Add a framework to support different types of threading models including
user space thread packages such as Qthreads and argobot:
https://github.com/pmodels/argobotshttps://github.com/Qthreads/qthreads
The default threading model is pthreads. Alternate thread models are
specificed at configure time using the --with-threads=X option.
The framework is static. The theading model to use is selected at
Open MPI configure/build time.
mca/threads: implement Argobots threading layer
config: fix thread configury
- Add double quotations
- Change Argobot to Argobots
config: implement Argobots check
If the poll time is too long, MPI hangs.
This quick fix just sets it to 0, but it is not good for the
Pthreads version. Need to find a good way to abstract it.
Note that even 1 (= 1 millisecond) causes disastrous performance
degradation.
rework threads MCA framework configury
It now works more like the ompi/mca/rte configury,
modulo some edge items that are special for threading package
linking, etc.
qthreads module
some argobots cleanup
Signed-off-by: Noah Evans <noah.evans@gmail.com>
Signed-off-by: Shintaro Iwasaki <siwasaki@anl.gov>
Signed-off-by: Howard Pritchard <howardp@lanl.gov>
This commit updates the entire codebase to use specific opal types for
all atomic variables. This is a change from the prior atomic support
which required the use of the volatile keyword. This is the first step
towards implementing support for C11 atomics as that interface
requires the use of types declared with the _Atomic keyword.
Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>
This commit updates the atomic fifo code to fix a consistency issue
observed on Power9 systems when builtin atomics are used. The cause
was two things: 1) a missing write memory barrier in fifo push, and 2)
a read ordering issue when reading the fifo head non-atomically. This
commit fixes both issues and appears to correct then inconsistency.
Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>
This commit fixes a hang that occurs with debug builds of Open MPI on
aarch64 and power/powerpc systems. When the ll/sc atomics are inline
functions the compiler emits load/store instructions for the function
arguments with -O0. These extra load/store arguments can cause the ll
reservation to be cancelled causing live-lock.
Note that we did attempt to fix this with always_inline but the extra
instructions are stil emitted by the compiler (gcc). There may be
another fix but this has been tested and is working well.
References #3697. Close when applied to v3.0.x and v3.1.x.
Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>
This commit adds a new set of compare-and-exchange functions. These
functions have a signature similar to the functions found in C11. The
old cmpset functions are now deprecated and defined in terms of the
new compare-and-exchange functions. All asm backends have been
updated.
Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>
This commit renames the atomic compare-and-swap functions to indicate
the return value. This is in preperation for adding support for a
compare-and-swap that returns the old value. At the same time the
return type has been changed to bool.
Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>
This change has the side effect of improving the performance of all
atomic data structures (in addition to making the code crrect under a
certain interpretation of the volatile usage).
This commit fixes#3450.
Signed-off-by: George Bosilca <bosilca@icl.utk.edu>
This commit adds implementations for opal_atomic_lifo_pop and
opal_atomic_lifo_push that make use of the load-linked and
store-conditional instruction. These instruction allow for a more
efficient implementation on supported platforms.
Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>
On x86_64 reading a 128-bit value requires multiple instructions.
Under some conditions if the counted pointer counter is read before
the item pointer the fifo can be left in an inconsistent state. This
commit forces the read of the counter to always be read first.
The fifo does not appear to suffer from the same race.
It is possible the compiler can reorder the read of the head item and
the head itself. This could lead to a situation where the item
returned was not really the head item.
- Rename opal_atomic_lifo_t to opal_lifo_t to reflect both atomic and
non-atomic usage. Added new routines (opal_lifo_*_st) for non-atomic
usage as well as routines conditioned off opal_using_threads(). The
atomic versions are always thread safe and the non-atomic are always
not thread safe.
- Add a new atomic lifo implementation that makes use of 128-bit
compare-and-swap. The new implementation should scale better with
larger numbers of threads.
- Add threading unit test for opal_lifo_t.
