diff mbox

[gomp4.5] depend nowait support for target

Message ID 20151113101841.GL5675@tucnak.redhat.com
State New
Headers show

Commit Message

Jakub Jelinek Nov. 13, 2015, 10:18 a.m. UTC 
On Thu, Nov 12, 2015 at 11:51:33PM +0300, Ilya Verbin wrote:
> I'm unable to reproduce the hang (have tried various values of OMP_NUM_THREADS).
> The testcase just aborts at (a != 50 || b != 4 || c != 20), because
> a == 37, b == 12, c == 40.

The hang has been with a fprintf (stderr, "...\n"); inside of the parallel
regions.  Anyway, still can't reproduce target-32.c crash, the target-33.c
abort is due to thinko (a, b, c were firstprivate in the explicit tasks, so
no wonder it could see the previous values).  See the following incremental
patch.

> BTW, don't know is this a bug or not:
> Conditional jump or move depends on uninitialised value(s)
>    at 0x4C2083D: priority_queue_insert (priority_queue.h:347)
>    by 0x4C24DF9: GOMP_PLUGIN_target_task_completion (task.c:678)

This is due to uninitialized task->priority for the target task.  See below.

Now I'm fighting target-34.c test hangs, strangely it hangs even with host
fallback.

For the offloading case, I actually see a problematic spot, namely that
GOMP_PLUGIN_target_task_completion could finish too early, and get the
task_lock before the thread that run the gomp_target_task_fn doing map_vars
+ async_run for it.  Bet I need to add further ttask state kinds and deal
with that case (so GOMP_PLUGIN_target_task_completion would just take the
task lock and tweak ttask state if it has not been added to the queues
yet).
Plus I think I want to improve the case where we are not waiting, in
gomp_create_target_task if not waiting for dependencies actually schedule
manually the gomp_target_task_fn.



	Jakub
diff mbox

Patch

--- libgomp/testsuite/libgomp.c/target-33.c	2015-11-12 16:20:14.000000000 +0100
+++ libgomp/testsuite/libgomp.c/target-33.c	2015-11-13 09:45:27.174427034 +0100
@@ -61,10 +61,10 @@ 
     a = a + 4;
     c >>= 1;
   }
-  #pragma omp task if (0) depend (in: d[3], d[4])
+  #pragma omp task if (0) depend (in: d[3], d[4]) shared (a, b, c)
   if (a != 50 || b != 4 || c != 20)
     abort ();
-  #pragma omp task
+  #pragma omp task shared (a)
   a += 50;
   #pragma omp target nowait map (tofrom: b)
   b++;
--- libgomp/task.c	2015-11-12 16:24:19.127548800 +0100
+++ libgomp/task.c	2015-11-13 10:53:19.525519366 +0100
@@ -538,6 +538,7 @@ 
 				  + sizeof (unsigned short))
 		      + tgt_size);
   gomp_init_task (task, parent, gomp_icv (false));
+  task->priority = 0;
   task->kind = GOMP_TASK_WAITING;
   task->in_tied_task = parent->in_tied_task;
   task->taskgroup = taskgroup;
--- libgomp/testsuite/libgomp.c/target-34.c.jj	2015-11-13 08:54:42.607799433 +0100
+++ libgomp/testsuite/libgomp.c/target-34.c	2015-11-13 08:54:37.865866795 +0100
@@ -0,0 +1,12 @@ 
+#define main do_main
+#include "target-33.c"
+#undef main
+
+int
+main ()
+{
+  #pragma omp parallel
+  #pragma omp single
+  do_main ();
+  return 0;
+}