| Message ID | 20191101084940.31838-1-chris@chris-wilson.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/i915/selftests: Start kthreads before stopping | expand |
On Fri, 1 Nov 2019 at 08:50, Chris Wilson <chris@chris-wilson.co.uk> wrote: > > An interesting observation made with our parallel selftests was that on > our small/single cpu systems we would call kthread_stop() before the > kthreads were spawned. If this happens, the kthread is never run at all; > completely bypassing the test. > > A simple yield() from the parent will ensure that all children have the > opportunity to start before we reap them. > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > Cc: Matthew Auld <matthew.auld@intel.com> Reviewed-by: Matthew Auld <matthew.auld@intel.com>
diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c index c6e61564bb5e..62fabc023a83 100644 --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c @@ -345,6 +345,8 @@ static int live_parallel_switch(void *arg) get_task_struct(data[n].tsk); } + yield(); /* start all threads before we kthread_stop() */ + for (n = 0; n < count; n++) { int status; diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_object_blt.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_object_blt.c index ac40c704514e..e8132aca0bb6 100644 --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_object_blt.c +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_object_blt.c @@ -473,6 +473,8 @@ static int igt_threaded_blt(struct drm_i915_private *i915, get_task_struct(tsk[i]); } + yield(); /* start all threads before we kthread_stop() */ + for (i = 0; i < n_cpus; ++i) { int status; diff --git a/drivers/gpu/drm/i915/gt/selftest_hangcheck.c b/drivers/gpu/drm/i915/gt/selftest_hangcheck.c index 8abc0a1d692b..85e9ccf5c304 100644 --- a/drivers/gpu/drm/i915/gt/selftest_hangcheck.c +++ b/drivers/gpu/drm/i915/gt/selftest_hangcheck.c @@ -826,6 +826,8 @@ static int __igt_reset_engines(struct intel_gt *gt, get_task_struct(tsk); } + yield(); /* start all threads before we begin */ + intel_engine_pm_get(engine); set_bit(I915_RESET_ENGINE + id, >->reset.flags); do { diff --git a/drivers/gpu/drm/i915/gt/selftest_lrc.c b/drivers/gpu/drm/i915/gt/selftest_lrc.c index 5e8c365548f0..eb71ac2f992c 100644 --- a/drivers/gpu/drm/i915/gt/selftest_lrc.c +++ b/drivers/gpu/drm/i915/gt/selftest_lrc.c @@ -2252,6 +2252,8 @@ static int smoke_crescendo(struct preempt_smoke *smoke, unsigned int flags) get_task_struct(tsk[id]); } + yield(); /* start all threads before we kthread_stop() */ + count = 0; for_each_engine(engine, smoke->gt, id) { int status; diff --git a/drivers/gpu/drm/i915/selftests/i915_request.c b/drivers/gpu/drm/i915/selftests/i915_request.c index 74788980ca7a..ef350ff3c35c 100644 --- a/drivers/gpu/drm/i915/selftests/i915_request.c +++ b/drivers/gpu/drm/i915/selftests/i915_request.c @@ -465,6 +465,7 @@ static int mock_breadcrumbs_smoketest(void *arg) get_task_struct(threads[n]); } + yield(); /* start all threads before we begin */ msleep(jiffies_to_msecs(i915_selftest.timeout_jiffies)); for (n = 0; n < ncpus; n++) { @@ -1392,6 +1393,7 @@ static int live_breadcrumbs_smoketest(void *arg) idx++; } + yield(); /* start all threads before we begin */ msleep(jiffies_to_msecs(i915_selftest.timeout_jiffies)); out_flush:
An interesting observation made with our parallel selftests was that on our small/single cpu systems we would call kthread_stop() before the kthreads were spawned. If this happens, the kthread is never run at all; completely bypassing the test. A simple yield() from the parent will ensure that all children have the opportunity to start before we reap them. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Matthew Auld <matthew.auld@intel.com> --- drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c | 2 ++ drivers/gpu/drm/i915/gem/selftests/i915_gem_object_blt.c | 2 ++ drivers/gpu/drm/i915/gt/selftest_hangcheck.c | 2 ++ drivers/gpu/drm/i915/gt/selftest_lrc.c | 2 ++ drivers/gpu/drm/i915/selftests/i915_request.c | 2 ++ 5 files changed, 10 insertions(+)