On Tue, Aug 30, 2011 at 1:36 AM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
> On Mon, Aug 29, 2011 at 20:32, Tabrez Ali <stali at geology.wisc.edu> wrote: > >> If during Vecscatter (say from a global vector x to a local vector y) if >> 'is' and 'iy' are such that almost all values being scattered happen to be >> on the local proc then almost 0 or very little MPI calls would be made >> internally. Is this correct? >> > > Very few values would be sent anywhere. The number of MPI calls depends on > the number of processes that need to receive values and the scatter method > (methods descriptions: > http://www.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-dev/docs/manualpages/Vec/VecScatterCreate.html > ). > Also, you can make an event around these calls and get information on the number of messages and the average size. Matt -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20110830/0b0ba95d/attachment.htm>
