On Dec 14, 2008, at 8:21 AM, Gabriele Fatigati wrote:
i have a strage problems with OpenMPI 1.2.5 Intel Compiled when i debug my code under Valgrind 3.3. In a very simple ping-pong MPI application, i retrieve strange warnings about MPI Communications, like MPI_Send,MPI_Recv. Valgrind tells me that there are uninitialized values in send/recv buffers, but there are initialized, i'm absolutely sure! There warnings are detected when my application runs over Infiniband net,
This is because IB uses memory that does not come from the memory allocator that Valgrind is aware of (e.g., it may be memory that was allocated by the kernel itself). Hence, since Valgrind is unaware of the memory, it thinks that its contents are undefined. As such, it's quite likely that you're seeing false positives.
The memchecker support in the upcoming v1.3 series made quite a few advancements in the area of valgrind memory checking, and recent versions of libibverbs allow you to compile in valgrind extensions that tell valgrind "this memory is ok" (which prevents these false positives). I'm pretty sure that the OFED install does not enable these libibverbs valgrind extensions; you will likely need your own installation of libibverbs and your verbs plugin (libmthca for you, I think...?) that explicitly has the valgrind extensions enabled.
-- Jeff Squyres Cisco Systems
