switching:
0 0
/ \ \ / \ \
1 \ \ --> 4 \ \
/ \ \ / \ \
3 2 \ 3 2 \
4 1
(duh). The first form is the bmtree suitable for bcast, but the latter is better for reduce.
Updating default decision function accordingly.
This commit was SVN r15422.
- adding linear algorithm with synchronization for gather.
This algorithm prevents congestion at root process, but introduces
synchronization (serializes non-root processes, but allows messages
to arrive from two processes at the same time).
It performed better than binomial and linear algorithms for large message,
and intermediate and large communicator sizes.
- Updating MPI_Gather decision function to reflect performance results
from MX. I will perform more measurements though - so this one can
change.
This commit was SVN r15165.
- Removing "small" message size limit because it really does not relate to the eager size
accross the board.
Now, the leaf nodes in generalized reduce will use blocking send (DEFAULT/ORIGINAL BEHAVIOR)
either when the maximum number of outstanding requests is 0 or
when the total number of segments is less than the maximum number of outstanding requests.
Otherwise, it will send messages using non-blocking synchronized send operation.
This commit was SVN r14572.
This "feature" is disabled by default and it should not affect the current performance.
In case when the message size is large and segment size is smaller than eager size for particular interface,
the leaf nodes in generalized reduce function can overflood parent nodes by sending all segments without
any synchronization. This can cause the parent to have HIGH number of unexpected messages (think 16MB
message with 1KB segments for example). In case of binomial algorithm root node always has at least one
child which is leaf, so this can potentially affect the root's performance significantly [Especially in
large communicators where root may have quite a few children (binomial tree for example)].
When the segment size is bigger than the eager size, rendezvous protocol ensures that this does
not happen so it is not necessary.
Originally, the problem was exposed in "infinite" bucket allocator clean up time for "small" segment sizes
(which may explain some "deadlocks" on Thunderbird tests).
To prevent this, we allow user to specify mca parameter "--mca coll_tuned_reduce_algorithm_max_requests NUM"
this limits number of outstanding messages from a leaf node in generalized reduce to the parent to NUM.
Messages are sent as non-blocking synchrnous messages, so syncronization happens at "wait" time.
The synchronization actually improved performance of pipeline and binomial algorithm for large message sizes
with 1KB segments over MX, but I need to test it some more to make sure it is consistent.
Since there is no easy way to find out what is "the eager" size for particular btl, I set the limit to 4000B.
If message/individual segment size is greater than 4000B - we will not use this feature. This variable may
or may not be exposed as mca parameter later...
I did not have any problems running it and both "default" and "synchronous" tests passed Intel Reduce* tests
up to 80 processes (over MX).
This commit was SVN r14518.
Per discussions with Brian and Ralph, make a slight correction in
where components are installed. Use $pkglibdir, not $libdir/openmpi,
so that when compiled in the orte trunk, components are installed to
the right directory (because the component search patch is checking
$pkglibdir).
This commit was SVN r14345.
The following SVN revisions from the original message are invalid or
inconsistent and therefore were not cross-referenced:
r14289
This merge adds Checkpoint/Restart support to Open MPI. The initial
frameworks and components support a LAM/MPI-like implementation.
This commit follows the risk assessment presented to the Open MPI core
development group on Feb. 22, 2007.
This commit closes trac:158
More details to follow.
This commit was SVN r14051.
The following SVN revisions from the original message are invalid or
inconsistent and therefore were not cross-referenced:
r13912
The following Trac tickets were found above:
Ticket 158 --> https://svn.open-mpi.org/trac/ompi/ticket/158
In that case, sendcount and sendtype are not valid and we need to use
recvcount and recvtype.
This commit fixes trac:943. Reviewed by Jelena Pjesivac-Grbovic.
This commit was SVN r14022.
The following Trac tickets were found above:
Ticket 943 --> https://svn.open-mpi.org/trac/ompi/ticket/943
- fixing line lengths and some of the comments
- possible bug fix (but I do not think we exposed it in any tests so far)
temporary buffers were allocated as multiples of extent instead of
true_extent + (count -1) * extent.
Everything is still passing Intel tests over tcp and btl mx up to 64 nodes.
This commit was SVN r13956.
Currently 3 algorithms are available:
- non-overlapping, reduce + scatterv, (works for non-commutative operations)
- recursive halving algorithm (copied from basic module)
- ring algorithm (similar to allreduce ring, for large messages)
This commit was SVN r13929.
Algorithm allows user to specify the segment size to be used for computation/communication overlap.
The additional memory requirement for the algorithm is 2 x segment size.
It performed well for (really) large message sizes over MX and it passed intel Allreduce_c and Allreduce_loc_c tests.
This commit was SVN r13832.
- the block sizes are computed in more uniformn way.
The first k blocks may be 1 element larger than the remaining blocks.
The algorithm passed Intel Allreduce_c and Allreduce_loc_c tests, and
IMB-3.2 Allreduce, over TCP and both btl and mtl MX (up to 128 processes).
The algorithm still only supports commutative operations.
This commit was SVN r13738.
outstanding requests can be limited using mca parameters.
The implementation passed Intel, IMB-3.2, and mpi_test_suite tests over
TCP and MX up to 128 processes (64 nodes), on both 32-bit and 64-bit machines.
It is not activated by default, but it should be useful for really large
communicator sizes.
This commit was SVN r13720.
Implementation passed intel: MPI_Reduce_c , MPI_Reduce_loc_c, and MPI_Reduce_user_c tests
over TCP, BTL MX, and MTL MX, as well as, mpi_test_suite Reduce tests (up to 64 nodes).
The algorithm is still not activated by decision function (will be in the near future).
This commit was SVN r13657.
The step used to iterate through buffer was function of true_extent instead of extent.
This may or may not solve ticket #689 because I am still getting failures over btl mx,
but I cannot reproduce failures over mtl mx nor tcp.
This commit was SVN r13459.
- post isends in reverse order of posting irecvs.
if the messages arrive approximately in order, this should
minimize the time spent in matching the requests.
I did not see any performance difference over MX up to 64 nodes, but
the change makes sense and may have some impact when we have (many)
more nodes.
This commit was SVN r13337.
- Allreduce algorithms:
- Recursive doubling is used for small messages (up to 10KB) and can be used for
both commutative and non-commutative operations.
Recursive doubling passed OCC, IMB-3.2, Intel (Allreduce_c, Allreduce_loc_c, and
Allreduce_user_c), mpi_test_suite (Allreduce MIN/MAX, and Allreduce MIN/MAX with
MPI_IN_PLACE) tests on TCP up to 36 nodes and MX up to 64 nodes.
- Ring algorithms performs well for larger messages but cannot be used for
non-commutative operations. It passed the same tests as recursive doubling, except
some of the non-commutative tests in Intel benchmarks Allreduce_loc_c and Allreduce_user_c
(which was expected).
- MPI_Allreduce with new decision function passed all of the tests mentioned above.
- Cleaning up coll_tuned_util. Moving isendrecv to static inline just like sendrecv.
This commit was SVN r13252.
