ad_read_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.

	    if (*error_code != MPI_SUCCESS) return;
	}
	
	for_curr_iter = for_next_iter;
	
#ifdef PROFILE
        MPE_Log_event(7, 0, "start communication");
#endif
	ADIOI_R_Exchange_data(fd, buf, flat_buf, offset_list, len_list,
			    send_size, recv_size, count, 
       			    start_pos, partial_send, recd_from_proc, nprocs,
			    myrank, 
			    buftype_is_contig, contig_access_count,
			    min_st_offset, fd_size, fd_start, fd_end,
			    others_req, 
                            m, buftype_extent, buf_idx); 

#ifdef PROFILE
        MPE_Log_event(8, 0, "end communication");
#endif

	if (for_next_iter) {
	    tmp_buf = (char *) ADIOI_Malloc(for_next_iter);
	    memcpy(tmp_buf, read_buf+real_size-for_next_iter, for_next_iter);
	    ADIOI_Free(read_buf);
	    read_buf = (char *) ADIOI_Malloc(for_next_iter+coll_bufsize);
	    memcpy(read_buf, tmp_buf, for_next_iter);
	    ADIOI_Free(tmp_buf);
	}

	off += size;
	done += size;
    }

    for (i=0; i<nprocs; i++) count[i] = send_size[i] = 0;
#ifdef PROFILE
        MPE_Log_event(7, 0, "start communication");
#endif
    for (m=ntimes; m<max_ntimes; m++) 
/* nothing to send, but check for recv. */
	ADIOI_R_Exchange_data(fd, buf, flat_buf, offset_list, len_list,
			    send_size, recv_size, count, 
			    start_pos, partial_send, recd_from_proc, nprocs,
			    myrank, 
			    buftype_is_contig, contig_access_count,
			    min_st_offset, fd_size, fd_start, fd_end,
			    others_req, m,
                            buftype_extent, buf_idx); 
#ifdef PROFILE
        MPE_Log_event(8, 0, "end communication");
#endif

    if (ntimes) ADIOI_Free(read_buf);
    ADIOI_Free(curr_offlen_ptr);
    ADIOI_Free(count);
    ADIOI_Free(partial_send);
    ADIOI_Free(send_size);
    ADIOI_Free(recv_size);
    ADIOI_Free(recd_from_proc);
    ADIOI_Free(start_pos);
}

static void ADIOI_R_Exchange_data(ADIO_File fd, void *buf, ADIOI_Flatlist_node
			 *flat_buf, ADIO_Offset *offset_list, int
                         *len_list, int *send_size, int *recv_size,
			 int *count, int *start_pos, int *partial_send, 
			 int *recd_from_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 iter, MPI_Aint buftype_extent, int *buf_idx)
{
    int i, j, k=0, tmp=0, nprocs_recv, nprocs_send;
    char **recv_buf = NULL; 
    MPI_Request *requests;
    MPI_Datatype send_type;
    MPI_Status *statuses;

/* exchange send_size info so that each process knows how much to
   receive from whom and how much memory to allocate. */

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

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

    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 recvs. if buftype_is_contig, data can be directly recd. into
   user buf at location given by buf_idx. else use recv_buf. */

    if (buftype_is_contig) {
	j = 0;
	for (i=0; i < nprocs; i++) 
	    if (recv_size[i]) {
		MPI_Irecv(((char *) buf) + buf_idx[i], recv_size[i], 
		  MPI_BYTE, i, myrank+i+100*iter, fd->comm, requests+j);
		j++;
		buf_idx[i] += recv_size[i];
	    }
    }
    else {
/* allocate memory for recv_buf and post receives */
	recv_buf = (char **) ADIOI_Malloc(nprocs * sizeof(char*));
	for (i=0; i < nprocs; i++) 
	    if (recv_size[i]) recv_buf[i] = 
                                  (char *) ADIOI_Malloc(recv_size[i]);

	    j = 0;
	    for (i=0; i < nprocs; i++) 
		if (recv_size[i]) {
		    MPI_Irecv(recv_buf[i], recv_size[i], MPI_BYTE, i, 
			      myrank+i+100*iter, fd->comm, requests+j);
		    j++;
		    /* FPRINTF(stderr, "node %d, recv_size %d, tag %d \n", 
		       myrank, recv_size[i], myrank+i+100*iter); */
		}
    }

/* create derived datatypes and send data */

    j = 0;
    for (i=0; i<nprocs; i++) {
	if (send_size[i]) {
/* take care if the last off-len pair is a partial send */
	    if (partial_send[i]) {
		k = start_pos[i] + count[i] - 1;
		tmp = others_req[i].lens[k];
		others_req[i].lens[k] = partial_send[i];
	    }
	    MPI_Type_hindexed(count[i], 
                 &(others_req[i].lens[start_pos[i]]),
	            &(others_req[i].mem_ptrs[start_pos[i]]), 
			 MPI_BYTE, &send_type);
	    /* absolute displacement; use MPI_BOTTOM in send */
	    MPI_Type_commit(&send_type);
	    MPI_Isend(MPI_BOTTOM, 1, send_type, i, myrank+i+100*iter,
		      fd->comm, requests+nprocs_recv+j);
	    MPI_Type_free(&send_type);
	    if (partial_send[i]) others_req[i].lens[k] = tmp;
	    j++;
	}
    }

    statuses = (MPI_Status *) ADIOI_Malloc((nprocs_send+nprocs_recv+1) * \
                                     sizeof(MPI_Status)); 
     /* +1 to avoid a 0-size malloc */

    /* wait on the receives */
    if (nprocs_recv) {
#ifdef NEEDS_MPI_TEST
	j = 0;
	while (!j) MPI_Testall(nprocs_recv, requests, &j, statuses);
#else
	MPI_Waitall(nprocs_recv, requests, statuses);
#endif

	/* if noncontiguous, to the copies from the recv buffers */
	if (!buftype_is_contig) 
	    ADIOI_Fill_user_buffer(fd, buf, flat_buf, recv_buf,
				   offset_list, len_list, recv_size, 
				   requests, statuses, recd_from_proc, 
				   nprocs, contig_access_count,
				   min_st_offset, fd_size, fd_start, fd_end,
				   buftype_extent);
    }

    /* wait on the sends*/
    MPI_Waitall(nprocs_send, requests+nprocs_recv, statuses+nprocs_recv);

    ADIOI_Free(statuses);
    ADIOI_Free(requests);

    if (!buftype_is_contig) {
	for (i=0; i < nprocs; i++) 
	    if (recv_size[i]) ADIOI_Free(recv_buf[i]);
	ADIOI_Free(recv_buf);
    }
}


#define ADIOI_BUF_INCR \
{ \
    while (buf_incr) { \
	size_in_buf = ADIOI_MIN(buf_incr, flat_buf_sz); \
	user_buf_idx += size_in_buf; \
	flat_buf_sz -= size_in_buf; \
	if (!flat_buf_sz) { \
            if (flat_buf_idx < (flat_buf->count - 1)) flat_buf_idx++; \
            else { \
                flat_buf_idx = 0; \
                n_buftypes++; \
            } \
            user_buf_idx = flat_buf->indices[flat_buf_idx] + \
                              n_buftypes*buftype_extent; \
	    flat_buf_sz = flat_buf->blocklens[flat_buf_idx]; \
	} \
	buf_incr -= size_in_buf; \
    } \
}


#define ADIOI_BUF_COPY \
{ \
    while (size) { \
	size_in_buf = ADIOI_MIN(size, flat_buf_sz); \
	memcpy(((char *) buf) + user_buf_idx, \
	       &(recv_buf[p][recv_buf_idx[p]]), size_in_buf); \
	recv_buf_idx[p] += size_in_buf; \
	user_buf_idx += size_in_buf; \
	flat_buf_sz -= size_in_buf; \
	if (!flat_buf_sz) { \
            if (flat_buf_idx < (flat_buf->count - 1)) flat_buf_idx++; \
            else { \
                flat_buf_idx = 0; \
                n_buftypes++; \
            } \
            user_buf_idx = flat_buf->indices[flat_buf_idx] + \
                              n_buftypes*buftype_extent; \
	    flat_buf_sz = flat_buf->blocklens[flat_buf_idx]; \
	} \
	size -= size_in_buf; \
	buf_incr -= size_in_buf; \
    } \
    ADIOI_BUF_INCR \
}


static void ADIOI_Fill_user_buffer(ADIO_File fd, void *buf, ADIOI_Flatlist_node
				   *flat_buf, char **recv_buf, ADIO_Offset 
				   *offset_list, int *len_list, 
				   int *recv_size, 
				   MPI_Request *requests, MPI_Status *statuses,
				   int *recd_from_proc, int nprocs,
				   int contig_access_count, 
				   ADIO_Offset min_st_offset, 
				   ADIO_Offset fd_size, ADIO_Offset *fd_start, 
				   ADIO_Offset *fd_end,
				   MPI_Aint buftype_extent)
{
/* this function is only called if buftype is not contig */

    int i, p, flat_buf_idx, size, buf_incr;
    int flat_buf_sz, size_in_buf, n_buftypes;
    ADIO_Offset off, len, rem_len, user_buf_idx;

    int *curr_from_proc, *done_from_proc, *recv_buf_idx;

/*  curr_from_proc[p] = amount of data recd from proc. p that has already
                        been accounted for so far
    done_from_proc[p] = amount of data already recd from proc. p and 
                        filled into user buffer in previous iterations
    user_buf_idx = current location in user buffer 
    recv_buf_idx[p] = current location in recv_buf of proc. p  */
    curr_from_proc = (int *) ADIOI_Malloc(nprocs * sizeof(int));
    done_from_proc = (int *) ADIOI_Malloc(nprocs * sizeof(int));
    recv_buf_idx   = (int *) ADIOI_Malloc(nprocs * sizeof(int));

    for (i=0; i < nprocs; i++) {
	recv_buf_idx[i] = curr_from_proc[i] = 0;
	done_from_proc[i] = recd_from_proc[i];
    }

    user_buf_idx = flat_buf->indices[0];
    flat_buf_idx = 0;
    n_buftypes = 0;
    flat_buf_sz = flat_buf->blocklens[0];

    /* flat_buf_idx = current index into flattened buftype
       flat_buf_sz = size of current contiguous component in 
                flattened buf */

    for (i=0; i<contig_access_count; i++) { 
	off     = offset_list[i];
	rem_len = (ADIO_Offset) len_list[i];

	/* this request may span the file domains of more than one process */
	while (rem_len != 0) {
	    len = rem_len;
	    /* NOTE: len value is modified by ADIOI_Calc_aggregator() to be no
	     * longer than the single region that processor "p" is responsible
	     * for.
	     */
	    p = ADIOI_Calc_aggregator(fd,
				      off,
				      min_st_offset,
				      &len,
				      fd_size,
				      fd_start,
				      fd_end);

	    if (recv_buf_idx[p] < recv_size[p]) {
		if (curr_from_proc[p]+len > done_from_proc[p]) {
		    if (done_from_proc[p] > curr_from_proc[p]) {
			size = (int)ADIOI_MIN(curr_from_proc[p] + len - 
			      done_from_proc[p], recv_size[p]-recv_buf_idx[p]);
			buf_incr = done_from_proc[p] - curr_from_proc[p];
			ADIOI_BUF_INCR
			buf_incr = (int)(curr_from_proc[p]+len-done_from_proc[p]);
			curr_from_proc[p] = done_from_proc[p] + size;
			ADIOI_BUF_COPY
		    }
		    else {
			size = (int)ADIOI_MIN(len,recv_size[p]-recv_buf_idx[p]);
			buf_incr = (int)len;
			curr_from_proc[p] += size;
			ADIOI_BUF_COPY
		    }
		}
		else {
		    curr_from_proc[p] += (int)len;
		    buf_incr = (int)len;
		    ADIOI_BUF_INCR
		}
	    }
	    else {
		buf_incr = (int)len;
		ADIOI_BUF_INCR
	    }
	    off     += len;
	    rem_len -= len;
	}
    }
    for (i=0; i < nprocs; i++) 
	if (recv_size[i]) recd_from_proc[i] = curr_from_proc[i];

    ADIOI_Free(curr_from_proc);
    ADIOI_Free(done_from_proc);
    ADIOI_Free(recv_buf_idx);
}