[mpich-devel] MPI_Bsend under MPIU_THREAD_GRANULARITY_PER_OBJECT

[Bob Cernohous]

Start by saying that I have not been involved in the nitty gritty of the 
per-object locking design.

What protects the attached buffer/data structures/request when doing 
multithreaded MPI_Bsend()'s?  All I see in the code path is a (no-op) 
MPIU_THREAD_CS_ENTER(ALLFUNC,).

I have a customer test in which the threads seem to be walking all over 
the request around:

 
/bgusr/bobc/bgq/comm/lib/dev/mpich2/src/mpid/pamid/include/../src/mpid_request.h:259

0000000001088c0c MPIR_Request_complete

 /bgusr/bobc/bgq/comm/lib/dev/mpich2/src/mpi/pt2pt/mpir_request.c:87

000000000106e874 MPIR_Test_impl

        /bgusr/bobc/bgq/comm/lib/dev/mpich2/src/mpi/pt2pt/test.c:62

00000000010188f0 MPIR_Bsend_check_active

        /bgusr/bobc/bgq/comm/lib/dev/mpich2/src/mpi/pt2pt/bsendutil.c:455

0000000001018dc0 MPIR_Bsend_isend

        /bgusr/bobc/bgq/comm/lib/dev/mpich2/src/mpi/pt2pt/bsendutil.c:226

0000000001008734 PMPI_Bsend

        /bgusr/bobc/bgq/comm/lib/dev/mpich2/src/mpi/pt2pt/bsend.c:163

00000000010009c0 00000012.long_branch_r2off.__libc_start_main+0

        :0

000000000130cbc0 start_thread


eg. (fprinting from MPIU_HANDLE_LOG_REFCOUNT_CHANGE)

stderr[8]: set 0x15f8048 (0xac0000ff kind=REQUEST) refcount to 2

stderr[8]: decr 0x15f8048 (0xac0000ff kind=REQUEST) refcount to 1

stderr[8]: decr 0x15f8048 (0xac0000ff kind=REQUEST) refcount to 0

stderr[8]: decr 0x15f8048 (0xac0000ff kind=REQUEST) refcount to -1

stderr[8]: decr 0x15f8048 (0xac0000ff kind=REQUEST) refcount to -2

stderr[8]: decr 0x15f8048 (0xac0000ff kind=REQUEST) refcount to -3

stderr[8]: decr 0x15f8048 (0xac0000ff kind=REQUEST) refcount to -4

stderr[8]: decr 0x15f8048 (0xac0000ff kind=REQUEST) refcount to -5

stderr[8]: decr 0x15f8048 (0xac0000ff kind=REQUEST) refcount to -6

stderr[8]: decr 0x15f8048 (0xac0000ff kind=REQUEST) refcount to -7

stderr[8]: decr 0x15f8048 (0xac0000ff kind=REQUEST) refcount to -8


Bob Cernohous:  (T/L 553) 507-253-6093

BobC at us.ibm.com
IBM Rochester, Building 030-2(C335), Department 61L
3605 Hwy 52 North, Rochester,  MN 55901-7829

> Chaos reigns within.
> Reflect, repent, and reboot.
> Order shall return.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mpich.org/pipermail/devel/attachments/20130425/40896e53/attachment.html>