diff options
Diffstat (limited to 'src/H5Fmpio.c')
| -rw-r--r-- | src/H5Fmpio.c | 81 |
1 files changed, 80 insertions, 1 deletions
diff --git a/src/H5Fmpio.c b/src/H5Fmpio.c index 50e7ddc..7214d6b 100644 --- a/src/H5Fmpio.c +++ b/src/H5Fmpio.c @@ -69,6 +69,10 @@ static hbool_t interface_initialize_g = FALSE; /* rky??? */ #define INTERFACE_INIT NULL +/* Global var to allow elimination of redundant metadata writes + * to be controlled by the value of an environment variable. */ +hbool_t H5_mpi_1_metawrite_g = FALSE; + #define H5F_MPIO_DEV 0xfffe /*pseudo dev for MPI-IO until we fix things */ /* Make sure this differs from H5F_CORE_DEV */ @@ -285,6 +289,7 @@ H5F_mpio_access(const char *name, const H5F_access_t *access_parms, int mode, * rky, 11 Jun 1998 * Added H5F_mpio_Debug debug flags controlled by MPI_Info. * + * rky 980828 Init flag controlling redundant metadata writes to disk. *------------------------------------------------------------------------- */ static H5F_low_t * @@ -351,6 +356,7 @@ H5F_mpio_open(const char *name, const H5F_access_t *access_parms, uintn flags, "memory allocation failed"); } lf->u.mpio.f = fh; + H5F_mpio_tas_allsame( lf, FALSE ); /* initialize */ H5F_addr_reset(&(lf->eof)); mpierr = MPI_File_get_size( fh, &size ); if (MPI_SUCCESS != mpierr) { @@ -627,6 +633,45 @@ H5F_mpio_read(H5F_low_t *lf, H5F_access_t *access_parms, } /* H5F_mpio_read */ /*------------------------------------------------------------------------- + * Function: H5F_mpio_tas_allsame + * + * Purpose: Test and set the allsame parameter. + * + * Errors: + * + * Return: Success: the old value of the allsame flag + * + * Failure: assert fails if access_parms is NULL. + * + * Programmer: rky 980828 + * + * Modifications: + * + *------------------------------------------------------------------------- + */ +hbool_t +H5F_mpio_tas_allsame(H5F_low_t *lf, hbool_t newval ) +{ + hbool_t oldval; + + FUNC_ENTER(H5F_mpio_tas_allsame, FALSE); +#ifdef H5Fmpio_DEBUG + if (H5F_mpio_Debug[(int)'t']) + fprintf(stdout, "Entering H5F_mpio_tas_allsame, newval=%d\n", newval ); +#endif + + assert(lf); + oldval = lf->u.mpio.allsame; + lf->u.mpio.allsame = newval; + +#ifdef H5Fmpio_DEBUG + if (H5F_mpio_Debug[(int)'t']) + fprintf(stdout, "Leaving H5F_mpio_tas_allsame, oldval=%d\n", oldval ); +#endif + FUNC_LEAVE(oldval); +} + +/*------------------------------------------------------------------------- * Function: H5F_mpio_write * * Purpose: Depending on a field in access params, either: @@ -637,6 +682,19 @@ H5F_mpio_read(H5F_low_t *lf, H5F_access_t *access_parms, * This can allow MPI to coalesce requests from * different processes (collective or independent). * + * rky 980828 + * If the allsame flag is set, we assume that all the procs + * in the relevant MPI communicator will write identical data + * at identical offsets in the file, so only proc 0 will write, + * and all other procs will wait for p0 to finish. + * This is useful for writing metadata, for example. + * Note that we don't _check_ that the data is identical. + * ALso, the mechanism we use to eliminate the redundant writes + * is by requiring a call to H5F_mpio_tas_allsame before the write, + * which is rather klugey. + * Would it be better to pass a parameter to low-level writes + * like H5F_block_write and H5F_low_write, instead? Or...??? + * * Errors: * IO WRITEERROR MPI_File_write_at failed. * @@ -666,6 +724,9 @@ H5F_mpio_read(H5F_low_t *lf, H5F_access_t *access_parms, * The guts of H5F_mpio_read and H5F_mpio_write * should be replaced by a single dual-purpose routine. * + * rky, 980828 + * Added allsame parameter to make all but proc 0 skip the actual write. + * *------------------------------------------------------------------------- */ static herr_t @@ -676,9 +737,10 @@ H5F_mpio_write(H5F_low_t *lf, H5F_access_t *access_parms, MPI_Offset mpi_off, mpi_disp; MPI_Status mpi_stat; MPI_Datatype buf_type, file_type; - int mpierr, msglen, size_i, bytes_written; + int mpierr, msglen, size_i, bytes_written, mpi_rank; int use_types_this_time, used_types_last_time; char mpierrmsg[MPI_MAX_ERROR_STRING]; + hbool_t allsame; FUNC_ENTER(H5F_mpio_write, FAIL); #ifdef H5Fmpio_DEBUG @@ -707,6 +769,22 @@ H5F_mpio_write(H5F_low_t *lf, H5F_access_t *access_parms, mpi_off, size_i ); #endif + /* Only p0 will do the actual write if all procs in comm write same data */ + allsame = H5F_mpio_tas_allsame( lf, FALSE ); + if (allsame && H5_mpi_1_metawrite_g) { + mpierr = MPI_Comm_rank( access_parms->u.mpio.comm, &mpi_rank ); + if (mpierr != MPI_SUCCESS) + HRETURN_ERROR(H5E_IO, H5E_MPI, FAIL, "MPI_Comm_rank failed" ); + if (mpi_rank != 0) { +#ifdef H5Fmpio_DEBUG + if (H5F_mpio_Debug[(int)'w']) { + fprintf(stdout, " in H5F_mpio_write (write omitted)\n" ); + } +#endif + goto done; /* skip the actual write */ + } + } + /* Set up for a fancy xfer using complex types, or single byte block. * We wouldn't need to rely on the use_types field * if MPI semantics allowed us to test that btype=ftype=MPI_BYTE @@ -797,6 +875,7 @@ H5F_mpio_write(H5F_low_t *lf, H5F_access_t *access_parms, "MPI_Get_count returned invalid count" ); } + done: #ifdef H5Fmpio_DEBUG if (H5F_mpio_Debug[(int)'t']) fprintf(stdout, "Leaving H5F_mpio_write\n" ); |