From e62e8ad1ba5701e0e0c1371041cbb677f75ba3fb Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Mon, 13 Feb 2017 17:15:16 +0000 Subject: [PATCH] drm/i915: Add unit tests for the breadcrumb rbtree, wakeups Third retroactive test, make sure that the seqno waiters are woken. v2: Smattering of comments, rearrange code v3: Fix IDLE assert to avoid startup/sleep races Signed-off-by: Chris Wilson Reviewed-by: Tvrtko Ursulin Link: http://patchwork.freedesktop.org/patch/msgid/20170213171558.20942-5-chris@chris-wilson.co.uk --- .../drm/i915/selftests/intel_breadcrumbs.c | 201 ++++++++++++++++++ 1 file changed, 201 insertions(+) diff --git a/drivers/gpu/drm/i915/selftests/intel_breadcrumbs.c b/drivers/gpu/drm/i915/selftests/intel_breadcrumbs.c index 32a27e56c353..d1b99b565500 100644 --- a/drivers/gpu/drm/i915/selftests/intel_breadcrumbs.c +++ b/drivers/gpu/drm/i915/selftests/intel_breadcrumbs.c @@ -259,11 +259,212 @@ out_engines: return err; } +struct igt_wakeup { + struct task_struct *tsk; + atomic_t *ready, *set, *done; + struct intel_engine_cs *engine; + unsigned long flags; +#define STOP 0 +#define IDLE 1 + wait_queue_head_t *wq; + u32 seqno; +}; + +static int wait_atomic(atomic_t *p) +{ + schedule(); + return 0; +} + +static int wait_atomic_timeout(atomic_t *p) +{ + return schedule_timeout(10 * HZ) ? 0 : -ETIMEDOUT; +} + +static bool wait_for_ready(struct igt_wakeup *w) +{ + DEFINE_WAIT(ready); + + set_bit(IDLE, &w->flags); + if (atomic_dec_and_test(w->done)) + wake_up_atomic_t(w->done); + + if (test_bit(STOP, &w->flags)) + goto out; + + for (;;) { + prepare_to_wait(w->wq, &ready, TASK_INTERRUPTIBLE); + if (atomic_read(w->ready) == 0) + break; + + schedule(); + } + finish_wait(w->wq, &ready); + +out: + clear_bit(IDLE, &w->flags); + if (atomic_dec_and_test(w->set)) + wake_up_atomic_t(w->set); + + return !test_bit(STOP, &w->flags); +} + +static int igt_wakeup_thread(void *arg) +{ + struct igt_wakeup *w = arg; + struct intel_wait wait; + + while (wait_for_ready(w)) { + GEM_BUG_ON(kthread_should_stop()); + + intel_wait_init(&wait, w->seqno); + intel_engine_add_wait(w->engine, &wait); + for (;;) { + set_current_state(TASK_UNINTERRUPTIBLE); + if (i915_seqno_passed(intel_engine_get_seqno(w->engine), + w->seqno)) + break; + + if (test_bit(STOP, &w->flags)) /* emergency escape */ + break; + + schedule(); + } + intel_engine_remove_wait(w->engine, &wait); + __set_current_state(TASK_RUNNING); + } + + return 0; +} + +static void igt_wake_all_sync(atomic_t *ready, + atomic_t *set, + atomic_t *done, + wait_queue_head_t *wq, + int count) +{ + atomic_set(set, count); + atomic_set(ready, 0); + wake_up_all(wq); + + wait_on_atomic_t(set, wait_atomic, TASK_UNINTERRUPTIBLE); + atomic_set(ready, count); + atomic_set(done, count); +} + +static int igt_wakeup(void *arg) +{ + I915_RND_STATE(prng); + const int state = TASK_UNINTERRUPTIBLE; + struct intel_engine_cs *engine = arg; + struct igt_wakeup *waiters; + DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); + const int count = 4096; + const u32 max_seqno = count / 4; + atomic_t ready, set, done; + int err = -ENOMEM; + int n, step; + + mock_engine_reset(engine); + + waiters = drm_malloc_gfp(count, sizeof(*waiters), GFP_TEMPORARY); + if (!waiters) + goto out_engines; + + /* Create a large number of threads, each waiting on a random seqno. + * Multiple waiters will be waiting for the same seqno. + */ + atomic_set(&ready, count); + for (n = 0; n < count; n++) { + waiters[n].wq = &wq; + waiters[n].ready = &ready; + waiters[n].set = &set; + waiters[n].done = &done; + waiters[n].engine = engine; + waiters[n].flags = BIT(IDLE); + + waiters[n].tsk = kthread_run(igt_wakeup_thread, &waiters[n], + "i915/igt:%d", n); + if (IS_ERR(waiters[n].tsk)) + goto out_waiters; + + get_task_struct(waiters[n].tsk); + } + + for (step = 1; step <= max_seqno; step <<= 1) { + u32 seqno; + + /* The waiter threads start paused as we assign them a random + * seqno and reset the engine. Once the engine is reset, + * we signal that the threads may begin their wait upon their + * seqno. + */ + for (n = 0; n < count; n++) { + GEM_BUG_ON(!test_bit(IDLE, &waiters[n].flags)); + waiters[n].seqno = + 1 + prandom_u32_state(&prng) % max_seqno; + } + mock_seqno_advance(engine, 0); + igt_wake_all_sync(&ready, &set, &done, &wq, count); + + /* Simulate the GPU doing chunks of work, with one or more + * seqno appearing to finish at the same time. A random number + * of threads will be waiting upon the update and hopefully be + * woken. + */ + for (seqno = 1; seqno <= max_seqno + step; seqno += step) { + usleep_range(50, 500); + mock_seqno_advance(engine, seqno); + } + GEM_BUG_ON(intel_engine_get_seqno(engine) < 1 + max_seqno); + + /* With the seqno now beyond any of the waiting threads, they + * should all be woken, see that they are complete and signal + * that they are ready for the next test. We wait until all + * threads are complete and waiting for us (i.e. not a seqno). + */ + err = wait_on_atomic_t(&done, wait_atomic_timeout, state); + if (err) { + pr_err("Timed out waiting for %d remaining waiters\n", + atomic_read(&done)); + break; + } + + err = check_rbtree_empty(engine); + if (err) + break; + } + +out_waiters: + for (n = 0; n < count; n++) { + if (IS_ERR(waiters[n].tsk)) + break; + + set_bit(STOP, &waiters[n].flags); + } + mock_seqno_advance(engine, INT_MAX); /* wakeup any broken waiters */ + igt_wake_all_sync(&ready, &set, &done, &wq, n); + + for (n = 0; n < count; n++) { + if (IS_ERR(waiters[n].tsk)) + break; + + kthread_stop(waiters[n].tsk); + put_task_struct(waiters[n].tsk); + } + + drm_free_large(waiters); +out_engines: + mock_engine_flush(engine); + return err; +} + int intel_breadcrumbs_mock_selftests(void) { static const struct i915_subtest tests[] = { SUBTEST(igt_random_insert_remove), SUBTEST(igt_insert_complete), + SUBTEST(igt_wakeup), }; struct intel_engine_cs *engine; int err; -- 2.20.1