If the application "ensures" that there are no messages in-flight, then I agree with you. I was thinking of applications that use asyncronous MPI communication in a multi-threaded env, potentially leading to unmatched messages..... -Kannan- ________________________________ From: [email protected] [mailto:[email protected]] On Behalf Of Greg Bronevetsky Sent: Thursday, October 23, 2008 2:59 PM To: MPI 3.0 Fault Tolerance and Dynamic Process Control working Group; MPI 3.0 Fault Tolerance and Dynamic Process Control working Group Subject: Re: [Mpi3-ft] Summary of today's meeting Application-directed C/R will still require some quiescence hooks from the MPI layer (ex: asyncronous progression by the MPI layer). There was some discussion on this. What kind of quiscence are you thinking of? It seems to me that applications will simply need to ensure that either no messages are in-flight at the time of the checkpoint or that all such messages have been logged appropriately by the application. Greg Bronevetsky Post-Doctoral Researcher 1028 Building 451 Lawrence Livermore National Lab (925) 424-5756 [email protected]