Actual source code: shvec.c

  1: /*
  2:    This file contains routines for Parallel vector operations that use shared memory
  3:  */
  4: #include <../src/vec/vec/impls/mpi/pvecimpl.h>

  6: #if defined(PETSC_USE_SHARED_MEMORY)

  8: extern PetscErrorCode PetscSharedMalloc(MPI_Comm, PetscInt, PetscInt, void **);

 10: PetscErrorCode VecDuplicate_Shared(Vec win, Vec *v)
 11: {
 12:   Vec_MPI     *w = (Vec_MPI *)win->data;
 13:   PetscScalar *array;

 15:   PetscFunctionBegin;
 16:   /* first processor allocates entire array and sends its address to the others */
 17:   PetscCall(PetscSharedMalloc(PetscObjectComm((PetscObject)win), win->map->n * sizeof(PetscScalar), win->map->N * sizeof(PetscScalar), (void **)&array));

 19:   PetscCall(VecCreate(PetscObjectComm((PetscObject)win), v));
 20:   PetscCall(VecSetSizes(*v, win->map->n, win->map->N));
 21:   PetscCall(VecCreate_MPI_Private(*v, PETSC_FALSE, w->nghost, array));
 22:   PetscCall(PetscLayoutReference(win->map, &(*v)->map));

 24:   /* New vector should inherit stashing property of parent */
 25:   (*v)->stash.donotstash   = win->stash.donotstash;
 26:   (*v)->stash.ignorenegidx = win->stash.ignorenegidx;

 28:   PetscCall(PetscObjectListDuplicate(((PetscObject)win)->olist, &((PetscObject)*v)->olist));
 29:   PetscCall(PetscFunctionListDuplicate(((PetscObject)win)->qlist, &((PetscObject)*v)->qlist));

 31:   (*v)->ops->duplicate = VecDuplicate_Shared;
 32:   (*v)->bstash.bs      = win->bstash.bs;
 33:   PetscFunctionReturn(PETSC_SUCCESS);
 34: }

 36: PETSC_EXTERN PetscErrorCode VecCreate_Shared(Vec vv)
 37: {
 38:   PetscScalar *array;

 40:   PetscFunctionBegin;
 41:   PetscCall(PetscSplitOwnership(PetscObjectComm((PetscObject)vv), &vv->map->n, &vv->map->N));
 42:   PetscCall(PetscSharedMalloc(PetscObjectComm((PetscObject)vv), vv->map->n * sizeof(PetscScalar), vv->map->N * sizeof(PetscScalar), (void **)&array));

 44:   PetscCall(VecCreate_MPI_Private(vv, PETSC_FALSE, 0, array));
 45:   vv->ops->duplicate = VecDuplicate_Shared;
 46:   PetscFunctionReturn(PETSC_SUCCESS);
 47: }

 49:   /* ----------------------------------------------------------------------------------------
 50:      Code to manage shared memory allocation using standard Unix shared memory
 51: */
 52: #include <petscsys.h>
 53:   #if defined(PETSC_HAVE_PWD_H)
 54:     #include <pwd.h>
 55:   #endif
 56:   #include <ctype.h>
 57:   #include <sys/stat.h>
 58:   #if defined(PETSC_HAVE_UNISTD_H)
 59:     #include <unistd.h>
 60:   #endif
 61:   #if defined(PETSC_HAVE_SYS_UTSNAME_H)
 62:     #include <sys/utsname.h>
 63:   #endif
 64:   #include <fcntl.h>
 65:   #include <time.h>
 66:   #if defined(PETSC_HAVE_SYS_SYSTEMINFO_H)
 67:     #include <sys/systeminfo.h>
 68:   #endif
 69:   #include <sys/shm.h>
 70:   #include <sys/mman.h>

 72: static PetscMPIInt Petsc_ShmComm_keyval = MPI_KEYVAL_INVALID;

 74: /*
 75:    Private routine to delete internal storage when a communicator is freed.
 76:   This is called by MPI, not by users.

 78:   The binding for the first argument changed from MPI 1.0 to 1.1; in 1.0
 79:   it was MPI_Comm *comm.
 80: */
 81: static PetscErrorCode Petsc_DeleteShared(MPI_Comm comm, PetscInt keyval, void *attr_val, void *extra_state)
 82: {
 83:   PetscFunctionBegin;
 84:   PetscCall(PetscFree(attr_val));
 85:   PetscFunctionReturn(MPI_SUCCESS);
 86: }

 88: /*

 90:     This routine is still incomplete and needs work.

 92:     For this to work on the Apple Mac OS X you will likely need to add something line the following to the file /etc/sysctl.conf
 93: cat /etc/sysctl.conf
 94: kern.sysv.shmmax=67108864
 95: kern.sysv.shmmin=1
 96: kern.sysv.shmmni=32
 97: kern.sysv.shmseg=512
 98: kern.sysv.shmall=1024

100:   This does not currently free the shared memory after the program runs. Use the Unix command ipcs to see the shared memory in use and
101: ipcrm to remove the shared memory in use.

103: */
104: PetscErrorCode PetscSharedMalloc(MPI_Comm comm, PetscInt llen, PetscInt len, void **result)
105: {
106:   PetscInt    shift;
107:   PetscMPIInt rank, flag;
108:   int        *arena, id, key = 0;
109:   char       *value;

111:   PetscFunctionBegin;
112:   *result = 0;

114:   PetscCallMPI(MPI_Scan(&llen, &shift, 1, MPI_INT, MPI_SUM, comm));
115:   shift -= llen;

117:   PetscCallMPI(MPI_Comm_rank(comm, &rank));
118:   if (rank == 0) {
119:     id = shmget(key, len, 0666 | IPC_CREAT);
120:     if (id == -1) {
121:       perror("Unable to malloc shared memory");
122:       SETERRQ(PETSC_COMM_SELF, PETSC_ERR_LIB, "Unable to malloc shared memory");
123:     }
124:   } else {
125:     id = shmget(key, len, 0666);
126:     if (id == -1) {
127:       perror("Unable to malloc shared memory");
128:       SETERRQ(PETSC_COMM_SELF, PETSC_ERR_LIB, "Unable to malloc shared memory");
129:     }
130:   }
131:   value = shmat(id, (void *)0, 0);
132:   if (value == (char *)-1) {
133:     perror("Unable to access shared memory allocated");
134:     SETERRQ(PETSC_COMM_SELF, PETSC_ERR_LIB, "Unable to access shared memory allocated");
135:   }
136:   *result = (void *)(value + shift);
137:   PetscFunctionReturn(PETSC_SUCCESS);
138: }

140: #else

142: PETSC_EXTERN PetscErrorCode VecCreate_Shared(Vec vv)
143: {
144:   PetscMPIInt size;

146:   PetscFunctionBegin;
147:   PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)vv), &size));
148:   PetscCheck(size <= 1, PETSC_COMM_SELF, PETSC_ERR_SUP_SYS, "No supported for shared memory vector objects on this machine");
149:   PetscCall(VecCreate_Seq(vv));
150:   PetscFunctionReturn(PETSC_SUCCESS);
151: }

153: #endif

155: /*@
156:   VecCreateShared - Creates a parallel vector that uses shared memory.

158:   Collective

160:   Input Parameters:
161: + comm - the MPI communicator to use
162: . n    - local vector length (or `PETSC_DECIDE` to have calculated if `N` is given)
163: - N    - global vector length (or `PETSC_DECIDE` to have calculated if `n` is given)

165:   Output Parameter:
166: . v - the vector

168:   Level: advanced

170:   Notes:
171:   Currently `VecCreateShared()` is available only on the SGI; otherwise,
172:   this routine is the same as `VecCreateMPI()`.

174:   Use `VecDuplicate()` or `VecDuplicateVecs()` to form additional vectors of the
175:   same type as an existing vector.

177: .seealso: [](ch_vectors), `Vec`, `VecType`, `VecCreateSeq()`, `VecCreate()`, `VecCreateMPI()`, `VecDuplicate()`, `VecDuplicateVecs()`,
178:           `VecCreateGhost()`, `VecCreateMPIWithArray()`, `VecCreateGhostWithArray()`
179: @*/
180: PetscErrorCode VecCreateShared(MPI_Comm comm, PetscInt n, PetscInt N, Vec *v)
181: {
182:   PetscFunctionBegin;
183:   PetscCall(VecCreate(comm, v));
184:   PetscCall(VecSetSizes(*v, n, N));
185:   PetscCall(VecSetType(*v, VECSHARED));
186:   PetscFunctionReturn(PETSC_SUCCESS);
187: }