Hi Jim, General comment: the word "process" in the MPI Standard is not well-defined. IMHO, it should always be short-hand for "MPI process" but it is often taken to mean "OS process". Adding a new implicit meaning, i.e. "endpoint", is not helpful. There is a one-to-many relationship between OS process and MPI process. There is a one-to-many relationship between MPI process and endpoint. The term "process" is used to refer to the child, the parent, or the grandparent in this hierarchy with the context (hopefully) determining which meaning is intended. I've re-read all of the new text looking for process/rank wording issues. There are some inconsistencies where "rank" in the parent communicator is still used. Page 244, lines 36-37 %%CURRENT associated with a single calling rank in parent_comm. %%SUGGESTION associated with a single calling process in parent_comm. Page 244, line 39 %%CURRENT at the corresponding rank in parent_comm. %%SUGGESTION at the corresponding process in parent_comm. Page 244, lines 39-40 %%CURRENT Ranks associated with a process in parent_comm are numbered contiguously in the output communicator, and %%PROBLEM "process in parent_comm" is intended to refer to "rank in parent_comm". Example: create an endpoints communicator, use split to re-order the ranks then create another endpoints communicator. The ranks associated with an OS process may not be contiguous - they may consist of several sub-groups (each of which is internally contiguous), one per local rank in parent_comm. %%SUGGESTION1 Ranks in new_comm_handles are numbered contiguously in the output communicator and %%SUGGESTION2 (preferred) Ranks in new_comm_handles are numbered contiguously and Page 244, lines 40-41 %%CURRENT and the starting rank is de fined by the order of the associated rank in the parent communicator. %%PROBLEM "associated rank" is intended to refer to "calling process" %%SUGGESTION and the starting rank is de fined by the order of the calling process in parent_comm. Other comments: %%PROBLEM The statements about cached information, valid values for my_num_ep, and the condition for the error code/class all apply to the inter-communicator case as well as the intra-communicator case. Should this be made clearer by moving that text out of the intra-communicator paragraph and after the inter-communicator paragraph? %%SUGGESTION If parent_comm is an intracommunicator ... sum of the values of my_num_ep on all calling processes. If parent_comm is an intercommunicator ... MPI_COMM_NULL is returned in all entries of new_comm_handles. <p>No cached information ... this function will return MPI_ERR_ENDPOINTS at all processes. Page 245 line 20 %%CURRENT Some operations, such as collective operations, cannot be used %%PROBLEM A single thread can perform a non-blocking collective even when there are multiple local endpoints. This would only require MPI_THREAD_SINGLE. %%SUGGESTION Some operations, such as blocking collective operations, cannot be used Cheers, Dan. On 01/07/2014 01:45, Jim Dinan wrote:
All,
Below are two options for the endpoints error text:
%% OLD: If the MPI implementation is not able to create a new communicator because of the \mpiarg{my\_num\_ep} argument given by any process, this function will return \error{MPI\_ERR\_ENDPOINTS}.
%% Option 2 (Suggested by Pavan): If a process provides a valid \mpiarg{my\_num\_ep} argument, but the MPI implementation is not able to create a new communicator because of the \mpiarg{my\_num\_ep} argument at this process, this function will return \error{MPI\_ERR\_ENDPOINTS} at all processes.
%% Option 1 (Smallest delta from old text): If the MPI implementation is not able to create a new communicator because a valid \mpiarg{my\_num\_ep} argument given by any process, this function will return \error{MPI\_ERR\_ENDPOINTS} at all processes.
Opinions or suggestions for improvement?
I have attached an updated review document (with option 2 above, but this is still open for discussion). Please review page 245, lines 7-15. I removed the use of "endpoint" and replaced it with "rank". I also replaced instances where we talk about "rank" in the parent communicator with "process". I think it's clearer now; interested to hear feedback.
Cheers, ~Jim.
On Mon, Jun 30, 2014 at 11:43 AM, Jim Dinan <[email protected]> wrote:
I can attend, but will be 10 minutes late. Attached is an updated copy of the endpoints proposal with feedback from the Chicago meeting. Let's review these changes, and we also have an item to discuss from that meeting with regard to how errors are returned from MPI_Comm_create_endpoints.
On Sun, Jun 29, 2014 at 2:40 PM, Balaji, Pavan <[email protected]> wrote:
All,
This is a reminder that we'll have our hybrid WG telecon tomorrow (06/30) at 11am central time.
I've made the promised corrections to ticket 411 and uploaded a new draft.
https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/411
We can discuss this tomorrow, together with the remaining tickets.
Thanks,
--- Pavan
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