Re: [Starpu-devel] Question sur starpu_data_set_rank

[Samuel Thibault <samuel.thibault@ens-lyon.org>]

Cyril Bordage, le Sun 15 Jul 2012 21:45:37 +0200, a écrit :
> Quand je prends l'exemple du stencil d'"info starpu", je ne comprends pas
> comment sans synchronisation, il est possible pour plusieurs processus de
> savoir qu'ils parlent du même handle.

Actually, calling starpu_data_set_tag is *required* for things to work
properly, because the actual mpi_send/recv call order is not necessarily
the same as the task submission order, and thus the send/recv pairing is
not necessarily correct. For a given handle, however, these are always
in submission order (since that's the sequential consistency order).
Thus using one tag per handle.

Samuel