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Subject: [OMPI devel] PML/ob1 problem
From: Mike Dubman (mike.ompi_at_[hidden])
Date: 2009-02-11 01:01:00


Hello guys,

I'm running some experimental tcp btl which implements rdma GET method and
advertises it in its flags of the btl API.
The btl`s send() method returns rc=1 to select fast path for PML. (this
optimization was added in revision 18551 in v1.3)

It seems that in PML/ob1, mca_pml_ob1_send_request_start_rdma() function
does not treat right such combination (btl GET + fastpath rc>0) and going
into deadlock, i.e.

+++ pml_ob1_sendreq.c +670
At this line, sendreq->req_state is 0

+++ pml_ob1_sendreq.c +800
At this line, if btl has GET method and btl`s send() returned fastpath hint
- the call to mca_pml_ob1_rndv_completion_request() will decrement
sendreq->req_state by one, leaving it to -1.

This value of -1 will keep send_request_pml_complete_check() from completing
request on PML level.

The PML logic (in mca_pml_ob1_send_request_start_rdma) for PUT operation
initializes req_state to "2" in pml_ob1_sendreq.c +791, but leaves req_state
to 0 for GET operations.

Please suggest.

Thanks

Mike.