ad_write_coll.c

MPICH是MPI的重要研究,提供了一系列的接口函数,为并行计算的实现提供了编程环境.

    recv_size = (int *) ADIOI_Malloc(nprocs*sizeof(int));
    /* total size of data to be recd. from each proc. in an iteration.*/

    sent_to_proc = (int *) ADIOI_Calloc(nprocs, sizeof(int));
    /* amount of data sent to each proc so far. Used in
       ADIOI_Fill_send_buffer. initialized to 0 here. */

    send_buf_idx = (int *) ADIOI_Malloc(nprocs*sizeof(int));
    curr_to_proc = (int *) ADIOI_Malloc(nprocs*sizeof(int));
    done_to_proc = (int *) ADIOI_Malloc(nprocs*sizeof(int));
    /* Above three are used in ADIOI_Fill_send_buffer*/

    start_pos = (int *) ADIOI_Malloc(nprocs*sizeof(int));
    /* used to store the starting value of curr_offlen_ptr[i] in 
       this iteration */

    ADIOI_Datatype_iscontig(datatype, &buftype_is_contig);
    if (!buftype_is_contig) {
	ADIOI_Flatten_datatype(datatype);
	flat_buf = ADIOI_Flatlist;
        while (flat_buf->type != datatype) flat_buf = flat_buf->next;
    }
    MPI_Type_extent(datatype, &buftype_extent);


/* I need to check if there are any outstanding nonblocking writes to
   the file, which could potentially interfere with the writes taking
   place in this collective write call. Since this is not likely to be
   common, let me do the simplest thing possible here: Each process
   completes all pending nonblocking operations before completing. */

    ADIOI_Complete_async(error_code);
    if (*error_code != MPI_SUCCESS) return;
    MPI_Barrier(fd->comm);

    done = 0;
    off = st_loc;

#ifdef PROFILE
	MPE_Log_event(14, 0, "end computation");
#endif

    for (m=0; m < ntimes; m++) {
       /* go through all others_req and check which will be satisfied
          by the current write */

       /* Note that MPI guarantees that displacements in filetypes are in 
          monotonically nondecreasing order and that, for writes, the
	  filetypes cannot specify overlapping regions in the file. This
	  simplifies implementation a bit compared to reads. */

          /* off = start offset in the file for the data to be written in 
                   this iteration 
             size = size of data written (bytes) corresponding to off
             req_off = off in file for a particular contiguous request 
                       minus what was satisfied in previous iteration
             req_size = size corresponding to req_off */

	/* first calculate what should be communicated */

#ifdef PROFILE
	MPE_Log_event(13, 0, "start computation");
#endif
	for (i=0; i < nprocs; i++) count[i] = recv_size[i] = 0;

	size = (int) (ADIOI_MIN(coll_bufsize, end_loc-st_loc+1-done)); 

	for (i=0; i < nprocs; i++) {
	    if (others_req[i].count) {
		start_pos[i] = curr_offlen_ptr[i];
		for (j=curr_offlen_ptr[i]; j<others_req[i].count; j++) {
		    if (partial_recv[i]) {
			/* this request may have been partially
			   satisfied in the previous iteration. */
			req_off = others_req[i].offsets[j] +
			    partial_recv[i]; 
                        req_len = others_req[i].lens[j] -
			    partial_recv[i];
			partial_recv[i] = 0;
			/* modify the off-len pair to reflect this change */
			others_req[i].offsets[j] = req_off;
			others_req[i].lens[j] = req_len;
		    }
		    else {
			req_off = others_req[i].offsets[j];
                        req_len = others_req[i].lens[j];
		    }
		    if (req_off < off + size) {
			count[i]++;
			MPI_Address(write_buf+req_off-off, 
                               &(others_req[i].mem_ptrs[j]));
			recv_size[i] += (int)(ADIOI_MIN(off + (ADIO_Offset)size - 
						  req_off, req_len));

			if (off+size-req_off < req_len) {
			    partial_recv[i] = (int) (off + size - req_off);
			    if ((j+1 < others_req[i].count) && 
                                 (others_req[i].offsets[j+1] < 
                                     off+size)) { 
				FPRINTF(stderr, "Error: the filetype specifies an overlapping write\n");
				MPI_Abort(MPI_COMM_WORLD, 1);
			    }
			    break;
			}
		    }
		    else break;
		}
		curr_offlen_ptr[i] = j;
	    }
	}
	
#ifdef PROFILE
	MPE_Log_event(14, 0, "end computation");
	MPE_Log_event(7, 0, "start communication");
#endif
	ADIOI_W_Exchange_data(fd, buf, write_buf, flat_buf, offset_list, 
                            len_list, send_size, recv_size, off, size, count, 
                            start_pos, partial_recv, 
                            sent_to_proc, nprocs, myrank, 
			    buftype_is_contig, contig_access_count,
			    min_st_offset, fd_size, fd_start, fd_end,
			    others_req, send_buf_idx, curr_to_proc,
                            done_to_proc, &hole, m, buftype_extent, buf_idx,
			    error_code); 
        if (*error_code != MPI_SUCCESS) return;
#ifdef PROFILE
	MPE_Log_event(8, 0, "end communication");
#endif

	flag = 0;
	for (i=0; i<nprocs; i++)
	    if (count[i]) flag = 1;

	if (flag) {
	    ADIO_WriteContig(fd, write_buf, size, MPI_BYTE, ADIO_EXPLICIT_OFFSET, 
                        off, &status, error_code);
	    if (*error_code != MPI_SUCCESS) return;
	}

	off += size;
	done += size;
    }

    for (i=0; i<nprocs; i++) count[i] = recv_size[i] = 0;
#ifdef PROFILE
	MPE_Log_event(7, 0, "start communication");
#endif
    for (m=ntimes; m<max_ntimes; m++) 
/* nothing to recv, but check for send. */
	ADIOI_W_Exchange_data(fd, buf, write_buf, flat_buf, offset_list, 
                            len_list, send_size, recv_size, off, size, count, 
                            start_pos, partial_recv, 
                            sent_to_proc, nprocs, myrank, 
			    buftype_is_contig, contig_access_count,
			    min_st_offset, fd_size, fd_start, fd_end,
			    others_req, send_buf_idx, 
                            curr_to_proc, done_to_proc, &hole, m, 
                            buftype_extent, buf_idx, error_code); 
        if (*error_code != MPI_SUCCESS) return;
#ifdef PROFILE
	MPE_Log_event(8, 0, "end communication");
#endif

    if (ntimes) ADIOI_Free(write_buf);
    ADIOI_Free(curr_offlen_ptr);
    ADIOI_Free(count);
    ADIOI_Free(partial_recv);
    ADIOI_Free(send_size);
    ADIOI_Free(recv_size);
    ADIOI_Free(sent_to_proc);
    ADIOI_Free(start_pos);
    ADIOI_Free(send_buf_idx);
    ADIOI_Free(curr_to_proc);
    ADIOI_Free(done_to_proc);
}



static void ADIOI_W_Exchange_data(ADIO_File fd, void *buf, char *write_buf,
                         ADIOI_Flatlist_node *flat_buf, ADIO_Offset 
                         *offset_list, int *len_list, int *send_size, 
                         int *recv_size, ADIO_Offset off, int size,
			 int *count, int *start_pos, int *partial_recv,
			 int *sent_to_proc, int nprocs, 
			 int myrank, int
			 buftype_is_contig, int contig_access_count,
			 ADIO_Offset min_st_offset, ADIO_Offset fd_size,
			 ADIO_Offset *fd_start, ADIO_Offset *fd_end, 
			 ADIOI_Access *others_req, 
			 int *send_buf_idx, int *curr_to_proc,
			 int *done_to_proc, int *hole, int iter, 
                         MPI_Aint buftype_extent, int *buf_idx,
                         int *error_code)
{
    int i, j, k, *tmp_len, nprocs_recv, nprocs_send, err;
    char **send_buf = NULL; 
    MPI_Request *requests;
    MPI_Datatype *recv_types;
    MPI_Status *statuses, status;
    int *srt_len, sum;
    ADIO_Offset *srt_off;
#ifndef PRINT_ERR_MSG
    static char myname[] = "ADIOI_W_EXCHANGE_DATA";
#endif

/* exchange recv_size info so that each process knows how much to
   send to whom. */

    MPI_Alltoall(recv_size, 1, MPI_INT, send_size, 1, MPI_INT, fd->comm);

    /* create derived datatypes for recv */

    nprocs_recv = 0;
    for (i=0; i<nprocs; i++) if (recv_size[i]) nprocs_recv++;

    recv_types = (MPI_Datatype *)
	ADIOI_Malloc((nprocs_recv+1)*sizeof(MPI_Datatype)); 
/* +1 to avoid a 0-size malloc */

    tmp_len = (int *) ADIOI_Malloc(nprocs*sizeof(int));
    j = 0;
    for (i=0; i<nprocs; i++) {
	if (recv_size[i]) {
/* take care if the last off-len pair is a partial recv */
	    if (partial_recv[i]) {
		k = start_pos[i] + count[i] - 1;
		tmp_len[i] = others_req[i].lens[k];
		others_req[i].lens[k] = partial_recv[i];
	    }
	    MPI_Type_hindexed(count[i], 
                 &(others_req[i].lens[start_pos[i]]),
	             &(others_req[i].mem_ptrs[start_pos[i]]), 
			 MPI_BYTE, recv_types+j);
	    /* absolute displacements; use MPI_BOTTOM in recv */
	    MPI_Type_commit(recv_types+j);
	    j++;
	}
    }

    /* To avoid a read-modify-write, check if there are holes in the 
       data to be written. For this, merge the (sorted) offset lists
       others_req using a heap-merge. */

    sum = 0;
    for (i=0; i<nprocs; i++) sum += count[i];
    srt_off = (ADIO_Offset *) ADIOI_Malloc((sum+1)*sizeof(ADIO_Offset));
    srt_len = (int *) ADIOI_Malloc((sum+1)*sizeof(int));
    /* +1 to avoid a 0-size malloc */

    ADIOI_Heap_merge(others_req, count, srt_off, srt_len, start_pos,
                     nprocs, nprocs_recv, sum);

/* for partial recvs, restore original lengths */
    for (i=0; i<nprocs; i++) 
        if (partial_recv[i]) {
            k = start_pos[i] + count[i] - 1;
            others_req[i].lens[k] = tmp_len[i];
        }
    ADIOI_Free(tmp_len);

/* check if there are any holes */
    *hole = 0;
    for (i=0; i<sum-1; i++)
	if (srt_off[i]+srt_len[i] < srt_off[i+1]) {
	    *hole = 1;
	    break;
	}

    ADIOI_Free(srt_off);
    ADIOI_Free(srt_len);

    if (nprocs_recv) {
	if (*hole) {
	    ADIO_ReadContig(fd, write_buf, size, MPI_BYTE, 
                         ADIO_EXPLICIT_OFFSET, off, &status, &err);
	    if (err != MPI_SUCCESS) {
#ifdef PRINT_ERR_MSG
		FPRINTF(stderr, "ADIOI_GEN_WriteStridedColl: ROMIO tries to optimize this access by doing a read-modify-write, but is unable to read the file. Please give the file read permission and open it with MPI_MODE_RDWR.\n");
		MPI_Abort(MPI_COMM_WORLD, 1);
#else
		*error_code = MPIR_Err_setmsg(MPI_ERR_IO, MPIR_READ_PERM,
			      myname, (char *) 0, (char *) 0);
		ADIOI_Error(fd, *error_code, myname);
                return;  
#endif
	    } 
	}
    }

    nprocs_send = 0;
    for (i=0; i < nprocs; i++) if (send_size[i]) nprocs_send++;

    requests = (MPI_Request *) 	
	ADIOI_Malloc((nprocs_send+nprocs_recv+1)*sizeof(MPI_Request)); 
/* +1 to avoid a 0-size malloc */

/* post receives */
    j = 0;
    for (i=0; i<nprocs; i++) {
	if (recv_size[i]) {
	    MPI_Irecv(MPI_BOTTOM, 1, recv_types[j], i, myrank+i+100*iter,
		      fd->comm, requests+j);
	    j++;
	}
    }

/* post sends. if buftype_is_contig, data can be directly sent from
   user buf at location given by buf_idx. else use send_buf. */

    if (buftype_is_contig) {
	j = 0;
	for (i=0; i < nprocs; i++) 
	    if (send_size[i]) {
		MPI_Isend(((char *) buf) + buf_idx[i], send_size[i], 
  		            MPI_BYTE, i,  myrank+i+100*iter, fd->comm, 
                                  requests+nprocs_recv+j);