"synchronizing operation" not defined in Chapter 2

[cblaas]

Problem

We define what "synchronizing" means for procedures (see at the end of 2.4.2 MPI Procedures) but not what it means for operations (2.4.1 MPI Operations).

This came up during the review of MPI 4.1 RC in September 2023 when we decided to write "synchronizing operation" in several occasions (e.g., in Chapter 7).

Proposal

Define "synchronizing operation" in Chapter 2.

Changes to the Text

Define "synchronizing operation" in Chapter 2.

Impact on Implementations

none

Impact on Users

Improved quality of the document.

References and Pull Requests

[Wee-Free-Scot]

The starting-point for text about "synchronizing operation" is the S2 definition in section A.2:

– S1 = blocking synchronization, i.e., no process shall return from this procedure until all
processes on the associated process group called this procedure
– W1 = the implementation is permitted to do S1 but not required to do S1
– S2 = start-complete-synchronization, i.e., no process shall complete the associated operation until all processes on the associated process group have called the associated
starting procedure
– W2 = the implementation is permitted to do S2 but not required to do S2