Hello Alina,

Thank you for the information about how the pml components work. I knew that the other components were being opened and ultimately closed in favor of yalla, but I didn't realize that initial open would cause a persistent change in the ompi runtime.

Here's the information you requested about the ib network:

- MOFED version:
We are using the Open Fabrics Software as bundled by RedHat, and my ib network folks say we're running something close to v1.5.4
- ibv_devinfo:
[dshrader@mu0001 examples]$ ibv_devinfo
hca_id: mlx4_0
        transport:                      InfiniBand (0)
        fw_ver:                         2.9.1000
        node_guid:                      0025:90ff:ff16:78d8
        sys_image_guid:                 0025:90ff:ff16:78db
        vendor_id:                      0x02c9
        vendor_part_id:                 26428
        hw_ver:                         0xB0
        board_id:                       SM_2121000001000
        phys_port_cnt:                  1
                port:   1
                        state:                  PORT_ACTIVE (4)
                        max_mtu:                4096 (5)
                        active_mtu:             4096 (5)
                        sm_lid:                 250
                        port_lid:               366
                        port_lmc:               0x00
                        link_layer:             InfiniBand


I still get the seg fault when specifying the hca:

$> mpirun -n 1 -mca btl_openib_receive_queues X,4096,1024:X,12288,512:X,65536,512 -mca btl_openib_if_include mlx4_0 ./hello_c.x Hello, world, I am 0 of 1, (Open MPI v1.10.2, package: Open MPI dshra...@mu-fey.lanl.gov Distribution, ident: 1.10.2, repo rev: v1.10.1-145-g799148f, Jan 21, 2016, 135)
--------------------------------------------------------------------------
mpirun noticed that process rank 0 with PID 10045 on node mu0001 exited on signal 11 (Segmentation fault).
--------------------------------------------------------------------------

I don't know if this helps, but the first time I tried the command I mistyped the hca name. This got me a warning, but no seg fault:

$> mpirun -n 1 -mca btl_openib_receive_queues X,4096,1024:X,12288,512:X,65536,512 -mca btl_openib_if_include ml4_0 ./hello_c.x
--------------------------------------------------------------------------
WARNING: One or more nonexistent OpenFabrics devices/ports were
specified:

  Host:                 mu0001
  MCA parameter:        mca_btl_if_include
  Nonexistent entities: ml4_0

These entities will be ignored.  You can disable this warning by
setting the btl_openib_warn_nonexistent_if MCA parameter to 0.
--------------------------------------------------------------------------
Hello, world, I am 0 of 1, (Open MPI v1.10.2, package: Open MPI dshra...@mu-fey.lanl.gov Distribution, ident: 1.10.2, repo rev: v1.10.1-145-g799148f, Jan 21, 2016, 135)

So, telling the openib btl to use the actual hca didn't get the seg fault to go away, but giving it a dummy value did.

Thanks,
David

On 04/20/2016 08:13 AM, Alina Sklarevich wrote:
Hi David,

I was able to reproduce the issue you reported.

When the command line doesn't specify the components to use, ompi will try to load/open all the ones available (and close them in the end) and then choose the components according to their priority and whether or not they were opened successfully. This means that even if pml yalla was the one running, other components were opened and closed as well.

The parameter you are using - btl_openib_receive_queues, doesn't have an effect on pml yalla. It only affects the openib btl which is used by pml ob1.

Using the verbosity of btl_base_verbose I see that when the segmentation fault happens, the code doesn't reach the phase of unloading the openib btl so perhaps the problem originates there (since pml yalla was already unloaded).

Can you please try adding this mca parameter to your command line to specify the HCA you are using?
-mca btl_openib_if_include <hca>
It made the segv go away for me.

Can you please attach the output of ibv_devinfo and write the MOFED version you are using?

Thank you,
Alina.

On Wed, Apr 20, 2016 at 2:53 PM, Joshua Ladd <jladd.m...@gmail.com <mailto:jladd.m...@gmail.com>> wrote:

    Hi, David

    We are looking into your report.

    Best,

    Josh

    On Tue, Apr 19, 2016 at 4:41 PM, David Shrader <dshra...@lanl.gov
    <mailto:dshra...@lanl.gov>> wrote:

        Hello,

        I have been investigating using XRC on a cluster with a
        mellanox interconnect. I have found that in a certain
        situation I get a seg fault. I am using 1.10.2 compiled with
        gcc 5.3.0, and the simplest configure line that I have found
        that still results in the seg fault is as follows:

        $> ./configure --with-hcoll --with-mxm --prefix=...

        I do have mxm 3.4.3065 and hcoll 3.3.768 installed in to
        system space (/usr/lib64). If I use '--without-hcoll
        --without-mxm,' the seg fault does not happen.

        The seg fault happens even when using examples/hello_c.c, so
        here is an example of the seg fault using it:

        $> mpicc hello_c.c -o hello_c.x
        $> mpirun -n 1 ./hello_c.x
        Hello, world, I am 0 of 1, (Open MPI v1.10.2, package: Open
        MPI dshra...@mu-fey.lanl.gov <mailto:dshra...@mu-fey.lanl.gov>
        Distribution, ident: 1.10.2, repo rev: v1.10.1-145-g799148f,
        Jan 21, 2016, 135)
        $> mpirun -n 1 -mca btl_openib_receive_queues
        X,4096,1024:X,12288,512:X,65536,512
        Hello, world, I am 0 of 1, (Open MPI v1.10.2, package: Open
        MPI dshra...@mu-fey.lanl.gov <mailto:dshra...@mu-fey.lanl.gov>
        Distribution, ident: 1.10.2, repo rev: v1.10.1-145-g799148f,
        Jan 21, 2016, 135)
        
--------------------------------------------------------------------------
        mpirun noticed that process rank 0 with PID 22819 on node
        mu0001 exited on signal 11 (Segmentation fault).
        
--------------------------------------------------------------------------

        The seg fault happens no matter the number of ranks. I have
        tried the above command with '-mca pml_base_verbose,' and it
        shows that I am using the yalla pml:

        $> mpirun -n 1 -mca btl_openib_receive_queues
        X,4096,1024:X,12288,512:X,65536,512 -mca pml_base_verbose 100
        ./hello_c.x
        ...output snipped...
        [mu0001.localdomain:22825] select: component cm not selected /
        finalized
        [mu0001.localdomain:22825] select: component ob1 not selected
        / finalized
        [mu0001.localdomain:22825] select: component yalla selected
        ...output snipped...
        
--------------------------------------------------------------------------
        mpirun noticed that process rank 0 with PID 22825 on node
        mu0001 exited on signal 11 (Segmentation fault).
        
--------------------------------------------------------------------------

        Interestingly enough, if I tell mpirun what pml to use, the
        seg fault goes away. The following command does not get the
        seg fault:

        $> mpirun -n 1 -mca btl_openib_receive_queues
        X,4096,1024:X,12288,512:X,65536,512 -mca pml yalla ./hello_c.x

        Passing either ob1 or cm to '-mca pml' also works. So it seems
        that the seg fault comes about when the yalla pml is chosen by
        default, when mxm/hcoll is involved, and using XRC. I'm not
        sure if mxm is to blame, however, as using '-mca pml cm -mca
        mtl mxm' with the XRC parameters doesn't throw the seg fault.

        Other information...
        OS: RHEL 6.7-based (TOSS)
        OpenFabrics: RedHat provided
        Kernel: 2.6.32-573.8.1.2chaos.ch5.4.x86_64
        Config.log and 'ompi_info --all' are in the tarball
        ompi.tar.bz2 which is attached.

        Is there something else I should be doing with the yalla pml
        when using XRC? Regardless, I hope reporting the seg fault is
        useful.

        Thanks,
        David

-- David Shrader
        HPC-ENV High Performance Computer Systems
        Los Alamos National Lab
        Email: dshrader <at> lanl.gov <http://lanl.gov>


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--
David Shrader
HPC-ENV High Performance Computer Systems
Los Alamos National Lab
Email: dshrader <at> lanl.gov

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