llvmbot
commented
5 months ago @llvm/issue-subscribers-openmp
Author: PEREIRA Romain (rpereira-dev)
Something seems wrong with the OMPT `task_schedule` event on untied tasks, please see minimal example bellow
LLVM version
```bash
$ clang --version
clang version 19.0.0git (https://github.com/rpereira-dev/llvm-project ed327625cc1de7f0f71c63f3ae59b6ac621e2c76)
Target: x86_64-unknown-linux-gnu
Thread model: posix
```
main.c
```C
int main(void)
{
# pragma omp parallel
{
# pragma omp single
{
# pragma omp task untied
{}
}
}
return 0;
}
```
OMPT tool used
```bash
git clone -b llvm/untied-schedule https://github.com/rpereira-dev/ompt-dump.git
```
Compiled and run as
```
clang -Wall -Werror -Wextra -fopenmp main.c
OMP_NUM_THREADS=1 OMP_TOOL_LIBRARIES=path/to/libompt_dump.so ./a.out
```
Outputs
```
1 [OMPT] [INFO] OMPT_DUMP: OpenMP 201611 and runtime LLVM OMP version: 5.0.20140926
2 [OMPT] [INFO] Could not register callback 'ompt_callback_device_unload'
3 [OMPT] [INFO] Could not register callback 'ompt_callback_target_map'
4 [OMPT] [INFO] Could not register callback 'ompt_callback_target_map_emi'
5 [OMPT] [INFO] ompt_callback_thread_begin
6 [OMPT] [INFO] ompt_callback_implicit_task(task_data=0x55c7bf5da440)
7 [OMPT] [INFO] ompt_callback_parallel_begin
8 [OMPT] [INFO] ompt_callback_implicit_task(task_data=0x55c7bf5e1280)
9 [OMPT] [INFO] ompt_callback_work
10 [OMPT] [INFO] ompt_callback_task_create(encountering_task_data=0x55c7bf5e1280, new_task_data=0x55c7bf6e3900)
11 [OMPT] [INFO] ompt_callback_task_schedule(prior_task_data=0x55c7bf5e1280, prior_task_status=7, next_task_data=0x55c7bf6e3900)
12 [OMPT] [INFO] ompt_callback_task_schedule(prior_task_data=0x55c7bf6e3900, prior_task_status=7, next_task_data=0x55c7bf5e1280)
13 [OMPT] [INFO] ompt_callback_task_schedule(prior_task_data=0x55c7bf6e3900, prior_task_status=7, next_task_data=0x55c7bf6e3900)
14 [OMPT] [INFO] ompt_callback_task_schedule(prior_task_data=0x55c7bf6e3900, prior_task_status=1, next_task_data=0x55c7bf5e1280)
15 [OMPT] [INFO] ompt_callback_work
16 [OMPT] [INFO] ompt_callback_sync_region
17 [OMPT] [INFO] ompt_callback_sync_region_wait
18 [OMPT] [INFO] ompt_callback_sync_region_wait
19 [OMPT] [INFO] ompt_callback_sync_region
20 [OMPT] [INFO] ompt_callback_implicit_task(task_data=0x55c7bf5e1280)
21 [OMPT] [INFO] ompt_callback_parallel_end
22 [OMPT] [INFO] ompt_callback_implicit_task(task_data=0x55c7bf5da440)
23 [OMPT] [INFO] ompt_callback_thread_end
```
Event Line 11 - The thread switches from its implicit (parent) task `0x55c7bf5e1280` to the untied task `0x55c7bf6e3900`
Event Line 12 - The thread switches from the untied task `0x55c7bf6e3900` to its implicit (parent) task `0x55c7bf5e1280`
Event Line 13 - The thread switches from the untied task `0x55c7bf6e3900` to the same untied task `0x55c7bf5e1280` with the same status - (**ERROR: the current task is `0x55c7bf5e1280`**)
Event Line 14 - [...]
Removing the `untied` clause produces removes events line 13 and 14, which is what we should expect even with `untied` I believe ?
Something seems wrong with the OMPT
task_scheduleevent on untied tasks, please see minimal example bellowLLVM version
main.c
OMPT tool used
Compiled and run as
Outputs
Event Line 11 - The thread switches from its implicit (parent) task
0x55c7bf5e1280to the untied task0x55c7bf6e3900Event Line 12 - The thread switches from the untied task0x55c7bf6e3900to its implicit (parent) task0x55c7bf5e1280Event Line 13 - The thread switches from the untied task0x55c7bf6e3900to the same untied task0x55c7bf5e1280with the same status - (ERROR: the current task is0x55c7bf5e1280) Event Line 14 - [...]Removing the
untiedclause removes events line 13 and 14, which is what we should expect even withuntiedI believe ?