Re: [igt-dev] [Intel-gfx] [PATCH i-g-t] i915/gem_exec_balancer: Throw a few hangs into the virtual pipelines

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 14/11/2019 19:15, Chris Wilson wrote:
> Although a virtual engine itself has no hang detection; that is on the
> underlying physical engines, it does provide a unique means for clients
> to try and break the system. Try and break it before they do.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> ---
>   tests/i915/gem_exec_balancer.c | 105 +++++++++++++++++++++++++++++++++
>   1 file changed, 105 insertions(+)
> 
> diff --git a/tests/i915/gem_exec_balancer.c b/tests/i915/gem_exec_balancer.c
> index 70c4529b4..86028cfdd 100644
> --- a/tests/i915/gem_exec_balancer.c
> +++ b/tests/i915/gem_exec_balancer.c
> @@ -24,6 +24,7 @@
>   #include <sched.h>
>   
>   #include "igt.h"
> +#include "igt_gt.h"
>   #include "igt_perf.h"
>   #include "i915/gem_ring.h"
>   #include "sw_sync.h"
> @@ -1314,6 +1315,102 @@ static void semaphore(int i915)
>   	gem_quiescent_gpu(i915);
>   }
>   
> +static void set_unbannable(int i915, uint32_t ctx)
> +{
> +	struct drm_i915_gem_context_param p = {
> +		.ctx_id = ctx,
> +		.param = I915_CONTEXT_PARAM_BANNABLE,
> +	};
> +
> +	igt_assert_eq(__gem_context_set_param(i915, &p), 0);
> +}
> +
> +static void hangme(int i915)
> +{
> +	struct drm_i915_gem_exec_object2 batch = {
> +		.handle = batch_create(i915),
> +	};
> +
> +	/*
> +	 * Fill the available engines with hanging virtual engines and verify
> +	 * that execution continues onto the second batch.
> +	 */
> +
> +	for (int class = 1; class < 32; class++) {
> +		struct i915_engine_class_instance *ci;
> +		struct client {
> +			igt_spin_t *spin[2];
> +		} *client;
> +		unsigned int count;
> +		uint32_t bg;
> +
> +		ci = list_engines(i915, 1u << class, &count);
> +		if (!ci)
> +			continue;
> +
> +		if (count < 2) {
> +			free(ci);
> +			continue;
> +		}
> +
> +		client = malloc(sizeof(*client) * count);
> +		igt_assert(client);
> +
> +		for (int i = 0; i < count; i++) {
> +			uint32_t ctx = gem_context_create(i915);
> +			struct client *c = &client[i];
> +			unsigned int flags;
> +
> +			set_unbannable(i915, ctx);
> +			set_load_balancer(i915, ctx, ci, count, NULL);
> +
> +			flags = IGT_SPIN_FENCE_OUT | IGT_SPIN_NO_PREEMPTION;
> +			for (int j = 0; j < ARRAY_SIZE(c->spin); j++)  {
> +				c->spin[j] = igt_spin_new(i915, ctx,
> +							  .flags = flags);
> +				flags = IGT_SPIN_FENCE_OUT;
> +			}
> +
> +			gem_context_destroy(i915, ctx);
> +		}
> +
> +		/* Apply some background context to speed up hang detection */
> +		bg = gem_context_create(i915);
> +		set_engines(i915, bg, ci, count);
> +		for (int i = 0; i < count; i++) {
> +			struct drm_i915_gem_execbuffer2 execbuf = {
> +				.buffers_ptr = to_user_pointer(&batch),
> +				.buffer_count = 1,
> +				.flags = i,
> +				.rsvd1 = bg,
> +			};
> +			gem_execbuf(i915, &execbuf);
> +		}
> +		gem_context_destroy(i915, bg);
> +
> +		for (int i = 0; i < count; i++) {
> +			struct client *c = &client[i];
> +
> +			igt_debug("Waiting for client[%d].spin[%d]\n", i, 0);
> +			gem_sync(i915, c->spin[0]->handle);
> +			igt_assert_eq(sync_fence_status(c->spin[0]->out_fence),
> +				      -EIO);
> +
> +			igt_debug("Waiting for client[%d].spin[%d]\n", i, 1);
> +			gem_sync(i915, c->spin[1]->handle);
> +			igt_assert_eq(sync_fence_status(c->spin[1]->out_fence),
> +				      -EIO);
> +
> +			igt_spin_free(i915, c->spin[0]);
> +			igt_spin_free(i915, c->spin[1]);
> +		}
> +		free(client);
> +	}
> +
> +	gem_close(i915, batch.handle);
> +	gem_quiescent_gpu(i915);
> +}
> +
>   static void smoketest(int i915, int timeout)
>   {
>   	struct drm_i915_gem_exec_object2 batch[2] = {
> @@ -1486,4 +1583,12 @@ igt_main
>   	igt_fixture {
>   		igt_stop_hang_detector();
>   	}
> +
> +	igt_subtest("hang") {
> +		igt_hang_t hang = igt_allow_hang(i915, 0, 0);
> +
> +		hangme(i915);
> +
> +		igt_disallow_hang(i915, hang);
> +	}
>   }
> 

Looks good. But do we need some core helpers to figure out when preempt 
timeout is compiled out?

Regards,

Tvrtko

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