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D11990: Lock-free start of serialized parallel regions 

llvm-svn: 245286
This commit is contained in:
Andrey Churbanov 2015-08-18 10:08:27 +00:00
parent f1ae367a99
commit 92effc4565
1 changed files with 30 additions and 25 deletions
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55
openmp/runtime/src/kmp_runtime.c
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@ -874,24 +874,6 @@ __kmp_reserve_threads( kmp_root_t *root, kmp_team_t *parent_team,
KMP_DEBUG_ASSERT( __kmp_init_serial );
KMP_DEBUG_ASSERT( root && parent_team );
//
// Initial check to see if we should use a serialized team.
//
if ( set_nthreads == 1 ) {
KC_TRACE( 10, ( "__kmp_reserve_threads: T#%d reserving 1 thread; requested %d threads\n",
__kmp_get_gtid(), set_nthreads ));
return 1;
}
if ( ( !get__nested_2(parent_team,master_tid) && (root->r.r_in_parallel
#if OMP_40_ENABLED
&& !enter_teams
#endif /* OMP_40_ENABLED */
) ) || ( __kmp_library == library_serial ) ) {
KC_TRACE( 10, ( "__kmp_reserve_threads: T#%d serializing team; requested %d threads\n",
__kmp_get_gtid(), set_nthreads ));
return 1;
}
//
// If dyn-var is set, dynamically adjust the number of desired threads,
// according to the method specified by dynamic_mode.
@ -1720,23 +1702,47 @@ __kmp_fork_call(
}
#endif
/* determine how many new threads we can use */
__kmp_acquire_bootstrap_lock( &__kmp_forkjoin_lock );
if ( parent_team->t.t_active_level >= master_th->th.th_current_task->td_icvs.max_active_levels ) {
nthreads = 1;
} else {
#if OMP_40_ENABLED
int enter_teams = ((ap==NULL && active_level==0)||(ap && teams_level>0 && teams_level==level));
#endif
nthreads = master_set_numthreads ?
master_set_numthreads : get__nproc_2( parent_team, master_tid ); // TODO: get nproc directly from current task
nthreads = __kmp_reserve_threads(root, parent_team, master_tid, nthreads
// Check if we need to take forkjoin lock? (no need for serialized parallel out of teams construct).
// This code moved here from __kmp_reserve_threads() to speedup nested serialized parallels.
if (nthreads > 1) {
if ( ( !get__nested(master_th) && (root->r.r_in_parallel
#if OMP_40_ENABLED
&& !enter_teams
#endif /* OMP_40_ENABLED */
) ) || ( __kmp_library == library_serial ) ) {
KC_TRACE( 10, ( "__kmp_fork_call: T#%d serializing team; requested %d threads\n",
gtid, nthreads ));
nthreads = 1;
}
}
if ( nthreads > 1 ) {
/* determine how many new threads we can use */
__kmp_acquire_bootstrap_lock( &__kmp_forkjoin_lock );
nthreads = __kmp_reserve_threads(root, parent_team, master_tid, nthreads
#if OMP_40_ENABLED
/* AC: If we execute teams from parallel region (on host), then teams should be created
but each can only have 1 thread if nesting is disabled. If teams called from serial region,
then teams and their threads should be created regardless of the nesting setting. */
, ((ap==NULL && active_level==0) ||
(ap && teams_level>0 && teams_level==level))
, enter_teams
#endif /* OMP_40_ENABLED */
);
if ( nthreads == 1 ) {
// Free lock for single thread execution here;
// for multi-thread execution it will be freed later
// after team of threads created and initialized
__kmp_release_bootstrap_lock( &__kmp_forkjoin_lock );
}
}
}
KMP_DEBUG_ASSERT( nthreads > 0 );
@ -1753,7 +1759,6 @@ __kmp_fork_call(
void * * args = (void**) KMP_ALLOCA( argc * sizeof( void * ) );
#endif /* KMP_OS_LINUX && ( KMP_ARCH_X86 || KMP_ARCH_X86_64 || KMP_ARCH_ARM || KMP_ARCH_AARCH64) */
__kmp_release_bootstrap_lock( &__kmp_forkjoin_lock );
KA_TRACE( 20, ("__kmp_fork_call: T#%d serializing parallel region\n", gtid ));
__kmpc_serialized_parallel(loc, gtid);