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.
allgather.
The new collectives provide a signifigant performance increase over tuned for
small and medium messages. We are initially setting the priority lower than
tuned until this has had some time to soak in the trunk. Please set
coll_ml_priority to 90 for MTT runs.
Credit for this work goes to Manjunath Gorentla Venkata (ORNL), Pavel Shamis (ORNL),
and Nathan Hjelm (LANL).
Commit details (for reference):
Import ORNL's collectives for MPI_Allreduce, MPI_Reduce, and MPI_Allgather.
We need to take the basesmuma header into account when calculating the
ptpcoll small message thresholds. Add a define to bcol.h indicating the
maximum header size so we can take the header into account while not
making ptpcoll dependent on information from basesmuma.
This resolves an issue with allreduce where ptpcoll overwrites the
header of the next buffer in the basesmuma bank.
Fix reduce and make a sequential collective launcher in coll_ml_inlines.h
The root calculation for reduce was wrong for any root != 0. There are
four possibilities for the root:
- The root is not the current process but is in the current hierarchy. In
this case the root is the index of the global root as specified in the
root vector.
- The root is not the current process and is not in the next level of the
hierarchy. In this case 0 must be the local root since this process will
never communicate with the real root.
- The root is not the current process but will be in next level of the
hierarchy. In this case the current process must be the root.
- I am the root. The root is my index.
Tested with IMB which rotates the root on every call to MPI_Reduce. Consider
IMB the reproducer for the issue this commit solves.
Make the bcast algorithm decision an enumerated variable
Resolve various asset failures when destructing coll ml requests.
Two issues:
- Always reset the request to be invalid before returning it to the
free list. This will avoid an asset in ompi_request_t's destructor.
OMPI_REQUEST_FINI does this (and also releases the fortran handle
index).
- Never explicitly construct or destruct the superclass of an opal
object. This screws up the class function tables and will cause
either an assert failure or a segmentation fault when destructing
coll ml requests.
Cleanup allgather.
I removed the duplicate non-blocking and blocking functions and modeled
the cleanup after what I found in allreduce. Also cleaned up the code
somewhat.
Don't bother copying from the send to the recieve buffer in
bcol_basesmuma_allreduce_intra_fanin_fanout if the pointers are the
same.
The eliminates a warning about memcpy and aliasing and avoids an
unnecessary call to memcpy.
Alwasy call CHECK_AND_RELEASE on memsync collectives.
There was a call to OBJ_RELEASE on the collective communicator but
because CHECK_AND_RECYLCE was never called there was not matching call
to OBJ_RELEASE. This caused coll ml to leak communicators.
Make allreduce use the sequential collective launcher in coll_ml_inlines.h
Just launch the next collective in the component progress.
I am a little unsure about this patch. There appears to be some sort
of race between collectives that causes buffer exhaustion in some cases
(IMB Allreduce is a reproducer). Changing progress to only launch the
next bcol seems to resolve the issue but might not be the best fix.
Note that I see little-no performance penalty for this change.
Fix allreduce when there are extra sources.
There was an issue with the buffer offset calculation when there are
extra sources. In the case of extra sources == 1 the offset was set
to buffer_size (just past the header of the next buffer). I adjusted
the buffer size to take into accoun the maximum header size (see the
earlier commit that added this) and simplified the offset calculation.
Make reduce/allreduce non-blocking. This is required for MPI_Comm_idup
to work correctly.
This has been tested with various layouts using the ibm testsuite and
imb and appears to have the same performance as the old blocking version.
Fix allgather for non-contiguous layouts and simplify parsing the
topology.
Some things in this patch:
- There were several comments to the effect that level 0 of the
hierarchy MUST contain all of the ranks. At least one function
made this assumption but it was not true. I changed the sbgp
components and the coll ml initization code to enforce this
requirement.
- Ensure that hierarchy level 0 has the ranks in the correct
scatter gather order. This removes the need for a separate
sort list and fixes the offset calculation for allgather.
- There were several passes over the hierarchy to determine
properties of the hierarchy. I eliminated these extra passes
and the memory allocation associated with them and calculate the
tree properties on the fly. The same DFS recursion also handles
the re-order of level 0.
All these changes have been verified with MPI_Allreduce, MPI_Reduce, and
MPI_Allgather. All functions now pass all IBM/Open MPI, and IMB tests.
coll/ml: correct pointer usage for MPI_BOTTOM
Since contiguous datatypes are copied via memcpy (bypassing the convertor) we
need to adjust for the lb of the datatype. This corrects problems found testing
code that uses MPI_BOTTOM (NULL) as the send pointer.
Add fallback collectives for allreduce and reduce.
cmr=v1.7.5:reviewer=pasha
This commit was SVN r30363.
Features:
- Support for an override parameter file (openmpi-mca-param-override.conf).
Variable values in this file can not be overridden by any file or environment
value.
- Support for boolean, unsigned, and unsigned long long variables.
- Support for true/false values.
- Support for enumerations on integer variables.
- Support for MPIT scope, verbosity, and binding.
- Support for command line source.
- Support for setting variable source via the environment using
OMPI_MCA_SOURCE_<var name>=source (either command or file:filename)
- Cleaner API.
- Support for variable groups (equivalent to MPIT categories).
Notes:
- Variables must be created with a backing store (char **, int *, or bool *)
that must live at least as long as the variable.
- Creating a variable with the MCA_BASE_VAR_FLAG_SETTABLE enables the use of
mca_base_var_set_value() to change the value.
- String values are duplicated when the variable is registered. It is up to
the caller to free the original value if necessary. The new value will be
freed by the mca_base_var system and must not be freed by the user.
- Variables with constant scope may not be settable.
- Variable groups (and all associated variables) are deregistered when the
component is closed or the component repository item is freed. This
prevents a segmentation fault from accessing a variable after its component
is unloaded.
- After some discussion we decided we should remove the automatic registration
of component priority variables. Few component actually made use of this
feature.
- The enumerator interface was updated to be general enough to handle
future uses of the interface.
- The code to generate ompi_info output has been moved into the MCA variable
system. See mca_base_var_dump().
opal: update core and components to mca_base_var system
orte: update core and components to mca_base_var system
ompi: update core and components to mca_base_var system
This commit also modifies the rmaps framework. The following variables were
moved from ppr and lama: rmaps_base_pernode, rmaps_base_n_pernode,
rmaps_base_n_persocket. Both lama and ppr create synonyms for these variables.
This commit was SVN r28236.
It appears the problem was not with the command line parser but the rsh plm. I don't know why this problem was not occuring before the command line parser changes but it appears to be resolved now.
This commit was SVN r27527.
The following SVN revision numbers were found above:
r27451 --> open-mpi/ompi@d59034e6ef
r27456 --> open-mpi/ompi@ecdbf34937
The project includes following components and frameworks:
- ML Collective component
- NETPATTERNS and COMMPATTERNS common components
- BCOL framework
- SBGP framework
Note: By default the ML collective component is disabled. In order to enable
new collectives user should bump up the priority of ml component (coll_ml_priority)
=============================================
Primary Contributors (in alphabetical order):
Ishai Rabinovich (Mellanox)
Joshua S. Ladd (ORNL / Mellanox)
Manjunath Gorentla Venkata (ORNL)
Mike Dubman (Mellanox)
Noam Bloch (Mellanox)
Pavel (Pasha) Shamis (ORNL / Mellanox)
Richard Graham (ORNL / Mellanox)
Vasily Filipov (Mellanox)
This commit was SVN r27078.
