CMA and Vader

Hi,

When I run an MPI job using PGI 19.04 I get this warning:

WARNING: Linux kernel CMA support was requested via the
btl_vader_single_copy_mechanism MCA variable, but CMA support is
not available due to restrictive ptrace settings.

The vader shared memory BTL will fall back on another single-copy
mechanism if one is available. This may result in lower performance.

Does this cause lower performance as the warning says? Is there a way to fix this?
I am running Linux Mint 19.1 with Ubuntu 18.04 underneath and the 4.15.0-50-generic kernel.

  • Ron

Hi Ron,

Sorry, but I have not seen this before nor know anything about it. Doing a web search, it appears related to a Linux OS “ptrace_scope” setting now that OpenMPI 3 support zero-copy:

Back-ground:

Other similar reports:


https://groups.io/g/OpenHPC-users/topic/openmpi_and_shared_memory/16489081

-Mat