm,Petsc_Counter_keyval,&counter,&flg);
61: if (!flg) SETERRQ(globcomm,PETSC_ERR_ARG_CORRUPT,"Bad MPI communicator supplied; must be a PETSc communicator");
63: MPI_Comm_get_attr(globcomm,Petsc_ShmComm_keyval,pshmcomm,&flg);
64: if (flg) return(0);
66: PetscNew(pshmcomm);
67: (*pshmcomm)->globcomm = globcomm;
69: MPI_Comm_split_type(globcomm, MPI_COMM_TYPE_SHARED,0, MPI_INFO_NULL,&(*pshmcomm)->shmcomm);
71: MPI_Comm_size((*pshmcomm)->shmcomm,&(*pshmcomm)->shmsize);
72: MPI_Comm_group(globcomm, &globgroup);
73: MPI_Comm_group((*pshmcomm)->shmcomm, &shmgroup);
74: PetscMalloc1((*pshmcomm)->shmsize,&shmranks);
75: PetscMalloc1((*pshmcomm)->shmsize,&(*pshmcomm)->globranks);
76: for (i=0; i<(*pshmcomm)->shmsize; i++) shmranks[i] = i;
77: MPI_Group_translate_ranks(shmgroup, (*pshmcomm)->shmsize, shmranks, globgroup, (*pshmcomm)->globranks);
78: PetscFree(shmranks);
79: MPI_Group_free(&globgroup);
80: MPI_Group_free(&shmgroup);
82: for (i=0; i<(*pshmcomm)->shmsize; i++) {
83: PetscInfo2(NULL,"Shared memory rank %d global rank %d\n",i,(*pshmcomm)->globranks[i]);
84: }
85: MPI_Comm_set_attr(globcomm,Petsc_ShmComm_keyval,*pshmcomm);
86: return(0);
87: #else
88: SETERRQ(globcomm, PETSC_ERR_SUP, "Shared memory communicators need MPI-3 package support.\nPlease upgrade your MPI or reconfigure with --download-mpich.");
89: #endif
90: }
92: /*@C
93: PetscShmCommGlobalToLocal - Given a global rank returns the local rank in the shared memory communicator
95: Input Parameters:
96: + pshmcomm - the shared memory communicator object
97: - grank - the global rank
99: Output Parameter:
100: . lrank - the local rank, or MPI_PROC_NULL if it does not exist
102: Level: developer
104: Developer Notes:
105: Assumes the pshmcomm->globranks[] is sorted
107: It may be better to rewrite this to map multiple global ranks to local in the same function call
109: @*/
110: PetscErrorCode PetscShmCommGlobalToLocal(PetscShmComm pshmcomm,PetscMPIInt grank,PetscMPIInt *lrank)
111: {
112: PetscMPIInt low,high,t,i;
113: PetscBool flg = PETSC_FALSE;
117: *lrank = MPI_PROC_NULL;
118: if (grank < pshmcomm->globranks[0]) return(0);
119: if (grank > pshmcomm->globranks[pshmcomm->shmsize-1]) return(0);
120: PetscOptionsGetBool(NULL,NULL,"-noshared",&flg,NULL);
121: if (flg) return(0);
122: low = 0;
123: high = pshmcomm->shmsize;
124: while (high-low > 5) {
125: t = (low+high)/2;
126: if (pshmcomm->globranks[t] > grank) high = t;
127: else low = t;
128: }
129: for (i=low; i<high; i++) {
130: if (pshmcomm->globranks[i] > grank) return(0);
131: if (pshmcomm->globranks[i] == grank) {
132: *lrank = i;
133: return(0);
134: }
135: }
136: return(0);
137: }
139: /*@C
140: PetscShmCommLocalToGlobal - Given a local rank in the shared memory communicator returns the global rank
142: Input Parameters:
143: + pshmcomm - the shared memory communicator object
144: - lrank - the local rank in the shared memory communicator
146: Output Parameter:
147: . grank - the global rank in the global communicator where the shared memory communicator is built
149: Level: developer
151: @*/
152: PetscErrorCode PetscShmCommLocalToGlobal(PetscShmComm pshmcomm,PetscMPIInt lrank,PetscMPIInt *grank)
153: {
155: if (lrank < 0 || lrank >= pshmcomm->shmsize) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"No rank %D in the shared memory communicator",lrank);
156: *grank = pshmcomm->globranks[lrank];
157: return(0);
158: }
160: /*@C
161: PetscShmCommGetMpiShmComm - Returns the MPI communicator that represents all processes with common shared memory
163: Input Parameter:
164: . pshmcomm - PetscShmComm object obtained with PetscShmCommGet()
166: Output Parameter:
167: . comm - the MPI communicator
169: Level: developer
171: @*/
172: PetscErrorCode PetscShmCommGetMpiShmComm(PetscShmComm pshmcomm,MPI_Comm *comm)
173: {
175: *comm = pshmcomm->shmcomm;
176: return(0);
177: }
179: #if defined(PETSC_HAVE_OPENMP_SUPPORT)
180: #include <pthread.h>
181: #include <hwloc.h>
182: #include <omp.h>
184: /* Use mmap() to allocate shared mmeory (for the pthread_barrier_t object) if it is available,
185: otherwise use MPI_Win_allocate_shared. They should have the same effect except MPI-3 is much
186: simpler to use. However, on a Cori Haswell node with Cray MPI, MPI-3 worsened a test's performance
187: by 50%. Until the reason is found out, we use mmap() instead.
188: */
189: #define USE_MMAP_ALLOCATE_SHARED_MEMORY
191: #if defined(USE_MMAP_ALLOCATE_SHARED_MEMORY) && defined(PETSC_HAVE_MMAP)
192: #include <sys/mman.h>
193: #include <sys/types.h>
194: #include <sys/stat.h>
195: #include <fcntl.h>
196: #endif
198: struct _n_PetscOmpCtrl {
199: MPI_Comm omp_comm; /* a shared memory communicator to spawn omp threads */
200: MPI_Comm omp_master_comm; /* a communicator to give to third party libraries */
201: PetscMPIInt omp_comm_size; /* size of omp_comm, a kind of OMP_NUM_THREADS */
202: PetscBool is_omp_master; /* rank 0's in omp_comm */
203: MPI_Win omp_win; /* a shared memory window containing a barrier */
204: pthread_barrier_t *barrier; /* pointer to the barrier */
205: hwloc_topology_t topology;
206: hwloc_cpuset_t cpuset; /* cpu bindings of omp master */
207: hwloc_cpuset_t omp_cpuset; /* union of cpu bindings of ranks in omp_comm */
208: };
211: /* Allocate and initialize a pthread_barrier_t object in memory shared by processes in omp_comm
212: contained by the controller.
214: PETSc OpenMP controller users do not call this function directly. This function exists
215: only because we want to separate shared memory allocation methods from other code.
216: */
217: PETSC_STATIC_INLINE PetscErrorCode PetscOmpCtrlCreateBarrier(PetscOmpCtrl ctrl)
218: {
219: PetscErrorCode ierr;
220: MPI_Aint size;
221: void *baseptr;
222: pthread_barrierattr_t attr;
224: #if defined(USE_MMAP_ALLOCATE_SHARED_MEMORY) && defined(PETSC_HAVE_MMAP)
225: PetscInt fd;
226: PetscChar pathname[PETSC_MAX_PATH_LEN];
227: #else
228: PetscMPIInt disp_unit;
229: #endif
232: #if defined(USE_MMAP_ALLOCATE_SHARED_MEMORY) && defined(PETSC_HAVE_MMAP)
233: size = sizeof(pthread_barrier_t);
234: if (ctrl->is_omp_master) {
235: /* use PETSC_COMM_SELF in PetscGetTmp, since it is a collective call. Using omp_comm would otherwise bcast the partially populated pathname to slaves */
236: PetscGetTmp(PETSC_COMM_SELF,pathname,PETSC_MAX_PATH_LEN);
237: PetscStrlcat(pathname,"/petsc-shm-XXXXXX",PETSC_MAX_PATH_LEN);
238: /* mkstemp replaces XXXXXX with a unique file name and opens the file for us */
239: fd = mkstemp(pathname); if (fd == -1) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Could not create tmp file %s with mkstemp\n", pathname);
240: ftruncate(fd,size);
241: baseptr = mmap(NULL,size,PROT_READ | PROT_WRITE, MAP_SHARED,fd,0); if (baseptr == MAP_FAILED) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_LIB,"mmap() failed\n");
242: close(fd);
243: MPI_Bcast(pathname,PETSC_MAX_PATH_LEN,MPI_CHAR,0,ctrl->omp_comm);
244: /* this MPI_Barrier is to wait slaves to open the file before master unlinks it */
245: MPI_Barrier(ctrl->omp_comm);
246: unlink(pathname);
247: } else {
248: MPI_Bcast(pathname,PETSC_MAX_PATH_LEN,MPI_CHAR,0,ctrl->omp_comm);
249: fd = open(pathname,O_RDWR); if (fd == -1) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Could not open tmp file %s\n", pathname);
250: baseptr = mmap(NULL,size,PROT_READ | PROT_WRITE, MAP_SHARED,fd,0); if (baseptr == MAP_FAILED) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_LIB,"mmap() failed\n");
251: close(fd);
252: MPI_Barrier(ctrl->omp_comm);
253: }
254: #else
255: size = ctrl->is_omp_master ? sizeof(pthread_barrier_t) : 0;
256: MPI_Win_allocate_shared(size,1,MPI_INFO_NULL,ctrl->omp_comm,&baseptr,&ctrl->omp_win);
257: MPI_Win_shared_query(ctrl->omp_win,0,&size,&disp_unit,&baseptr);
258: #endif
259: ctrl->barrier = (pthread_barrier_t*)baseptr;
261: /* omp master initializes the barrier */
262: if (ctrl->is_omp_master) {
263: MPI_Comm_size(ctrl->omp_comm,&ctrl->omp_comm_size);
264: pthread_barrierattr_init(&attr);
265: pthread_barrierattr_setpshared(&attr,PTHREAD_PROCESS_SHARED); /* make the barrier also work for processes */
266: pthread_barrier_init(ctrl->barrier,&attr,(unsigned int)ctrl->omp_comm_size);
267: pthread_barrierattr_destroy(&attr);
268: }
270: /* this MPI_Barrier is to make sure the omp barrier is initialized before slaves use it */
271: MPI_Barrier(ctrl->omp_comm);
272: return(0);
273: }
275: /* Destroy the pthread barrier in the PETSc OpenMP controller */
276: PETSC_STATIC_INLINE PetscErrorCode PetscOmpCtrlDestroyBarrier(PetscOmpCtrl ctrl)
277: {
281: /* this MPI_Barrier is to make sure slaves have finished using the omp barrier before master destroys it */
282: MPI_Barrier(ctrl->omp_comm);
283: if (ctrl->is_omp_master) { pthread_barrier_destroy(ctrl->barrier); }
285: #if defined(USE_MMAP_ALLOCATE_SHARED_MEMORY) && defined(PETSC_HAVE_MMAP)
286: munmap(ctrl->barrier,sizeof(pthread_barrier_t));
287: #else
288: MPI_Win_free(&ctrl->omp_win);
289: #endif
290: return(0);
291: }
293: /*@C
294: PetscOmpCtrlCreate - create a PETSc OpenMP controller, which manages PETSc's interaction with third party libraries using OpenMP
296: Input Parameter:
297: + petsc_comm - a communicator some PETSc object (for example, a matrix) lives in
298: - nthreads - number of threads per MPI rank to spawn in a library using OpenMP. If nthreads = -1, let PETSc decide a suitable value
300: Output Parameter:
301: . pctrl - a PETSc OpenMP controller
303: Level: developer
305: TODO: Possibly use the variable PetscNumOMPThreads to determine the number for threads to use
307: .seealso PetscOmpCtrlDestroy()
308: @*/
309: PetscErrorCode PetscOmpCtrlCreate(MPI_Comm petsc_comm,PetscInt nthreads,PetscOmpCtrl *pctrl)
310: {
311: PetscErrorCode ierr;
312: PetscOmpCtrl ctrl;
313: unsigned long *cpu_ulongs=NULL;
314: PetscInt i,nr_cpu_ulongs;
315: PetscShmComm pshmcomm;
316: MPI_Comm shm_comm;
317: PetscMPIInt shm_rank,shm_comm_size,omp_rank,color;
318: PetscInt num_packages,num_cores;
321: PetscNew(&ctrl);
323: /*=================================================================================
324: Init hwloc
325: ==================================================================================*/
326: hwloc_topology_init(&ctrl->topology);
327: #if HWLOC_API_VERSION >= 0x00020000
328: /* to filter out unneeded info and have faster hwloc_topology_load */
329: hwloc_topology_set_all_types_filter(ctrl->topology,HWLOC_TYPE_FILTER_KEEP_NONE);
330: hwloc_topology_set_type_filter(ctrl->topology,HWLOC_OBJ_CORE,HWLOC_TYPE_FILTER_KEEP_ALL);
331: #endif
332: hwloc_topology_load(ctrl->topology);
334: /*=================================================================================
335: Split petsc_comm into multiple omp_comms. Ranks in an omp_comm have access to
336: physically shared memory. Rank 0 of each omp_comm is called an OMP master, and
337: others are called slaves. OMP Masters make up a new comm called omp_master_comm,
338: which is usually passed to third party libraries.
339: ==================================================================================*/
341: /* fetch the stored shared memory communicator */
342: PetscShmCommGet(petsc_comm,&pshmcomm);
343: PetscShmCommGetMpiShmComm(pshmcomm,&shm_comm);
345: MPI_Comm_rank(shm_comm,&shm_rank);
346: MPI_Comm_size(shm_comm,&shm_comm_size);
348: /* PETSc decides nthreads, which is the smaller of shm_comm_size or cores per package(socket) */
349: if (nthreads == -1) {
350: num_packages = hwloc_get_nbobjs_by_type(ctrl->topology,HWLOC_OBJ_PACKAGE) <= 0 ? 1 : hwloc_get_nbobjs_by_type(ctrl->topology,HWLOC_OBJ_PACKAGE);
351: num_cores = hwloc_get_nbobjs_by_type(ctrl->topology,HWLOC_OBJ_CORE) <= 0 ? 1 : hwloc_get_nbobjs_by_type(ctrl->topology,HWLOC_OBJ_CORE);
352: nthreads = num_cores/num_packages;
353: if (nthreads > shm_comm_size) nthreads = shm_comm_size;
354: }
356: if (nthreads < 1 || nthreads > shm_comm_size) SETERRQ2(petsc_comm,PETSC_ERR_ARG_OUTOFRANGE,"number of OpenMP threads %D can not be < 1 or > the MPI shared memory communicator size %d\n",nthreads,shm_comm_size);
357: if (shm_comm_size % nthreads) { PetscPrintf(petsc_comm,"Warning: number of OpenMP threads %D is not a factor of the MPI shared memory communicator size %d, which may cause load-imbalance!\n",nthreads,shm_comm_size); }
359: /* split shm_comm into a set of omp_comms with each of size nthreads. Ex., if
360: shm_comm_size=16, nthreads=8, then ranks 0~7 get color 0 and ranks 8~15 get
361: color 1. They are put in two omp_comms. Note that petsc_ranks may or may not
362: be consecutive in a shm_comm, but shm_ranks always run from 0 to shm_comm_size-1.
363: Use 0 as key so that rank ordering wont change in new comm.
364: */
365: color = shm_rank / nthreads;
366: MPI_Comm_split(shm_comm,color,0/*key*/,&ctrl->omp_comm);
368: /* put rank 0's in omp_comms (i.e., master ranks) into a new comm - omp_master_comm */
369: MPI_Comm_rank(ctrl->omp_comm,&omp_rank);
370: if (!omp_rank) {
371: ctrl->is_omp_master = PETSC_TRUE; /* master */
372: color = 0;
373: } else {
374: ctrl->is_omp_master = PETSC_FALSE; /* slave */
375: color = MPI_UNDEFINED; /* to make slaves get omp_master_comm = MPI_COMM_NULL in MPI_Comm_split */
376: }
377: MPI_Comm_split(petsc_comm,color,0/*key*/,&ctrl->omp_master_comm);
379: /*=================================================================================
380: Each omp_comm has a pthread_barrier_t in its shared memory, which is used to put
381: slave ranks in sleep and idle their CPU, so that the master can fork OMP threads
382: and run them on the idle CPUs.
383: ==================================================================================*/
384: PetscOmpCtrlCreateBarrier(ctrl);
386: /*=================================================================================
387: omp master logs its cpu binding (i.e., cpu set) and computes a new binding that
388: is the union of the bindings of all ranks in the omp_comm
389: =================================================================================*/
391: ctrl->cpuset = hwloc_bitmap_alloc(); if (!ctrl->cpuset) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_LIB,"hwloc_bitmap_alloc() failed\n");
392: hwloc_get_cpubind(ctrl->topology,ctrl->cpuset, HWLOC_CPUBIND_PROCESS);
394: /* hwloc main developer said they will add new APIs hwloc_bitmap_{nr,to,from}_ulongs in 2.1 to help us simplify the following bitmap pack/unpack code */
395: nr_cpu_ulongs = (hwloc_bitmap_last(hwloc_topology_get_topology_cpuset (ctrl->topology))+sizeof(unsigned long)*8)/sizeof(unsigned long)/8;
396: PetscMalloc1(nr_cpu_ulongs,&cpu_ulongs);
397: if (nr_cpu_ulongs == 1) {
398: cpu_ulongs[0] = hwloc_bitmap_to_ulong(ctrl->cpuset);
399: } else {
400: for (i=0; i<nr_cpu_ulongs; i++) cpu_ulongs[i] = hwloc_bitmap_to_ith_ulong(ctrl->cpuset,(unsigned)i);
401: }
403: MPI_Reduce(ctrl->is_omp_master ? MPI_IN_PLACE : cpu_ulongs, cpu_ulongs,nr_cpu_ulongs, MPI_UNSIGNED_LONG,MPI_BOR,0,ctrl->omp_comm);
405: if (ctrl->is_omp_master) {
406: ctrl->omp_cpuset = hwloc_bitmap_alloc(); if (!ctrl->omp_cpuset) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_LIB,"hwloc_bitmap_alloc() failed\n");
407: if (nr_cpu_ulongs == 1) {
408: #if HWLOC_API_VERSION >= 0x00020000
409: hwloc_bitmap_from_ulong(ctrl->omp_cpuset,cpu_ulongs[0]);
410: #else
411: hwloc_bitmap_from_ulong(ctrl->omp_cpuset,cpu_ulongs[0]);
412: #endif
413: } else {
414: for (i=0; i<nr_cpu_ulongs; i++) {
415: #if HWLOC_API_VERSION >= 0x00020000
416: hwloc_bitmap_set_ith_ulong(ctrl->omp_cpuset,(unsigned)i,cpu_ulongs[i]);
417: #else
418: hwloc_bitmap_set_ith_ulong(ctrl->omp_cpuset,(unsigned)i,cpu_ulongs[i]);
419: #endif
420: }
421: }
422: }
424: PetscFree(cpu_ulongs);
425: *pctrl = ctrl;
426: return(0);
427: }
429: /*@C
430: PetscOmpCtrlDestroy - destroy the PETSc OpenMP controller
432: Input Parameter:
433: . pctrl - a PETSc OpenMP controller
435: Level: developer
437: .seealso PetscOmpCtrlCreate()
438: @*/
439: PetscErrorCode PetscOmpCtrlDestroy(PetscOmpCtrl *pctrl)
440: {
441: PetscErrorCode ierr;
442: PetscOmpCtrl ctrl = *pctrl;
445: hwloc_bitmap_free(ctrl->cpuset);
446: hwloc_topology_destroy(ctrl->topology);
447: PetscOmpCtrlDestroyBarrier(ctrl);
448: MPI_Comm_free(&ctrl->omp_comm);
449: if (ctrl->is_omp_master) {
450: hwloc_bitmap_free(ctrl->omp_cpuset);
451: MPI_Comm_free(&ctrl->omp_master_comm);
452: }
453: PetscFree(ctrl);
454: return(0);
455: }
457: /*@C
458: PetscOmpCtrlGetOmpComms - Get MPI communicators from a PETSc OMP controller
460: Input Parameter:
461: . ctrl - a PETSc OMP controller
463: Output Parameter:
464: + omp_comm - a communicator that includes a master rank and slave ranks where master spawns threads
465: . omp_master_comm - on master ranks, return a communicator that include master ranks of each omp_comm;
466: on slave ranks, MPI_COMM_NULL will be return in reality.
467: - is_omp_master - true if the calling process is an OMP master rank.
469: Notes: any output parameter can be NULL. The parameter is just ignored.
471: Level: developer
472: @*/
473: PetscErrorCode PetscOmpCtrlGetOmpComms(PetscOmpCtrl ctrl,MPI_Comm *omp_comm,MPI_Comm *omp_master_comm,PetscBool *is_omp_master)
474: {
476: if (omp_comm) *omp_comm = ctrl->omp_comm;
477: if (omp_master_comm) *omp_master_comm = ctrl->omp_master_comm;
478: if (is_omp_master) *is_omp_master = ctrl->is_omp_master;
479: return(0);
480: }
482: /*@C
483: PetscOmpCtrlBarrier - Do barrier on MPI ranks in omp_comm contained by the PETSc OMP controller (to let slave ranks free their CPU)
485: Input Parameter:
486: . ctrl - a PETSc OMP controller
488: Notes:
489: this is a pthread barrier on MPI processes. Using MPI_Barrier instead is conceptually correct. But MPI standard does not
490: require processes blocked by MPI_Barrier free their CPUs to let other processes progress. In practice, to minilize latency,
491: MPI processes stuck in MPI_Barrier keep polling and do not free CPUs. In contrast, pthread_barrier has this requirement.
493: A code using PetscOmpCtrlBarrier() would be like this,
495: if (is_omp_master) {
496: PetscOmpCtrlOmpRegionOnMasterBegin(ctrl);
497: Call the library using OpenMP
498: PetscOmpCtrlOmpRegionOnMasterEnd(ctrl);
499: }
500: PetscOmpCtrlBarrier(ctrl);
502: Level: developer
504: .seealso PetscOmpCtrlOmpRegionOnMasterBegin(), PetscOmpCtrlOmpRegionOnMasterEnd()
505: @*/
506: PetscErrorCode PetscOmpCtrlBarrier(PetscOmpCtrl ctrl)
507: {
508: int err;
511: err = pthread_barrier_wait(ctrl->barrier);
512: if (err && err != PTHREAD_BARRIER_SERIAL_THREAD) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"pthread_barrier_wait failed within PetscOmpCtrlBarrier with return code %D\n", err);
513: return(0);
514: }
516: /*@C
517: PetscOmpCtrlOmpRegionOnMasterBegin - Mark the beginning of an OpenMP library call on master ranks
519: Input Parameter:
520: . ctrl - a PETSc OMP controller
522: Notes:
523: Only master ranks can call this function. Call PetscOmpCtrlGetOmpComms() to know if this is a master rank.
524: This function changes CPU binding of master ranks and nthreads-var of OpenMP runtime
526: Level: developer
528: .seealso: PetscOmpCtrlOmpRegionOnMasterEnd()
529: @*/
530: PetscErrorCode PetscOmpCtrlOmpRegionOnMasterBegin(PetscOmpCtrl ctrl)
531: {
535: hwloc_set_cpubind(ctrl->topology,ctrl->omp_cpuset,HWLOC_CPUBIND_PROCESS);
536: omp_set_num_threads(ctrl->omp_comm_size); /* may override the OMP_NUM_THREAD env var */
537: return(0);
538: }
540: /*@C
541: PetscOmpCtrlOmpRegionOnMasterEnd - Mark the end of an OpenMP library call on master ranks
543: Input Parameter:
544: . ctrl - a PETSc OMP controller
546: Notes:
547: Only master ranks can call this function. Call PetscOmpCtrlGetOmpComms() to know if this is a master rank.
548: This function restores the CPU binding of master ranks and set and nthreads-var of OpenMP runtime to 1.
550: Level: developer
552: .seealso: PetscOmpCtrlOmpRegionOnMasterBegin()
553: @*/
554: PetscErrorCode PetscOmpCtrlOmpRegionOnMasterEnd(PetscOmpCtrl ctrl)
555: {
559: hwloc_set_cpubind(ctrl->topology,ctrl->cpuset,HWLOC_CPUBIND_PROCESS);
560: omp_set_num_threads(1);
561: return(0);
562: }
564: #undef USE_MMAP_ALLOCATE_SHARED_MEMORY
565: #endif /* defined(PETSC_HAVE_OPENMP_SUPPORT) */