Date: 2021-03-03T22:25:54+00:00

Actual source code: shvec.c
petsc-3.14.5 2021-03-03
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      2: /*
      3:    This file contains routines for Parallel vector operations that use shared memory
      4:  */
      5: #include <../src/vec/vec/impls/mpi/pvecimpl.h>

      7: #if defined(PETSC_USE_SHARED_MEMORY)

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

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

     18:   /* first processor allocates entire array and sends it's address to the others */
     19:   PetscSharedMalloc(PetscObjectComm((PetscObject)win),win->map->n*sizeof(PetscScalar),win->map->N*sizeof(PetscScalar),(void**)&array);

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

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

     30:   PetscObjectListDuplicate(((PetscObject)win)->olist,&((PetscObject)*v)->olist);
     31:   PetscFunctionListDuplicate(((PetscObject)win)->qlist,&((PetscObject)*v)->qlist);

     33:   (*v)->ops->duplicate = VecDuplicate_Shared;
     34:   (*v)->bstash.bs      = win->bstash.bs;
     35:   return(0);
     36: }

     39: PETSC_EXTERN PetscErrorCode VecCreate_Shared(Vec vv)
     40: {
     42:   PetscScalar    *array;

     45:   PetscSplitOwnership(PetscObjectComm((PetscObject)vv),&vv->map->n,&vv->map->N);
     46:   PetscSharedMalloc(PetscObjectComm((PetscObject)vv),vv->map->n*sizeof(PetscScalar),vv->map->N*sizeof(PetscScalar),(void**)&array);

     48:   VecCreate_MPI_Private(vv,PETSC_FALSE,0,array);
     49:   vv->ops->duplicate = VecDuplicate_Shared;
     50:   return(0);
     51: }

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

     77: static PetscMPIInt Petsc_ShmComm_keyval = MPI_KEYVAL_INVALID;

     79: /*
     80:    Private routine to delete internal storage when a communicator is freed.
     81:   This is called by MPI, not by users.

     83:   The binding for the first argument changed from MPI 1.0 to 1.1; in 1.0
     84:   it was MPI_Comm *comm.
     85: */
     86: static PetscErrorCode Petsc_DeleteShared(MPI_Comm comm,PetscInt keyval,void *attr_val,void *extra_state)
     87: {

     91:   PetscFree(attr_val);
     92:   PetscFunctionReturn(MPI_SUCCESS);
     93: }

     95: /*

     97:     This routine is still incomplete and needs work.

     99:     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
    100: cat /etc/sysctl.conf
    101: kern.sysv.shmmax=67108864
    102: kern.sysv.shmmin=1
    103: kern.sysv.shmmni=32
    104: kern.sysv.shmseg=512
    105: kern.sysv.shmall=1024

    107:   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
    108: ipcrm to remove the shared memory in use.

    110: */
    111: PetscErrorCode PetscSharedMalloc(MPI_Comm comm,PetscInt llen,PetscInt len,void **result)
    112: {
    114:   PetscInt       shift;
    115:   PetscMPIInt    rank,flag;
    116:   int            *arena,id,key = 0;
    117:   char           *value;

    120:   *result = 0;

    122:   MPI_Scan(&llen,&shift,1,MPI_INT,MPI_SUM,comm);
    123:   shift -= llen;

    125:   MPI_Comm_rank(comm,&rank);
    126:   if (!rank) {
    127:     id = shmget(key,len, 0666 |IPC_CREAT);
    128:     if (id == -1) {
    129:       perror("Unable to malloc shared memory");
    130:       SETERRQ(PETSC_COMM_SELF,PETSC_ERR_LIB,"Unable to malloc shared memory");
    131:     }
    132:   } else {
    133:     id = shmget(key,len, 0666);
    134:     if (id == -1) {
    135:       perror("Unable to malloc shared memory");
    136:       SETERRQ(PETSC_COMM_SELF,PETSC_ERR_LIB,"Unable to malloc shared memory");
    137:     }
    138:   }
    139:   value = shmat(id,(void*)0,0);
    140:   if (value == (char*)-1) {
    141:     perror("Unable to access shared memory allocated");
    142:     SETERRQ(PETSC_COMM_SELF,PETSC_ERR_LIB,"Unable to access shared memory allocated");
    143:   }
    144:   *result = (void*) (value + shift);
    145:   return(0);
    146: }

    148: #else

    150: PETSC_EXTERN PetscErrorCode VecCreate_Shared(Vec vv)
    151: {
    153:   PetscMPIInt    size;

    156:   MPI_Comm_size(PetscObjectComm((PetscObject)vv),&size);
    157:   if (size > 1) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP_SYS,"No supported for shared memory vector objects on this machine");
    158:   VecCreate_Seq(vv);
    159:   return(0);
    160: }

    162: #endif

    164: /*@
    165:    VecCreateShared - Creates a parallel vector that uses shared memory.

    167:    Input Parameters:
    168: +  comm - the MPI communicator to use
    169: .  n - local vector length (or PETSC_DECIDE to have calculated if N is given)
    170: -  N - global vector length (or PETSC_DECIDE to have calculated if n is given)

    172:    Output Parameter:
    173: .  vv - the vector

    175:    Collective

    177:    Notes:
    178:    Currently VecCreateShared() is available only on the SGI; otherwise,
    179:    this routine is the same as VecCreateMPI().

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

    184:    Level: advanced

    186: .seealso: VecCreateSeq(), VecCreate(), VecCreateMPI(), VecDuplicate(), VecDuplicateVecs(),
    187:           VecCreateGhost(), VecCreateMPIWithArray(), VecCreateGhostWithArray()

    189: @*/
    190: PetscErrorCode  VecCreateShared(MPI_Comm comm,PetscInt n,PetscInt N,Vec *v)
    191: {

    195:   VecCreate(comm,v);
    196:   VecSetSizes(*v,n,N);
    197:   VecSetType(*v,VECSHARED);
    198:   return(0);
    199: }