Open MPI logo

Open MPI User's Mailing List Archives

  |   Home   |   Support   |   FAQ   |   all Open MPI User's mailing list

Subject: Re: [OMPI users] mca_pml_ob1_send blocks
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2009-08-25 10:14:18

On Aug 24, 2009, at 2:18 PM, Shaun Jackman wrote:

> I'm seeing MPI_Send block in mca_pml_ob1_send. The packet is shorter
> than the eager transmit limit for shared memory (3300 bytes < 4096
> bytes). I'm trying to determine if MPI_Send is blocking due to a
> deadlock. Will MPI_Send block even when sending a packet eagerly?

It can, yes. Message size is one of multiple factors that can cause
MPI_SEND to block -- so yes, it's even possible for short/eager
messages to block in MPI_SEND.

Can you tell if the corresponding receive has already been posted and
is making progress in the receiver?

Jeff Squyres