[Intel-gfx] [PATCH v2] prime_mmap_coherency: Add return error tests for prime sync ioctl
Chris Wilson
chris at chris-wilson.co.uk
Fri Mar 18 09:53:25 UTC 2016
On Fri, Mar 18, 2016 at 09:44:40AM +0000, Chris Wilson wrote:
> On Thu, Mar 17, 2016 at 06:18:06PM -0300, Tiago Vignatti wrote:
> > +static void test_ioctl_errors(void)
> > +{
> > + int i;
> > + int num_children = 8*sysconf(_SC_NPROCESSORS_ONLN);
> > +
> > + igt_fork_signal_helper();
> > + igt_fork(child, num_children) {
>
> Actually there is a danger here in only using a fork-bomb, we may loose
> out on signal interruptions due to busyspins on the mutex (i.e. the
> contention hiding critical paths, since we crucially rely on timing).
>
> For fun, I would use:
>
> int ncpus = sysconf(_SC_NPROCESSORS_ONLN);
> int num_children;
>
> igt_fork_signal_helper();
> for (int num_children = 1; num_children <= 8 *ncpus; num_children <<= 1) {
> igt_fork(child, num_children) {
> struct timespec start = {};
> while (igt_seconds_elapsed(&start) <= num_children)
> blit_and_cmp();
> }
> }
> igt_waitchildren();
With the bug ofc!
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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