MAP and Performance Reports

The following known issues affect Linaro MAP and Linaro Performance Reports.

  • I/O metrics are not available on some systems, including Cray systems.

  • CPU instruction metrics are only available on x86_64 systems.

  • Thread activity is not sampled while a process is inside an MPI call with a duration spanning multiple samples. This can appear as “uncategorized” (white) time in the Application activity bar, when in Thread view mode. The uncategorized time coincides with long running MPI calls.

  • Linaro MAP and Linaro Performance Reports do not support code that spawns new processes, such as fork, exec and MPI_Comm_spawn. In these cases, Linaro MAP and Linaro Performance Reports only profile the original process.

  • Linaro Performance Reports might fail to finalize a profiling session if the cores are oversubscribed on AArch64 architectures. For example, this occurs when attempting to profile a 64 process MPI program on a machine with only 8 cores. This appears as a hang after finishing a profile.

  • When Linaro Performance Reports needs to access another machine as part of starting MPICH 3 or Intel MPI it attempts to use the ssh secure shell by default. However, this might not always be appropriate if ssh is disabled or running on a different port to the default port 22. If startup fails, see Connecting to compute nodes and remote programs (remote-exec).

  • Linaro MAP and Linaro Performance Reports might fail to finish a profiling session if an MPI application exits using a means other than MPI_Finalize. In this case, try setting FORGE_JOB_EXIT_TIMEOUT_MS to ten minutes, to increase the amount of time MAP has to finish profiling.

  • When profiling a program where it or it’s libraries wrap dlsym/dlopen calls (such as MVAPICH2-GDR), there is a chance that the Linaro MAP sampler library will get stuck in a loop. In this case, try statically linking the Linaro MAP sampler library instead. See Static linking for more details.

  • Due to some missing f08 MPI_Status conversion functions, Linaro MAP and Linaro Performance Reports only support mpi_f08 programs run with Cray MPT 8, Open MPI >= 5.0.0, MPICH >= 4.2.3 and MVAPICH 4.0.

  • Only precompiled mpi_f08 wrappers are supported for MVAPICH 4.0, see MVAPICH.

  • Statically linking against the MPI wrapper library is known to have issues wrapping some mpi_f08 MPI calls with MPICH-based MPIs (i.e. MPICH and Cray MPT). As such, you may not see some MPI calls and the MPI call metrics may not be accurate. We recommend using the precompiled wrappers or linking with the dynamic libraries instead, if possible. See Linking for more details.

  • Linaro MAP and Linaro Performance Reports may have undefined behavior when profiling an application that has been linked against the I/O characterization tool darshan. Unload the darshan module and recompile the application to workaround this issue.