From "3.1 Reducing the number of edges" of this [[ https://hal.science/hal-04136674v1/ | paper ]] - Optimization (b)
Task (dependency) nodes have a `successors` list built upon passed dependency.
Given the following code, B will be added to A's successors list building the graph `A` -> `B`
```
// A
# pragma omp task depend(out: x)
{}
// B
# pragma omp task depend(in: x)
{}
```
In the following code, B is currently added twice to A's successor list
```
// A
# pragma omp task depend(out: x, y)
{}
// B
# pragma omp task depend(in: x, y)
{}
```
This patch removes such dupplicates by checking lastly inserted task in `A` successor list.
Authored by: Romain Pereira (rpereira-dev)
Differential Revision: https://reviews.llvm.org/D158544
omp_all_memory currently has no representation in OMPT.
Adding new dependency flags as suggested by omp-lang issue #3007.
Differential Revision: https://reviews.llvm.org/D111788
This patch implements the "task record and replay" mechanism. The idea is to be able to store tasks and their dependencies in the runtime so that we do not pay the cost of task creation and dependency resolution for future executions. The objective is to improve fine-grained task performance, both for those from "omp task" and "taskloop".
The entry point of the recording phase is __kmpc_start_record_task, and the end of record is triggered by __kmpc_end_record_task.
Tasks encapsulated between a record start and a record end are saved, meaning that the runtime stores their dependencies and structures, referred to as TDG, in order to replay them in subsequent executions. In these TDG replays, we start the execution by scheduling all root tasks (tasks that do not have input dependencies), and there will be no involvement of a hash table to track the dependencies, yet tasks do not need to be created again.
At the beginning of __kmpc_start_record_task, we must check if a TDG has already been recorded. If yes, the function returns 0 and starts to replay the TDG by calling __kmp_exec_tdg; if not, we start to record, and the function returns 1.
An integer uniquely identifies TDGs. Currently, this identifier needs to be incremented manually in the source code. Still, depending on how this feature would eventually be used in the library, the caller function must do it; also, the caller function needs to implement a mechanism to skip the associated region, according to the return value of __kmpc_start_record_task.
Reviewed By: tianshilei1992
Differential Revision: https://reviews.llvm.org/D146642
ATOMIC_VAR_INIT has a trivial definition
`#define ATOMIC_VAR_INIT(value) (value)`,
is deprecated in C17/C++20, and will be removed in newer standards in
newer GCC/Clang (e.g. https://reviews.llvm.org/D144196).
Support for taskwait nowait clause with placeholder for runtime changes.
Reviewed By: cchen, ABataev
Differential Revision: https://reviews.llvm.org/D131830
Intel Inspector uses itt notifications to analyze code execution, and it
reports race conditions in dependent tasks.
This patch fixes the issue notifying Inspector on tasks dependency
synchronizations.
Differential Revision: https://reviews.llvm.org/D123042
In most cases, hidden helper task behave similar as detached tasks. That means,
for example, if we have to wait for detached tasks, we have to do the same thing
for hidden helper tasks as well. This patch adds the missing condition for hidden
helper task accordingly along with detached task.
Reviewed By: AndreyChurbanov
Differential Revision: https://reviews.llvm.org/D107316
New omp_all_memory task dependence type is implemented.
Library recognizes the new type via either
(dependence_address == NULL && dependence_flag == 0x80)
or
(dependence_address == SIZE_MAX).
A task with new dependence type depends on each preceding task
with any dependence type (kind of a dependence barrier).
Differential Revision: https://reviews.llvm.org/D108574
Fix for https://bugs.llvm.org/show_bug.cgi?id=49723.
Eliminated references from task dependency hash to node allocated on stack,
thus eliminated accesses to stale memory. So the node now never freed.
Uncommented assertion which triggered when stale memory accessed.
Removed unneeded ref count increment for stack allocated node.
Differential Revision: https://reviews.llvm.org/D106705
Refactored code of dependence processing and added new inoutset dependence type.
Compiler can set dependence flag to 0x8 when call __kmpc_omp_task_with_deps.
All dependence flags library gets so far and corresponding dependence types:
1 - IN, 2 - OUT, 3 - INOUT, 4 - MUTEXINOUTSET, 8 - INOUTSET.
Differential Revision: https://reviews.llvm.org/D97085
This reverts commit a1f550e052543f75acac9089b760cbc61729131f.
Revert in order to fix backwards compatibility breakage
caused by type size change for task dependence flag.
Refactored code of dependence processing and added new inoutset dependence type.
Compiler can set dependence flag to 0x8 when call __kmpc_omp_task_with_deps.
Size of type of the dependence flag changed from 1 to 4 bytes in clang.
All dependence flags library gets so far and corresponding dependence types:
1 - IN, 2 - OUT, 3 - INOUT, 4 - MUTEXINOUTSET, 8 - INOUTSET.
Differential Revision: https://reviews.llvm.org/D97085
The basic design is to create an outer-most parallel team. It is not a regular team because it is only created when the first hidden helper task is encountered, and is only responsible for the execution of hidden helper tasks. We first use `pthread_create` to create a new thread, let's call it the initial and also the main thread of the hidden helper team. This initial thread then initializes a new root, just like what RTL does in initialization. After that, it directly calls `__kmpc_fork_call`. It is like the initial thread encounters a parallel region. The wrapped function for this team is, for main thread, which is the initial thread that we create via `pthread_create` on Linux, waits on a condition variable. The condition variable can only be signaled when RTL is being destroyed. For other work threads, they just do nothing. The reason that main thread needs to wait there is, in current implementation, once the main thread finishes the wrapped function of this team, it starts to free the team which is not what we want.
Two environment variables, `LIBOMP_NUM_HIDDEN_HELPER_THREADS` and `LIBOMP_USE_HIDDEN_HELPER_TASK`, are also set to configure the number of threads and enable/disable this feature. By default, the number of hidden helper threads is 8.
Here are some open issues to be discussed:
1. The main thread goes to sleeping when the initialization is finished. As Andrey mentioned, we might need it to be awaken from time to time to do some stuffs. What kind of update/check should be put here?
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D77609
The buckets are initialized in __kmp_dephash_create but when they are extended
the memory is allocated but not NULL'd, potentially leaving some buckets
uninitialized after all entries have been copied into the new allocation.
This commit makes sure the buckets are properly initialized with NULL before
copying the entries.
Differential Revision: https://reviews.llvm.org/D95167
This patch partially prepares the runtime source code to be built with
-Wconversion, which should trigger warnings if any implicit conversions
can possibly change a value. For builds done with icc or gcc, all such
warnings are handled in this patch. clang gives a much longer list of
warnings, particularly for sign conversions, which the other compilers
don't report. The -Wconversion flag is commented into cmake files, but
I'm not going to turn it on. If someone thinks it is important, and wants
to fix all the clang warnings, they are welcome to.
Types of changes made here involve either improving the consistency of types
used so that no conversion is needed, or else performing careful explicit
conversions, when we're sure a problem won't arise.
Patch is a combination of changes by Terry Wilmarth and Johnny Peyton.
Differential Revision: https://reviews.llvm.org/D92942
These changes add support for Intel's umonitor/umwait usage in wait
code, for architectures that support those intrinsic functions. Usage of
umonitor/umwait is off by default, but can be turned on by setting the
KMP_USER_LEVEL_MWAIT environment variable.
Differential Revision: https://reviews.llvm.org/D91189
This patch updates the expected results for the GOMP interface patches: D87267, D87269, and D87271.
The taskwait-depend test is changed to really use taskwait-depend and copied to an task_if0-depend test.
To pass the tests, the handling of the return address was fixed.
Differential Revision: https://reviews.llvm.org/D87680
Starting with 787eb0c637b I got spurious segmentation faults for some testcases. I could nail it down to `brel` trying to release the "memory" of the node allocated on the stack of __kmpc_omp_wait_deps. With this patch, you will see the assertion triggering for some of the tests in the test suite.
My proposed solution for the issue is to just patch __kmpc_omp_wait_deps:
```
__kmp_init_node(&node);
- node.dn.on_stack = 1;
+ // the stack owns the node
+ __kmp_node_ref(&node);
```
What do you think?
Reviewed By: AndreyChurbanov
Differential Revision: https://reviews.llvm.org/D84472
Add check of negative gtid before indexing __kmp_threads.
This makes static analyzers happier.
This is the first part of the patch split in two parts.
Differential Revision: https://reviews.llvm.org/D84062
Details:
- nconflicts field initialized;
- formatting fix (moved declaration out of the long line);
- count conflicts in new hash as opposed to old one.
Differential Revision: https://reviews.llvm.org/D68036
Remove all older OMP spec versioning from the runtime and build system.
Patch by Terry Wilmarth
Differential Revision: https://reviews.llvm.org/D64534
llvm-svn: 365963
to reflect the new license. These used slightly different spellings that
defeated my regular expressions.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351648
The omp-tools.h file is generated from the OpenMP spec to ensure that the interface
is implemented as specified.
The other changes are necessary to update the interface implementation to the
final version as published in 5.0.
The omp-tools.h header was previously called ompt.h, currently a copy under this name
is installed for legacy tools.
Patch partially perpared by @sconvent
Reviewers: AndreyChurbanov, hbae, Hahnfeld
Reviewed By: hbae
Tags: #openmp, #ompt
Differential Revision: https://reviews.llvm.org/D55579
llvm-svn: 351197
This patch updates the implementation of the ompt_frame_t, ompt_wait_id_t
and ompt_state_t. The final version of the OpenMP 5.0 spec added the "t"
for these types.
Furthermore the structure for ompt_frame_t changed and allows to specify
that the reenter frame belongs to the runtime.
Patch partially prepared by Simon Convent
Reviewers: hbae
llvm-svn: 349458
This change improves the performance of 376.kdtree by giving the compiler an
opportunity to do inlining and other optimizations for the call path,
__kmpc_omp_task_complete_if0()->__kmp_task_finish(), which is one of the hot
paths in the program; some functions in kmp_taskdeps.cpp were moved to the new
header file, kmp_taskdeps.h to achieve this.
Patch by Hansang Bae
Differential Revision: https://reviews.llvm.org/D51889
llvm-svn: 343138
Some types and callback signatures have changed from TR6 to TR7.
Major changes (only adding signatures and stubs):
(-remove idle callback) done by D48362
-add reduction and dispatch callback
-add get_task_memory and finalize_tool runtime entry points
-ompt_invoker_t becomes ompt_parallel_flag_t
-more types of sync_regions
Patch provided by Simon Convent
Reviewers: hbae, protze.joachim
Differential Revision: https://reviews.llvm.org/D50774
llvm-svn: 341834
These are preliminary changes that attempt to use C++11 Atomics in the runtime.
We are expecting better portability with this change across architectures/OSes.
Here is the summary of the changes.
Most variables that need synchronization operation were converted to generic
atomic variables (std::atomic<T>). Variables that are updated with combined CAS
are packed into a single atomic variable, and partial read/write is done
through unpacking/packing
Patch by Hansang Bae
Differential Revision: https://reviews.llvm.org/D47903
llvm-svn: 336563
As for normal task creation, the task frame addresses need to be stored
for the encountering task.
Differential Revision: https://reviews.llvm.org/D41165
llvm-svn: 321421
This is part of the renaming of data types from OpenMP TR4 to TR6
Patch by Simon Convent
Differential Revision: https://reviews.llvm.org/D39326
llvm-svn: 317435
This is part of the renaming of data types from OpenMP TR4 to TR6
Patch by Simon Convent
Differential Revision: https://reviews.llvm.org/D39326
llvm-svn: 317338
The code is tested to work with latest clang, GNU and Intel compiler. The implementation
is optimized for low overhead when no tool is attached shifting the cost to execution with
tool attached.
This patch does not implement OMPT for libomptarget.
Patch by Simon Convent and Joachim Protze
Differential Revision: https://reviews.llvm.org/D38185
llvm-svn: 317085
