Re: [PATCH] testsuite: pthread: call sched_yield for non-preemptive targets

[Jeff Law via Gcc-patches]

On 6/20/2022 11:51 PM, Alexandre Oliva via Gcc-patches wrote:

Systems without preemptive multi-threading require sched_yield calls
to be placed at points in which a context switch might be needed to
enable the test to complete.

Regstrapped on x86_64-linux-gnu, also tested with a cross to
aarch64-rtems6.  Ok to install?


for  gcc/testsuite/ChangeLog

* gcc.dg/atomic/c11-atomic-exec-4.c: Call sched_yield.
* gcc.dg/atomic/c11-atomic-exec-5.c: Likewise.
* gcc.dg/atomic/pr80640-2.c: Likewise.
* gcc.dg/atomic/pr80640.c: Likewise.
* gcc.dg/atomic/pr81316.c: Likewise.
* gcc.dg/di-sync-multithread.c: Likewise.

OK.

I was hoping this would improve things internally as I know we have 
problems with the c11-atomic-exec-{4,5} and pr80640 testcases with one 
of our simulators that doesn't handle threads well.  But it doesn't seem 
to have helped.  Too bad, it would have been nice to have those tests 
flip to pass consistently.


Jeff

[PATCH] testsuite: pthread: call sched_yield for non-preemptive targets

[Alexandre Oliva via Gcc-patches]

Systems without preemptive multi-threading require sched_yield calls
to be placed at points in which a context switch might be needed to
enable the test to complete.

Regstrapped on x86_64-linux-gnu, also tested with a cross to
aarch64-rtems6.  Ok to install?


for  gcc/testsuite/ChangeLog

* gcc.dg/atomic/c11-atomic-exec-4.c: Call sched_yield.
* gcc.dg/atomic/c11-atomic-exec-5.c: Likewise.
* gcc.dg/atomic/pr80640-2.c: Likewise.
* gcc.dg/atomic/pr80640.c: Likewise.
* gcc.dg/atomic/pr81316.c: Likewise.
* gcc.dg/di-sync-multithread.c: Likewise.
---
 gcc/testsuite/gcc.dg/atomic/c11-atomic-exec-4.c |   12 +---
 gcc/testsuite/gcc.dg/atomic/c11-atomic-exec-5.c |6 +-
 gcc/testsuite/gcc.dg/atomic/pr80640-2.c |6 --
 gcc/testsuite/gcc.dg/atomic/pr80640.c   |6 --
 gcc/testsuite/gcc.dg/atomic/pr81316.c   |9 +++--
 gcc/testsuite/gcc.dg/di-sync-multithread.c  |8 
 6 files changed, 37 insertions(+), 10 deletions(-)

diff --git a/gcc/testsuite/gcc.dg/atomic/c11-atomic-exec-4.c 
b/gcc/testsuite/gcc.dg/atomic/c11-atomic-exec-4.c
index d6bb629f59ffa..669e7c058c39e 100644
--- a/gcc/testsuite/gcc.dg/atomic/c11-atomic-exec-4.c
+++ b/gcc/testsuite/gcc.dg/atomic/c11-atomic-exec-4.c
@@ -32,7 +32,10 @@ test_thread_##NAME (void *arg)   
\
 {  \
   thread_ready = true; \
   for (int i = 0; i < ITER_COUNT; i++) \
-PRE var_##NAME POST;   \
+{  \
+  sched_yield ();  \
+  PRE var_##NAME POST; \
+}  \
   return NULL; \
 }  \
\
@@ -49,9 +52,12 @@ test_main_##NAME (void)  
\
   return 1;
\
 }  \
   while (!thread_ready)
\
-;  \
+sched_yield ();\
   for (int i = 0; i < ITER_COUNT; i++) \
-PRE var_##NAME POST;   \
+{  \
+  PRE var_##NAME POST; \
+  sched_yield ();  \
+}  \
   pthread_join (thread_id, NULL);  \
   if (var_##NAME != (FINAL))   \
 {  \
diff --git a/gcc/testsuite/gcc.dg/atomic/c11-atomic-exec-5.c 
b/gcc/testsuite/gcc.dg/atomic/c11-atomic-exec-5.c
index 692c64ad20737..f8bfa63b4cc8a 100644
--- a/gcc/testsuite/gcc.dg/atomic/c11-atomic-exec-5.c
+++ b/gcc/testsuite/gcc.dg/atomic/c11-atomic-exec-5.c
@@ -53,8 +53,11 @@ test_thread_##NAME (void *arg)   
\
   thread_ready = true; \
   while (!thread_stop) \
 {  \
+  sched_yield ();  \
   var_##NAME = (INIT1);\
+  sched_yield ();  \
   var_##NAME = (INIT2);\
+  sched_yield ();  \
 }  \
   return NULL; \
 }  \
@@ -75,13 +78,14 @@ test_main_##NAME (void) 
\
 }  \
   int num_1_pass = 0, num_1_fail = 0, num_2_pass = 0, num_2_fail = 0;  \
   while (!thread_ready)
\
-;  \
+sched_yield ();