On 06/30/2011 09:32 AM, tangchen wrote: > hi， > > The case pthread_cond_init/1-2.c sometimes passed, but sometimes failed on my > box. > > OS: RHEL6.1GA x86_64 > Memory: 4GB > CPU: Xeon E5506 2.13GHz, 4 cores > > When it failed, I got the following messages: > > # ./1-2.run-test > Test starting... > Timers option : 200809 > Clock Selection option : 200809 > Starting clock test > Data initialized successfully for CS test. > Sysconf for monotonix clock: 200809 > clock_settime succeeded > Monotonic clock : 200470.244301499 > Default clock : 1310609518.800609262 > Computed diff : 1310409048.556307763 > With monotonic smaller than default > Two threads are created and waiting. > About to change the default clock value. > Checking that both threads have timedout... > The thread was not woken when the clock was changed so as the timeout > expired > Going to simulate this POSIX behavior... > Rechecking that both threads have timedout... > Null attribute cond var timed out > Default attribute cond var did not time out > Default clock was set back using monotonic clock as a reference > Default attribute cond var timedwait return value: 0 > Default attribute cond var exited with a timeout : no > Default attribute cond var had to be signaled : yes > Default attribute cond var exited as signaled : yes > Default attribute cond var spurious wakeups : 0 > Null attribute cond var timedwait return value: 110 > Null attribute cond var exited with a timeout : yes > Null attribute cond var had to be signaled : no > Null attribute cond var exited as signaled : no > Null attribute cond var spurious wakeups : 0 > Test ../../../conformance/interfaces/pthread_cond_init/1-2.c FAILED: > The cond vars use different clocks. > > I think perhaps it has something to do with the scheduler. The case > calls sched_yield(), which calls __switch() directly in the kernel. > But maybe a very short time later, the main thread is scheduled again, > but not any of the child thread. As a result, sometimes the case passed, > and sometimes failed. I'm sorry. Here, I made a mistake. sched_yield() is a system call, which calls schedule() in kernel. It yields the current CPU to other tasks. So why did it sometimes pass, but sometimes fail? But when using sleep(1) instead of sched_yield(), it always passed? Does it have anything to do with multi cpus? > > I replace it with sleep(1), and I think 1 second is long enough > to ensure two children threads is scheduled. and now, the case > always passes. > > Here is the patch, please comment.:) > > > Signed-off-by: Tang Chen <[email protected]> > --- > .../conformance/interfaces/pthread_cond_init/1-2.c | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > > diff --git > a/testcases/open_posix_testsuite/conformance/interfaces/pthread_cond_init/1-2.c > > b/testcases/open_posix_testsuite/conformance/interfaces/pthread_cond_init/1-2.c > index 60ec77b..7f31ca2 100644 > --- > a/testcases/open_posix_testsuite/conformance/interfaces/pthread_cond_init/1-2.c > +++ > b/testcases/open_posix_testsuite/conformance/interfaces/pthread_cond_init/1-2.c > @@ -371,7 +371,7 @@ int do_cs_test(void) > if (ret != 0) { UNRESOLVED(ret, "Unable to unlock a mutex"); > } > > /* Let the others threads run */ > - sched_yield(); > + sleep(1); > > #if VERBOSE > 1 > output("Checking that both threads have timedout...\n"); > @@ -636,4 +636,4 @@ int main(int argc, char * argv[]) > { FAILED("The cond vars use different clocks."); } > > PASSED; > -} > \ No newline at end of file > +}
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