Dear Josh, I hope to see this new API soon. Anyway, I will try these critical section functions in BLCR. Thank you for the support.
Best Regards, Nguyen Toan On Sat, Jul 17, 2010 at 6:34 AM, Josh Hursey <jjhur...@open-mpi.org> wrote: > > On Jun 14, 2010, at 5:26 AM, Nguyen Toan wrote: > > > Hi all, > > I have a MPI program as follows: > > ------------------- > > int main(){ > > MPI_Init(); > > ...... > > for (i=0; i<10000; i++) { > > my_atomic_func(); > > } > > ... > > MPI_Finalize(); > > return 0; > > } > > -------------------- > > > > The runtime of this program mainly involves in running the loop and > my_atomic_func() takes a little bit long. > > Here I want my_atomic_func() to be operated atomically, but the timing of > checkpointing (by running ompi-checkpoint command) may be in the middle of > my_atomic_func() operation and hence ompi-restart may fail to restart > correctly. > > > > So my question is: > > + At the checkpoint time (executing ompi-checkpoint), is there a way to > let OpenMPI wait until my_atomic_func() finishes its operation? > > We do not currently have an external function to declare a critical section > during which a checkpoint should not be taken. I filed a ticket to make one > available. The link is below if you would like to follow its progress: > https://svn.open-mpi.org/trac/ompi/ticket/2487 > > I have an MPI Extension interface for C/R that I will be bringing into the > trunk in the next few weeks. I should be able to extend it to include this > feature. But I can't promise a deadline, just that I will update the ticket > when it is available. > > In the mean time you might try to use the BLCR interface to define critical > sections. If you are using the C/R thread then this may work (though I have > not tried it): > cr_enter_cs() > cr_leave_cs() > > > + How does ompi-checkpoint operate to checkpoint MPI threads? > > We depend on the Checkpoint/Restart Service (e.g., BLCR) to capture the > whole process image including all threads. So BLCR will capture the state of > all threads when we take the process checkpoint. > > -- Josh > > > > > Regards, > > Nguyen Toan > > _______________________________________________ > > users mailing list > > us...@open-mpi.org > > http://www.open-mpi.org/mailman/listinfo.cgi/users > > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users >