Skip to content

Serialize accesses to parallelized syrk functions from multiple calle… #5619

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
martin-frbg merged 1 commit into from
Jan 20, 2026
+71 −0
Merged

Serialize accesses to parallelized syrk functions from multiple calle… #5619

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
71 changes: 71 additions & 0 deletions driver/level3/level3_syrk_threaded.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -504,6 +504,33 @@ static int inner_thread(blas_arg_t *args, BLASLONG *range_m, BLASLONG *range_n,

int CNAME(blas_arg_t *args, BLASLONG *range_m, BLASLONG *range_n, FLOAT *sa, FLOAT *sb, BLASLONG mypos){

#ifdef USE_OPENMP
static omp_lock_t level3_lock, critical_section_lock;
static volatile BLASULONG init_lock = 0, omp_lock_initialized = 0,
parallel_section_left = MAX_PARALLEL_NUMBER;

// Lock initialization; Todo : Maybe this part can be moved to blas_init() in blas_server_omp.c
while(omp_lock_initialized == 0)
{
blas_lock(&init_lock);
{
if(omp_lock_initialized == 0)
{
omp_init_lock(&level3_lock);
omp_init_lock(&critical_section_lock);
omp_lock_initialized = 1;
WMB;
}
blas_unlock(&init_lock);
}
}
#elif defined(OS_WINDOWS)
CRITICAL_SECTION level3_lock;
InitializeCriticalSection((PCRITICAL_SECTION)&level3_lock);
#else
static pthread_mutex_t level3_lock = PTHREAD_MUTEX_INITIALIZER;
#endif

blas_arg_t newarg;

#ifndef USE_ALLOC_HEAP
Expand Down Expand Up @@ -560,6 +587,30 @@ int CNAME(blas_arg_t *args, BLASLONG *range_m, BLASLONG *range_n, FLOAT *sa, FLO
#endif
#endif

#ifdef USE_OPENMP
omp_set_lock(&level3_lock);
omp_set_lock(&critical_section_lock);

parallel_section_left--;

/*
How OpenMP locks works with NUM_PARALLEL
1) parallel_section_left = Number of available concurrent executions of OpenBLAS - Number of currently executing OpenBLAS executions
2) level3_lock is acting like a master lock or barrier which stops OpenBLAS calls when all the parallel_section are currently busy executing other OpenBLAS calls
3) critical_section_lock is used for updating variables shared between threads executing OpenBLAS calls concurrently and for unlocking of master lock whenever required
4) Unlock master lock only when we have not already exhausted all the parallel_sections and allow another thread with a OpenBLAS call to enter
*/
if(parallel_section_left != 0)
omp_unset_lock(&level3_lock);

omp_unset_lock(&critical_section_lock);

#elif defined(OS_WINDOWS)
EnterCriticalSection((PCRITICAL_SECTION)&level3_lock);
#else
pthread_mutex_lock(&level3_lock);
#endif

newarg.m = args -> m;
newarg.n = args -> n;
newarg.k = args -> k;
Expand Down Expand Up @@ -706,5 +757,25 @@ int CNAME(blas_arg_t *args, BLASLONG *range_m, BLASLONG *range_n, FLOAT *sa, FLO
free(job);
#endif

#ifdef USE_OPENMP
omp_set_lock(&critical_section_lock);
parallel_section_left++;

/*
Unlock master lock only when all the parallel_sections are already exhausted and one of the thread has completed its OpenBLAS call
otherwise just increment the parallel_section_left
The master lock is only locked when we have exhausted all the parallel_sections, So only unlock it then and otherwise just increment the count
*/
if(parallel_section_left == 1)
omp_unset_lock(&level3_lock);

omp_unset_lock(&critical_section_lock);

#elif defined(OS_WINDOWS)
LeaveCriticalSection((PCRITICAL_SECTION)&level3_lock);
#else
pthread_mutex_unlock(&level3_lock);
#endif

return 0;
}
Loading