log2_comm_size 837 ompi/mca/coll/base/coll_base_reduce_scatter_block.c int log2_comm_size = opal_cube_dim(comm_size); log2_comm_size 841 ompi/mca/coll/base/coll_base_reduce_scatter_block.c char *dst = psend + (ptrdiff_t)ompi_mirror_perm(i, log2_comm_size) * extent * rcount;