Re: [Intel-gfx] [PATCH] drm/i915/selftests: Check preemption rollback of different ring queue depths

[Mika Kuoppala <mika.kuoppala@linux.intel.com>]

Chris Wilson <chris@chris-wilson.co.uk> writes:

> Like live_unlite_ring, but instead of simply looking at the impact of
> intel_ring_direction(), check that preemption more generally works with
> different depths of queued requests in the ring.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>

Pondering about the sizes of try but I can't make up anything
better.

Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>

> ---
>  drivers/gpu/drm/i915/gt/selftest_lrc.c | 163 +++++++++++++++++++++++++
>  1 file changed, 163 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/gt/selftest_lrc.c b/drivers/gpu/drm/i915/gt/selftest_lrc.c
> index 3d088116a055..530718797848 100644
> --- a/drivers/gpu/drm/i915/gt/selftest_lrc.c
> +++ b/drivers/gpu/drm/i915/gt/selftest_lrc.c
> @@ -2756,6 +2756,168 @@ static int create_gang(struct intel_engine_cs *engine,
>  	return err;
>  }
>  
> +static int __live_preempt_ring(struct intel_engine_cs *engine,
> +			       struct igt_spinner *spin,
> +			       int sz)
> +{
> +	struct intel_context *ce[2] = {};
> +	struct i915_request *rq;
> +	struct igt_live_test t;
> +	int err = 0;
> +	int n;
> +
> +	if (igt_live_test_begin(&t, engine->i915, __func__, engine->name))
> +		return -EIO;
> +
> +	for (n = 0; n < ARRAY_SIZE(ce); n++) {
> +		struct intel_context *tmp;
> +
> +		tmp = intel_context_create(engine);
> +		if (IS_ERR(tmp)) {
> +			err = PTR_ERR(tmp);
> +			goto err_ce;
> +		}
> +
> +		err = intel_context_pin(tmp);
> +		if (err) {
> +			intel_context_put(tmp);
> +			goto err_ce;
> +		}
> +
> +		memset32(tmp->ring->vaddr,
> +			 0xdeadbeef, /* trigger a hang if executed */
> +			 tmp->ring->vma->size / sizeof(u32));
> +
> +		ce[n] = tmp;
> +	}
> +
> +	rq = igt_spinner_create_request(spin, ce[0], MI_ARB_CHECK);
> +	if (IS_ERR(rq)) {
> +		err = PTR_ERR(rq);
> +		goto err_ce;
> +	}
> +
> +	i915_request_get(rq);
> +	rq->sched.attr.priority = I915_PRIORITY_BARRIER;
> +	i915_request_add(rq);
> +
> +	if (!igt_wait_for_spinner(spin, rq)) {
> +		intel_gt_set_wedged(engine->gt);
> +		i915_request_put(rq);
> +		err = -ETIME;
> +		goto err_ce;
> +	}
> +
> +	/* Fill the ring, until we will cause a wrap */
> +	n = 0;
> +	while (ce[0]->ring->tail - rq->wa_tail <= sz) {
> +		struct i915_request *tmp;
> +
> +		tmp = intel_context_create_request(ce[0]);
> +		if (IS_ERR(tmp)) {
> +			err = PTR_ERR(tmp);
> +			i915_request_put(rq);
> +			goto err_ce;
> +		}
> +
> +		i915_request_add(tmp);
> +		intel_engine_flush_submission(engine);
> +		n++;
> +	}
> +	intel_engine_flush_submission(engine);
> +	pr_debug("%s: Filled %d with %d nop tails {size:%x, tail:%x, emit:%x, rq.tail:%x}\n",
> +		 engine->name, sz, n,
> +		 ce[0]->ring->size,
> +		 ce[0]->ring->tail,
> +		 ce[0]->ring->emit,
> +		 rq->tail);
> +	GEM_BUG_ON(intel_ring_direction(ce[0]->ring,
> +					rq->tail,
> +					ce[0]->ring->tail) <= 0);
> +	i915_request_put(rq);
> +
> +	/* Create a second request to preempt the first ring */
> +	rq = intel_context_create_request(ce[1]);
> +	if (IS_ERR(rq)) {
> +		err = PTR_ERR(rq);
> +		goto err_ce;
> +	}
> +
> +	rq->sched.attr.priority = I915_PRIORITY_BARRIER;
> +	i915_request_get(rq);
> +	i915_request_add(rq);
> +
> +	err = wait_for_submit(engine, rq, HZ / 2);
> +	i915_request_put(rq);
> +	if (err) {
> +		pr_err("%s: preemption request was not submited\n",
> +		       engine->name);
> +		err = -ETIME;
> +	}
> +
> +	pr_debug("%s: ring[0]:{ tail:%x, emit:%x }, ring[1]:{ tail:%x, emit:%x }\n",
> +		 engine->name,
> +		 ce[0]->ring->tail, ce[0]->ring->emit,
> +		 ce[1]->ring->tail, ce[1]->ring->emit);
> +
> +err_ce:
> +	intel_engine_flush_submission(engine);
> +	igt_spinner_end(spin);
> +	for (n = 0; n < ARRAY_SIZE(ce); n++) {
> +		if (IS_ERR_OR_NULL(ce[n]))
> +			break;
> +
> +		intel_context_unpin(ce[n]);
> +		intel_context_put(ce[n]);
> +	}
> +	if (igt_live_test_end(&t))
> +		err = -EIO;
> +	return err;
> +}
> +
> +static int live_preempt_ring(void *arg)
> +{
> +	struct intel_gt *gt = arg;
> +	struct intel_engine_cs *engine;
> +	struct igt_spinner spin;
> +	enum intel_engine_id id;
> +	int err = 0;
> +
> +	/*
> +	 * Check that we rollback large chunks of a ring in order to do a
> +	 * preemption event. Similar to live_unlite_ring, but looking at
> +	 * ring size rather than the impact of intel_ring_direction().
> +	 */
> +
> +	if (igt_spinner_init(&spin, gt))
> +		return -ENOMEM;
> +
> +	for_each_engine(engine, gt, id) {
> +		int n;
> +
> +		if (!intel_engine_has_preemption(engine))
> +			continue;
> +
> +		if (!intel_engine_can_store_dword(engine))
> +			continue;
> +
> +		engine_heartbeat_disable(engine);
> +
> +		for (n = 0; n <= 3; n++) {
> +			err = __live_preempt_ring(engine, &spin, n * SZ_4K / 4);
> +			if (err)
> +				break;
> +		}
> +
> +		engine_heartbeat_enable(engine);
> +		if (err)
> +			break;
> +	}
> +
> +	igt_spinner_fini(&spin);
> +	return err;
> +}
> +
>  static int live_preempt_gang(void *arg)
>  {
>  	struct intel_gt *gt = arg;
> @@ -4538,6 +4700,7 @@ int intel_execlists_live_selftests(struct drm_i915_private *i915)
>  		SUBTEST(live_preempt_cancel),
>  		SUBTEST(live_suppress_self_preempt),
>  		SUBTEST(live_chain_preempt),
> +		SUBTEST(live_preempt_ring),
>  		SUBTEST(live_preempt_gang),
>  		SUBTEST(live_preempt_timeout),
>  		SUBTEST(live_preempt_user),
> -- 
> 2.20.1
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