The main motivation for reusing objects is that it helps to avoid creating and
leaking synchronization clocks in TSan. The reused object will reuse the
synchronization clock in TSan.
Before, new and delete operators were overloaded to get and return memory for
the object from/to the object pool.
This patch replaces the operator overloading with explicit static New/Delete
functions.
Objects for parallel regions and implicit tasks will always be recruited and
returned to the thread-local object pool. Only for explicit task, there is a
chance that an other thread completes the task and will free the object. This
patch optimizes the thread-local New/Delete calls by avoiding locks and only
lock if the pool is empty. Remote threads return the object into a separate
queue.
The chunk size for allocations is now decided based on page size. The objects
will also be aligned to cache lines avoiding false sharing.
This is the first patch in a series to provide better tasking support.
Differential Revision: https://reviews.llvm.org/D103606
This introduces the new `ARCHER_OPTIONS` flag `ignore_serial=0|1` to disable
analysis and logging of memory accesses in the sequential part of the OpenMP
application.
In the sequential part of an OpenMP program no data race is possible, unless
there is non-OpenMP concurrency (such as pthreads, MPI, ...). For the latter
reason, this is not active by default.
Besides reducing the runtime overhead for the sequential part of the program,
this reduces the memory overhead for sequential initialization. In combination
with `flush_shadow=1` this can allow analysis of applications, which run close
to the limit of available memory, but only access smaller parts of shared
memory during each OpenMP parallel region.
A problem for this approach is that Archer only gets active, when the OpenMP
runtime gets initialized, which might be after serial initialization of the
application. In such case, it helps to call for example `omp_get_max_threads()`
at the beginning of main.
Differential Revision: https://reviews.llvm.org/D90473
The tool provides TSAN annotations for OpenMP synchronization. The tool
is activated if no other OMPT tool is loaded.
The tool detects whether the application was built with TSan and rejects
activation according to the OMPT protocol if there is no TSan-rt.
Differential Revision: https://reviews.llvm.org/D45890
Joachim Protze