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From: Mike Houston (mhouston_at_[hidden])
Date: 2007-03-20 18:53:00


Brian Barrett wrote:
> On Mar 20, 2007, at 3:15 PM, Mike Houston wrote:
>
>
>> If I only do gets/puts, things seem to be working correctly with
>> version
>> 1.2. However, if I have a posted Irecv on the target node and issue a
>> MPI_Get against that target, MPI_Test on the posed IRecv causes a
>> segfaults:
>>
>> Anyone have suggestions? Sadly, I need to have IRecv's posted. I'll
>> attempt to find a workaround, but it looks like the posed IRecv is
>> getting all the data of the MPI_Get from the other node. It's like
>> the
>> message tagging is getting ignored. I've never tried posting two
>> different IRecv's with different message tags either...
>>
>
> Hi Mike -
>
> I've spent some time this afternoon looking at the problem and have
> some ideas on what could be happening. I don't think it's a data
> mismatch (the data intended for the IRecv getting delivered to the
> Get), but more a problem with the call to MPI_Test perturbing the
> progress flow of the one-sided engine. I can see one or two places
> where it's possible this could happen, although I'm having trouble
> replicating the problem with any test case I can write. Is it
> possible for you to share the code causing the problem (or some small
> test case)? It would make me feel considerably better if I could
> really understand the conditions required to end up in a seg fault
> state.
>
> Thanks,
>
> Brian
>
Well, I can give you a linux x86 binary if that would do it. The code
is huge as it's part of a much larger system, so there is no such thing
as a simple case at the moment, and the code is in pieces an largely
unrunnable now with all the hacking...

I basically have one thread spinning on an MPI_Test on a posted IRecv
while being used as the target to the MPI_Get. I'll see if I can hack
together a simple version that breaks late tonight. I've just played
with posting a send to that IRecv, issuing the MPI_Get, handshaking and
then posting another IRecv and the MPI_Test continues to eat it, but in
a memcpy:

#0 0x001c068c in memcpy () from /lib/libc.so.6
#1 0x00e412d9 in ompi_convertor_pack (pConv=0x83c1198, iov=0xa0,
out_size=0xaffc1fd8, max_data=0xaffc1fdc) at convertor.c:254
#2 0x00ea265d in ompi_osc_pt2pt_replyreq_send (module=0x856e668,
replyreq=0x83c1180) at osc_pt2pt_data_move.c:411
#3 0x00ea0ebe in ompi_osc_pt2pt_component_fragment_cb
(pt2pt_buffer=0x8573380) at osc_pt2pt_component.c:582
#4 0x00ea1389 in ompi_osc_pt2pt_progress () at osc_pt2pt_component.c:769
#5 0x00aa3019 in opal_progress () at runtime/opal_progress.c:288
#6 0x00ea59e5 in ompi_osc_pt2pt_passive_unlock (module=0x856e668,
origin=1, count=1) at osc_pt2pt_sync.c:60
#7 0x00ea0cd2 in ompi_osc_pt2pt_component_fragment_cb
(pt2pt_buffer=0x856f300) at osc_pt2pt_component.c:688
#8 0x00ea1389 in ompi_osc_pt2pt_progress () at osc_pt2pt_component.c:769
#9 0x00aa3019 in opal_progress () at runtime/opal_progress.c:288
#10 0x00e33f05 in ompi_request_test (rptr=0xaffc2430,
completed=0xaffc2434, status=0xaffc23fc) at request/req_test.c:82
#11 0x00e61770 in PMPI_Test (request=0xaffc2430, completed=0xaffc2434,
status=0xaffc23fc) at ptest.c:52

-Mike