Description
Description
The OpenMP tools interface offers a callback called ompt_callback_work. Here, the parameter work_type can be used to determine the type of work a thread is doing. There are several different values for loops, which can be used to get the schedule for the OpenMP loops.
Right now, LLVM does not report any schedule type. Instead, the value ompt_work_loop is used for every schedule type.
From what I was able to gather in the LLVM source code, only ompt_work_loop is set and no checks for the schedule type are done:
llvm-project/openmp/runtime/src/kmp_dispatch.cpp
Line 1006 in 68f1391
llvm-project/openmp/runtime/src/kmp_sched.cpp
Line 116 in fd2de54
llvm-project/openmp/runtime/src/kmp_csupport.cpp
Line 1922 in fd2de54
The test heaader also includes a TODO to handle the schedule types:
Reproducer
You can compile and run the code down below to reproduce the issue. The program will exit with an assertion error because no schedule type was reported.
$ clang --version
clang version 16.0.6 ([email protected]:llvm/llvm-project.git 7cbf1a2591520c2491aa35339f227775f4d3adf6)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /opt/software/software/LLVM/16.0.6/bin
$ clang -fopenmp error_llvm.c
$ OMP_NUM_THREADS=1 ./a.out
ompt_work_loop detected
ompt_work_loop detected
ompt_work_loop detected
ompt_work_loop detected
ompt_work_loop detected
ompt_work_loop detected
a.out: error_llvm.c:46: void ompt_finalize(ompt_data_t *): Assertion `no_schedule == 0' failed.
[1] 609430 IOT instruction (core dumped) OMP_NUM_THREADS=1 ./a.outSource code:
#include <assert.h>
#include <omp.h>
#include <omp-tools.h>
#include <stdlib.h>
#include <stdio.h>
static int no_schedule = 1;
void
callback_ompt_work( ompt_work_t work_type,
ompt_scope_endpoint_t endpoint,
ompt_data_t* parallel_data,
ompt_data_t* task_data,
uint64_t count,
const void* codeptr_ra )
{
switch ( work_type )
{
case ompt_work_loop:
printf("ompt_work_loop detected\n");
break;
case ompt_work_loop_static:
case ompt_work_loop_dynamic:
case ompt_work_loop_guided:
case ompt_work_loop_other:
no_schedule = 0;
break;
default:
break;
}
}
static int
ompt_initialize( ompt_function_lookup_t lookup,
int initial_device_num,
ompt_data_t* tool_data )
{
ompt_set_callback_t set_cb = ( ompt_set_callback_t )lookup( "ompt_set_callback" );
set_cb( ompt_callback_work, ( ompt_callback_t )&callback_ompt_work );
return 1; /* non-zero indicates success for OMPT runtime. */
}
static void
ompt_finalize( ompt_data_t* tool_data )
{
assert(no_schedule == 0);
}
ompt_start_tool_result_t*
ompt_start_tool( unsigned int omp_version,
const char* runtime_version )
{
static ompt_start_tool_result_t ompt_start_tool_result = { &ompt_initialize,
&ompt_finalize,
ompt_data_none };
return &ompt_start_tool_result;
}
int
main( void )
{
#pragma omp parallel for schedule(static)
for ( unsigned i = 0; i < 100; ++i )
{
}
#pragma omp parallel for schedule(dynamic)
for ( unsigned i = 0; i < 100; ++i )
{
}
#pragma omp parallel for schedule(guided)
for ( unsigned i = 0; i < 100; ++i )
{
}
return 0;
}