This commit fixes several threading bugs:
- Add an additional lock to the btl_base_endpoint_t structure to lock
the list of pending frags. This allows the progress function to
attempt to send pending frags without needing to drop/reaquire the
lock. This should provide a small improvement in performance and
fixes a potential race between adding an removing items from the
pending list.
- Ensure fast boxes are only set up once by updating the send count
using atomics when needed and do not set the fast box buffer
pointer until the fast box is set up.
Closesopen-mpi/ompi#1408
Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>
On 32-bit architectures loads/stores of fast box headers may take
multiple instructions. This can lead to a data race between the
sender/receiver when reading/writing the sequence number. This can
lead to a situation where the receiver could process incomplete
data. To fix the issue this commit re-orders the fast box header to
put the sequence number and the tag in the same 32-bits to ensure they
are always loaded/stored together.
Fixes#473
Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>
structure
This structure member was originally used to specify the remote segment
for an RDMA operation. Since the new btl interface no longer uses
desriptors for RDMA this member no longer has a purpose. In addition
to removing these members the local segment information has been
renamed to des_segments/des_segment_count.
This is a large update that does the following:
- Only allocate fast boxes for a peer if a send count threshold
has been reached (default: 16). This will greatly reduce the memory
usage with large numbers of local peers.
- Improve performance by limiting the number of fast boxes that can
be allocated per peer (default: 32). This will reduce the amount
of time spent polling for fast box messages.
- Provide new MCA variables to configure the size, maximum count,
and send count thresholds for fast boxes allocations.
- Updated buffer design to increase the range of message sizes that
can be sent with a fast box.
- Add thread protection around fast box allocation (locks). When
spin locks are available this should be updated to use spin locks.
- Various fixes and cleanup.
This commit was SVN r32774.
The use of restrict in the return type qualifier for mca_btl_vader_reserve_fbox
is being ignored by gnu compiler. for newer gcc, one sees this warning only
with -Wignored-qualifiers set, but for older variants of gcc it was reported
that numerous warning messages about this ignored qualifier were being
generated as vader is being compiled.
The warning reported by gcc is
btl_vader_fbox.h:53:47: warning: type qualifiers ignored on function return type [-Wignored-qualifiers]
static inline mca_btl_vader_fbox_t * restrict mca_btl_vader_reserve_fbox (struct mca_btl_base_endpoint_t *ep, const size_t size)
This commit was SVN r32714.
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.
