[mpich-discuss] One-sided communication: MPI_Win_lock inside MPI_Win_fence

[Rajeev Thakur]

Nesting of synchronization epochs is not allowed. Is there a reason to do it this way?

Rajeev

On May 29, 2012, at 4:28 PM, Ziaul Haque Olive wrote:

> Hello Rajeev,
> 
> The whole code is bit large, and the code is from graph500 benchmark. the bfs_one_sided.c. I am trying to transform it a bit. here is a portion of the code,
> 
> 	MPI_Win_fence(MPI_MODE_NOSUCCEED, queue2_win);
> 	
> 	int ii=0,jj,count=1;
> 	 acc_queue2_win_MPI_BOR_data[ii] = masks[VERTEX_LOCAL(w)/elts_per_queue_bit%ulong_bits];
> 	 acc_queue2_win_MPI_BOR_disp[ii] = VERTEX_LOCAL(w)/elts_per_queue_bit/ulong_bits;
> 	 acc_queue2_win_MPI_BOR_target[ii] = VERTEX_OWNER(w);
> 
> 	MPI_Datatype target_type;
> 	MPI_Type_indexed( count, blength , &acc_queue2_win_MPI_BOR_disp[ii], MPI_UNSIGNED_LONG, &target_type);
> 	MPI_Type_commit(&target_type);
> 	int dest =  acc_queue2_win_MPI_BOR_target[ii];
> 	MPI_Win_lock(MPI_LOCK_EXCLUSIVE, dest, 0, queue2_win );
> 
> 	  MPI_Accumulate(&acc_queue2_win_MPI_BOR_data[ii], count, MPI_UNSIGNED_LONG, dest, 0, 1,target_type, MPI_BOR, queue2_win);
> 
> 
>     MPI_Win_unlock(dest, queue2_win );
> 	MPI_Type_free(&target_type);
> 
> 	MPI_Win_fence(MPI_MODE_NOSUCCEED, queue2_win);
> 
> 
> Let me know if it works.
> 
> Thanks
> Ziaul
> 
> On Tue, May 29, 2012 at 4:13 PM, Rajeev Thakur <thakur at mcs.anl.gov> wrote:
> Can you send the complete program if it is small.
> 
> Rajeev
> 
> On May 29, 2012, at 2:54 PM, Ziaul Haque Olive wrote:
> 
> > for smaller number of processes like 4, i was getting correct result, but for 8, it was providing incorrect result.
> >
> > I tried with and without lock/unlock. without lock/unlock provides correct result all the time.
> >
> > Hello,
> >
> > I am getting incorrect result while using lock/unlock synchronization inside fence. the pattern is as follows,
> >
> >           MPI_Win_fence(win1);
> >               ..........
> >           MPI_Win_lock(exclusive, win1);
> >
> >           MPI_Accumulate(MPI_BOR, win1);
> >
> >           MPI_Win_unlock(win1);
> >
> >           MPI_Win_fence(win1);
> >
> > is it invalid to use lock in this way?
> >
> > Thanks,
> > Ziaul.
> >
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