We currently save the hostname of a proc when we create the ompi_proc_t for it. This was originally done because the only method we had for discovering the host of a proc was to include that info in the modex, and we had to therefore store it somewhere proc-local. Obviously, this ccarried a memory penalty for storing all those strings, and so we added a "cutoff" parameter so that we wouldn't collect hostnames above a certain number of procs.
Unfortunately, this still results in an 8-byte/proc memory cost as we have a char* pointer in the opal_proc_t that is contained in the ompi_proc_t so that we can store the hostname of the other procs if we fall below the cutoff. At scale, this can consume a fair amount of memory.
With the switch to relying on PMIx, there is no longer a need to cache the proc hostnames. Using the "optional" feature of PMIx_Get, we restrict the retrieval to be purely proc-local - i.e., we retrieve the info either via shared memory or from within the proc-internal hash storage (depending upon the active PMIx components). Thus, the retrieval of a hostname is purely a local operation involving no communication.
All RM's are required to provide a complete hostname map of all procs at startup. Thus, we have full access to all hostnames without including them in a modex or having to cache them on each proc. This allows us to remove the char* pointer from the opal_proc_t, saving us 8-bytes/proc.
Unfortunately, PMIx_Get does not currently support the return of a static pointer to memory. Thus, even though PMIx has the hostname in its memory, it can only return a malloc'd version of it. I have therefore ensured that the return from opal_get_proc_hostname is consistently malloc'd and free'd wherever used. This shouldn't be a burden as the hostname is only used in one of two circumstances:
(a) in an error message
(b) in a verbose output for debugging purposes
Thus, there should be no performance penalty associated with the malloc/free requirement. PMIx will eventually be returning static pointers, and so we can eventually simplify this method and return a "const char*" - but as noted, this really isn't an issue even today.
Signed-off-by: Ralph Castain <rhc@pmix.org>
- Port memchecker call from a1d502c.
- Remove unused memcheck macro variables.
- Some code readability improvements.
- Remove some stray +1's in dynamic comm cleanup.
- Re-add OPAL_ENABLE_DEBUG macro to osc header.
- Cleanup some printf's, and includes.
- Refactor cleanup of dpm_disconnect_objs.
Signed-off-by: Austen Lauria <awlauria@us.ibm.com>
This commit fixes a bug that disabled both the RDMA pipeline and RDMA
protocols in ob1. ob1 was internally caching the values of
opal_leave_pinned and opal_leave_pinned_pipeline at init time. This is
no longer valid as opal_leave_pinned may be set by any call to a btl's
add_procs.
Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>
Fix segfault due to mca_pml_ob1_cuda_need_buffers not handling the case of the
endpoint not being there. Calling mca_bml_get_endpoint() seems to fix the problem.
Fixesopen-mpi/ompi#1402
WHAT: Open our low-level communication infrastructure by moving all necessary components (btl/rcache/allocator/mpool) down in OPAL
All the components required for inter-process communications are currently deeply integrated in the OMPI layer. Several groups/institutions have express interest in having a more generic communication infrastructure, without all the OMPI layer dependencies. This communication layer should be made available at a different software level, available to all layers in the Open MPI software stack. As an example, our ORTE layer could replace the current OOB and instead use the BTL directly, gaining access to more reactive network interfaces than TCP. Similarly, external software libraries could take advantage of our highly optimized AM (active message) communication layer for their own purpose. UTK with support from Sandia, developped a version of Open MPI where the entire communication infrastucture has been moved down to OPAL (btl/rcache/allocator/mpool). Most of the moved components have been updated to match the new schema, with few exceptions (mainly BTLs where I have no way of compiling/testing them). Thus, the completion of this RFC is tied to being able to completing this move for all BTLs. For this we need help from the rest of the Open MPI community, especially those supporting some of the BTLs. A non-exhaustive list of BTLs that qualify here is: mx, portals4, scif, udapl, ugni, usnic.
This commit was SVN r32317.
http://www.open-mpi.org/community/lists/devel/2013/10/13072.php
Add support for pinning GPU Direct RDMA in openib BTL for better small message latency of GPU buffers.
Note that none of this is compiled in unless CUDA-aware support is requested.
This commit was SVN r29680.
configure-time dynamic allocation of flags. The net result for platforms
which only support BTL-based communication is a reduction of 8*nprocs bytes
per process. Platforms which support both MTLs and BTLs will not see
a space reduction, but will now be able to safely run both the MTL and BTL
side-by-side, which will prove useful.
This commit was SVN r29100.
Uses new CUDA IPC support. Also, a few minor changes in PML to take
advantage of it.
This code has no effect unless user asks for it explicitly via
configure arguments. Otherwise, it is either #ifdef'ed out or
not compiled.
This commit was SVN r26039.
