openmp: Add omp_set_num_teams, omp_get_max_teams, omp_[gs]et_teams_thread_limit

OpenMP 5.1 adds env vars and functions to set and query new ICVs used
as fallback if thread_limit or num_teams clauses aren't specified on
teams construct.

The following patch implements those, though further work will be needed:
1) OpenMP 5.1 also changed the num_teams clause, so that it can specify
   both lower and upper limit for how many teams should be created and
   changed the meaning when only one expression is provided, instead of
   num_teams(expr) in 5.0 meaning num_teams(1:expr) in 5.1, it now means
   num_teams(expr:expr), i.e. while previously we could create 1 to expr
   teams, in 5.1 we have some low limit by default equal to the single
   expression provided and may not create fewer teams.
   For host teams (which we don't currently implement efficiently for
   NUMA hosts) we trivially satisfy it now by always honoring what the
   user asked for, but for the offloading teams I think we'll need to
   rethink the APIs; currently teams construct is just a call that returns
   and possibly lowers the number of teams; and whenever possible we try
   to evaluate num_teams/thread_limit already on the target construct
   and the GOMP_teams call just sets the number of teams to the minimum
   of provided and requested teams; for some cases e.g. where target
   is not combined with teams and num_teams expression calls some functions
   etc., we need to call those functions in the target region and so it is
   late to figure number of teams, but also hw could just limit what it
   is willing to create; in that case I'm afraid we need to run the target
   body multiple times and arrange for omp_get_team_num () returning the
   right values
2) we need to finally implement the NUMA handling for GOMP_teams_reg
3) I now realize I haven't added some testcase coverage, will do that
   incrementally
4) libgomp.texi needs updates for these new APIs, but also others like
   the allocator

2021-10-11  Jakub Jelinek  <jakub@redhat.com>

gcc/
	* omp-low.c (omp_runtime_api_call): Handle omp_get_max_teams,
	omp_[sg]et_teams_thread_limit and omp_set_num_teams.
libgomp/
	* omp.h.in (omp_set_num_teams, omp_get_max_teams,
	omp_set_teams_thread_limit, omp_get_teams_thread_limit): Declare.
	* omp_lib.f90.in (omp_set_num_teams, omp_get_max_teams,
	omp_set_teams_thread_limit, omp_get_teams_thread_limit): Declare.
	* omp_lib.h.in (omp_set_num_teams, omp_get_max_teams,
	omp_set_teams_thread_limit, omp_get_teams_thread_limit): Declare.
	* libgomp.h (gomp_nteams_var, gomp_teams_thread_limit_var): Declare.
	* libgomp.map (OMP_5.1): Export omp_get_max_teams{,_},
	omp_get_teams_thread_limit{,_}, omp_set_num_teams{,_,_8_} and
	omp_set_teams_thread_limit{,_,_8_}.
	* icv.c (omp_set_num_teams, omp_get_max_teams,
	omp_set_teams_thread_limit, omp_get_teams_thread_limit): New
	functions.
	* env.c (gomp_nteams_var, gomp_teams_thread_limit_var): Define.
	(omp_display_env): Print OMP_NUM_TEAMS and OMP_TEAMS_THREAD_LIMIT.
	(initialize_env): Handle OMP_NUM_TEAMS and OMP_TEAMS_THREAD_LIMIT env
	vars.
	* teams.c (GOMP_teams_reg): If thread_limit is not specified, use
	gomp_teams_thread_limit_var as fallback if not zero.  If num_teams
	is not specified, use gomp_nteams_var.
	* fortran.c (omp_set_num_teams, omp_get_max_teams,
	omp_set_teams_thread_limit, omp_get_teams_thread_limit): Add
	ialias_redirect.
	(omp_set_num_teams_, omp_set_num_teams_8_, omp_get_max_teams_,
	omp_set_teams_thread_limit_, omp_set_teams_thread_limit_8_,
	omp_get_teams_thread_limit_): New functions.

diff --git a/gcc/omp-low.c b/gcc/omp-low.c
index f7242dfbbca848486752c2700838447e2124b566..057b7ae4866ff1b7c0eee58c83354399cb015884 100644 (file)
--- a/gcc/omp-low.c
+++ b/gcc/omp-low.c
@@ -3953,6 +3953,7 @@ omp_runtime_api_call (const_tree fndecl)
       "get_level",
       "get_max_active_levels",
       "get_max_task_priority",
+      "get_max_teams",
       "get_max_threads",
       "get_nested",
       "get_num_devices",
@@ -3965,6 +3966,7 @@ omp_runtime_api_call (const_tree fndecl)
       "get_proc_bind",
       "get_supported_active_levels",
       "get_team_num",
+      "get_teams_thread_limit",
       "get_thread_limit",
       "get_thread_num",
       "get_wtick",
@@ -3998,8 +4000,10 @@ omp_runtime_api_call (const_tree fndecl)
       "set_dynamic",
       "set_max_active_levels",
       "set_nested",
+      "set_num_teams",
       "set_num_threads",
-      "set_schedule"
+      "set_schedule",
+      "set_teams_thread_limit"
     };
 
   int mode = 0;

diff --git a/libgomp/env.c b/libgomp/env.c
index 69ce1d24ee001f786ae960c185a1092f3b966e18..de45c25d540ef02eca74c5e6110ab440d5f8d8d1 100644 (file)
--- a/libgomp/env.c
+++ b/libgomp/env.c
@@ -90,6 +90,8 @@ unsigned long gomp_places_list_len;
 uintptr_t gomp_def_allocator = omp_default_mem_alloc;
 int gomp_debug_var;
 unsigned int gomp_num_teams_var;
+int gomp_nteams_var;
+int gomp_teams_thread_limit_var;
 bool gomp_display_affinity_var;
 char *gomp_affinity_format_var = "level %L thread %i affinity %A";
 size_t gomp_affinity_format_len;
@@ -1319,6 +1321,9 @@ omp_display_env (int verbose)
           gomp_global_icv.thread_limit_var);
   fprintf (stderr, "  OMP_MAX_ACTIVE_LEVELS = '%u'\n",
           gomp_global_icv.max_active_levels_var);
+  fprintf (stderr, "  OMP_NUM_TEAMS = '%u'\n", gomp_nteams_var);
+  fprintf (stderr, "  OMP_TEAMS_THREAD_LIMIT = '%u'\n",
+          gomp_teams_thread_limit_var);
 
   fprintf (stderr, "  OMP_CANCELLATION = '%s'\n",
           gomp_cancel_var ? "TRUE" : "FALSE");
@@ -1453,6 +1458,8 @@ initialize_env (void)
                                 &gomp_nthreads_var_list,
                                 &gomp_nthreads_var_list_len))
     gomp_global_icv.nthreads_var = gomp_available_cpus;
+  parse_int ("OMP_NUM_TEAMS", &gomp_nteams_var, false);
+  parse_int ("OMP_TEAMS_THREAD_LIMIT", &gomp_teams_thread_limit_var, false);
   bool ignore = false;
   if (parse_bind_var ("OMP_PROC_BIND",
                      &gomp_global_icv.bind_var,

diff --git a/libgomp/fortran.c b/libgomp/fortran.c
index d171c7992eb0f5a43a675cfe0cb1ea7fd0e4eb5e..14b5c8d51dd65b0905ec82621086add96f97fa00 100644 (file)
--- a/libgomp/fortran.c
+++ b/libgomp/fortran.c
@@ -67,6 +67,10 @@ ialias_redirect (omp_get_thread_limit)
 ialias_redirect (omp_set_max_active_levels)
 ialias_redirect (omp_get_max_active_levels)
 ialias_redirect (omp_get_supported_active_levels)
+ialias_redirect (omp_set_num_teams)
+ialias_redirect (omp_get_max_teams)
+ialias_redirect (omp_set_teams_thread_limit)
+ialias_redirect (omp_get_teams_thread_limit)
 ialias_redirect (omp_get_level)
 ialias_redirect (omp_get_ancestor_thread_num)
 ialias_redirect (omp_get_team_size)
@@ -478,6 +482,42 @@ omp_in_final_ (void)
   return omp_in_final ();
 }
 
+void
+omp_set_num_teams_ (const int32_t *num_teams)
+{
+  omp_set_num_teams (*num_teams);
+}
+
+void
+omp_set_num_teams_8_ (const int64_t *num_teams)
+{
+  omp_set_max_active_levels (TO_INT (*num_teams));
+}
+
+int32_t
+omp_get_max_teams_ (void)
+{
+  return omp_get_max_teams ();
+}
+
+void
+omp_set_teams_thread_limit_ (const int32_t *thread_limit)
+{
+  omp_set_teams_thread_limit (*thread_limit);
+}
+
+void
+omp_set_teams_thread_limit_8_ (const int64_t *thread_limit)
+{
+  omp_set_teams_thread_limit (TO_INT (*thread_limit));
+}
+
+int32_t
+omp_get_teams_thread_limit_ (void)
+{
+  return omp_get_teams_thread_limit ();
+}
+
 int32_t
 omp_get_cancellation_ (void)
 {

diff --git a/libgomp/icv.c b/libgomp/icv.c
index 4b4892fb35ed98431fa3c4ee3fc4ccbcbf2354de..b7fad42e5c1d71395bd7bdbd5d4f14687360e0fb 100644 (file)
--- a/libgomp/icv.c
+++ b/libgomp/icv.c
@@ -148,6 +148,32 @@ omp_get_supported_active_levels (void)
   return gomp_supported_active_levels;
 }
 
+void
+omp_set_num_teams (int num_teams)
+{
+  if (num_teams >= 0)
+    gomp_nteams_var = num_teams;
+}
+
+int
+omp_get_max_teams (void)
+{
+  return gomp_nteams_var;
+}
+
+void
+omp_set_teams_thread_limit (int thread_limit)
+{
+  if (thread_limit >= 0)
+    gomp_teams_thread_limit_var = thread_limit;
+}
+
+int
+omp_get_teams_thread_limit (void)
+{
+  return gomp_teams_thread_limit_var;
+}
+
 int
 omp_get_cancellation (void)
 {
@@ -248,6 +274,10 @@ ialias (omp_get_thread_limit)
 ialias (omp_set_max_active_levels)
 ialias (omp_get_max_active_levels)
 ialias (omp_get_supported_active_levels)
+ialias (omp_set_num_teams)
+ialias (omp_get_max_teams)
+ialias (omp_set_teams_thread_limit)
+ialias (omp_get_teams_thread_limit)
 ialias (omp_get_cancellation)
 ialias (omp_get_proc_bind)
 ialias (omp_get_max_task_priority)

diff --git a/libgomp/libgomp.h b/libgomp/libgomp.h
index e8901da1069737cfd8403e1899be5486eec0b853..33a9591285fea104a48faecb04106ca760929f9d 100644 (file)
--- a/libgomp/libgomp.h
+++ b/libgomp/libgomp.h
@@ -458,6 +458,8 @@ extern unsigned long gomp_bind_var_list_len;
 extern void **gomp_places_list;
 extern unsigned long gomp_places_list_len;
 extern unsigned int gomp_num_teams_var;
+extern int gomp_nteams_var;
+extern int gomp_teams_thread_limit_var;
 extern int gomp_debug_var;
 extern bool gomp_display_affinity_var;
 extern char *gomp_affinity_format_var;

diff --git a/libgomp/libgomp.map b/libgomp/libgomp.map
index 460a7a4a34bee53f6c9e140ab690c5de374de0e3..4e5397a39a58801e73e6125aeb7353106defa44c 100644 (file)
--- a/libgomp/libgomp.map
+++ b/libgomp/libgomp.map
@@ -214,6 +214,16 @@ OMP_5.1 {
        omp_display_env;
        omp_display_env_;
        omp_display_env_8_;
+       omp_set_num_teams;
+       omp_set_num_teams_;
+       omp_set_num_teams_8_;
+       omp_get_max_teams;
+       omp_get_max_teams_;
+       omp_set_teams_thread_limit;
+       omp_set_teams_thread_limit_;
+       omp_set_teams_thread_limit_8_;
+       omp_get_teams_thread_limit;
+       omp_get_teams_thread_limit_;
 } OMP_5.0.2;
 
 GOMP_1.0 {

diff --git a/libgomp/omp.h.in b/libgomp/omp.h.in
index d75ee13c16da370de6e2b333e087fb4374c6d696..e0177dca6fbb7ac849d1c9ab2cc7d141da6d14c8 100644 (file)
--- a/libgomp/omp.h.in
+++ b/libgomp/omp.h.in
@@ -261,6 +261,11 @@ extern int omp_get_max_task_priority (void) __GOMP_NOTHROW;
 
 extern void omp_fulfill_event (omp_event_handle_t) __GOMP_NOTHROW;
 
+extern void omp_set_num_teams (int) __GOMP_NOTHROW;
+extern int omp_get_max_teams (void) __GOMP_NOTHROW;
+extern void omp_set_teams_thread_limit (int) __GOMP_NOTHROW;
+extern int omp_get_teams_thread_limit (void) __GOMP_NOTHROW;
+
 extern void *omp_target_alloc (__SIZE_TYPE__, int) __GOMP_NOTHROW;
 extern void omp_target_free (void *, int) __GOMP_NOTHROW;
 extern int omp_target_is_present (const void *, int) __GOMP_NOTHROW;

diff --git a/libgomp/omp_lib.f90.in b/libgomp/omp_lib.f90.in
index 1063eee0c947ee3e2d39f2a179c8b69b173453fe..973b87be80aa22fcfc1d377d95b57672575fdf1a 100644 (file)
--- a/libgomp/omp_lib.f90.in
+++ b/libgomp/omp_lib.f90.in
@@ -564,6 +564,36 @@
           end function omp_get_max_task_priority
         end interface
 
+        interface omp_set_num_teams
+          subroutine omp_set_num_teams (num_teams)
+            integer (4), intent (in) :: num_teams
+          end subroutine omp_set_num_teams
+          subroutine omp_set_num_teams_8 (num_teams)
+            integer (8), intent (in) :: num_teams
+          end subroutine omp_set_num_teams_8
+        end interface
+
+        interface
+          function omp_get_max_teams ()
+            integer (4) :: omp_get_max_teams
+          end function omp_get_max_teams
+        end interface
+
+        interface omp_set_teams_thread_limit
+          subroutine omp_set_teams_thread_limit (thread_limit)
+            integer (4), intent (in) :: thread_limit
+          end subroutine omp_set_teams_thread_limit
+          subroutine omp_set_teams_thread_limit_8 (thread_limit)
+            integer (8), intent (in) :: thread_limit
+          end subroutine omp_set_teams_thread_limit_8
+        end interface
+
+        interface
+          function omp_get_teams_thread_limit ()
+            integer (4) :: omp_get_teams_thread_limit
+          end function omp_get_teams_thread_limit
+        end interface
+
         interface
           subroutine omp_fulfill_event (event)
             use omp_lib_kinds

diff --git a/libgomp/omp_lib.h.in b/libgomp/omp_lib.h.in
index f40321c479bcf07b1bd3af6082668d5f6195e647..d5c02605dd70f2583accf6194b024e8ce9c27f10 100644 (file)
--- a/libgomp/omp_lib.h.in
+++ b/libgomp/omp_lib.h.in
@@ -252,6 +252,10 @@
       external omp_get_max_task_priority
       integer(4) omp_get_max_task_priority
 
+      external omp_set_num_teams, omp_set_teams_thread_limit
+      external omp_get_max_teams, omp_get_teams_thread_limit
+      integer(4) omp_get_max_teams, omp_get_teams_thread_limit
+
       external omp_fulfill_event
 
       external omp_set_affinity_format, omp_get_affinity_format

diff --git a/libgomp/teams.c b/libgomp/teams.c
index 8bac3dba6e456135ea293f87769207d11570102a..9409f8ee6aa7502cf5b20d6ca324862c339d751f 100644 (file)
--- a/libgomp/teams.c
+++ b/libgomp/teams.c
@@ -37,6 +37,8 @@ GOMP_teams_reg (void (*fn) (void *), void *data, unsigned int num_teams,
   (void) flags;
   (void) num_teams;
   unsigned old_thread_limit_var = 0;
+  if (thread_limit == 0)
+    thread_limit = gomp_teams_thread_limit_var;
   if (thread_limit)
     {
       struct gomp_task_icv *icv = gomp_icv (true);
@@ -45,7 +47,7 @@ GOMP_teams_reg (void (*fn) (void *), void *data, unsigned int num_teams,
        = thread_limit > INT_MAX ? UINT_MAX : thread_limit;
     }
   if (num_teams == 0)
-    num_teams = 3;
+    num_teams = gomp_nteams_var ? gomp_nteams_var : 3;
   gomp_num_teams = num_teams;
   for (gomp_team_num = 0; gomp_team_num < num_teams; gomp_team_num++)
     fn (data);