Re: [Intel-gfx] [PATCH 2/8] drm/i915/selftests: Add tests for timeslicing virtual engines

From: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
To: Chris Wilson <chris@chris-wilson.co.uk>, intel-gfx@lists.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH 2/8] drm/i915/selftests: Add tests for timeslicing virtual engines
Date: Mon, 18 May 2020 11:12:29 +0100	[thread overview]
Message-ID: <6bbdd286-4a82-6ca5-a4f8-743c17050468@linux.intel.com> (raw)
In-Reply-To: <20200518081440.17948-2-chris@chris-wilson.co.uk>

On 18/05/2020 09:14, Chris Wilson wrote:
> Make sure that we can execute a virtual request on an already busy
> engine, and conversely that we can execute a normal request if the
> engines are already fully occupied by virtual requests.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/gt/selftest_lrc.c | 179 +++++++++++++++++++++++++
>   1 file changed, 179 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/gt/selftest_lrc.c b/drivers/gpu/drm/i915/gt/selftest_lrc.c
> index 824f99c4cc7c..1fc54359bd53 100644
> --- a/drivers/gpu/drm/i915/gt/selftest_lrc.c
> +++ b/drivers/gpu/drm/i915/gt/selftest_lrc.c
> @@ -3766,6 +3766,184 @@ static int live_virtual_mask(void *arg)
>   	return 0;
>   }
>   
> +static int slicein_virtual_engine(struct intel_gt *gt,
> +				  struct intel_engine_cs **siblings,
> +				  unsigned int nsibling)
> +{
> +	struct intel_context *ce;
> +	struct i915_request *rq;
> +	struct igt_spinner spin;
> +	unsigned int n;
> +	int err = 0;
> +
> +	/*
> +	 * Virtual requests must take part in timeslicing on the target engines.
> +	 */
> +
> +	if (igt_spinner_init(&spin, gt))
> +		return -ENOMEM;
> +
> +	for (n = 0; n < nsibling; n++) {
> +		ce = intel_context_create(siblings[n]);
> +		if (IS_ERR(ce)) {
> +			err = PTR_ERR(ce);
> +			goto out;
> +		}
> +
> +		rq = igt_spinner_create_request(&spin, ce, MI_ARB_CHECK);
> +		intel_context_put(ce);
> +
> +		if (IS_ERR(rq)) {
> +			err = PTR_ERR(rq);
> +			goto out;
> +		}
> +
> +		i915_request_add(rq);
> +	}
> +
> +	ce = intel_execlists_create_virtual(siblings, nsibling);
> +	if (IS_ERR(ce)) {
> +		err = PTR_ERR(ce);
> +		goto out;
> +	}
> +
> +	rq = intel_context_create_request(ce);
> +	intel_context_put(ce);
> +	if (IS_ERR(rq)) {
> +		err = PTR_ERR(rq);
> +		goto out;
> +	}
> +
> +	i915_request_get(rq);
> +	i915_request_add(rq);
> +	if (i915_request_wait(rq, 0, HZ / 10) < 0) {
> +		GEM_TRACE_ERR("%s(%s) failed to slice in virtual request\n",
> +			      __func__, rq->engine->name);
> +		GEM_TRACE_DUMP();
> +		intel_gt_set_wedged(gt);
> +		err = -EIO;
> +	}
> +	i915_request_put(rq);
> +
> +out:
> +	igt_spinner_end(&spin);
> +	if (igt_flush_test(gt->i915))
> +		err = -EIO;
> +	igt_spinner_fini(&spin);
> +	return err;
> +}
> +
> +static int sliceout_virtual_engine(struct intel_gt *gt,
> +				   struct intel_engine_cs **siblings,
> +				   unsigned int nsibling)
> +{
> +	struct intel_context *ce;
> +	struct i915_request *rq;
> +	struct igt_spinner spin;
> +	unsigned int n;
> +	int err = 0;
> +
> +	/*
> +	 * Virtual requests must allow others a fair timeslice.
> +	 */
> +
> +	if (igt_spinner_init(&spin, gt))
> +		return -ENOMEM;
> +
> +	for (n = 0; n <= nsibling; n++) { /* oversubscribed */
> +		ce = intel_execlists_create_virtual(siblings, nsibling);
> +		if (IS_ERR(ce)) {
> +			err = PTR_ERR(ce);
> +			goto out;
> +		}
> +
> +		rq = igt_spinner_create_request(&spin, ce, MI_ARB_CHECK);
> +		intel_context_put(ce);
> +
> +		if (IS_ERR(rq)) {
> +			err = PTR_ERR(rq);
> +			goto out;
> +		}
> +
> +		i915_request_add(rq);
> +	}
> +
> +	for (n = 0; !err && n < nsibling; n++) {
> +		ce = intel_context_create(siblings[n]);
> +		if (IS_ERR(ce)) {
> +			err = PTR_ERR(ce);
> +			goto out;
> +		}
> +
> +		rq = intel_context_create_request(ce);
> +		intel_context_put(ce);
> +
> +		if (IS_ERR(rq)) {
> +			err = PTR_ERR(rq);
> +			goto out;
> +		}
> +
> +		i915_request_get(rq);
> +		i915_request_add(rq);
> +		if (i915_request_wait(rq, 0, HZ / 10) < 0) {
> +			GEM_TRACE_ERR("%s(%s) failed to slice out virtual request\n",
> +				      __func__, siblings[n]->name);
> +			GEM_TRACE_DUMP();
> +			intel_gt_set_wedged(gt);
> +			err = -EIO;
> +		}
> +		i915_request_put(rq);
> +	}
> +
> +out:
> +	igt_spinner_end(&spin);
> +	if (igt_flush_test(gt->i915))
> +		err = -EIO;
> +	igt_spinner_fini(&spin);
> +	return err;
> +}
> +
> +static int live_virtual_slice(void *arg)
> +{
> +	struct intel_gt *gt = arg;
> +	struct intel_engine_cs *siblings[MAX_ENGINE_INSTANCE + 1];
> +	unsigned int class, inst;
> +	int err;
> +
> +	if (intel_uc_uses_guc_submission(&gt->uc))
> +		return 0;

Shouldn't the intel_engine_has_timeslices check below be enough? I am 
worried not to silently skip this seemingly pretty generic too much.

> +
> +	for (class = 0; class <= MAX_ENGINE_CLASS; class++) {
> +		unsigned int nsibling;
> +
> +		nsibling = 0;
> +		for (inst = 0; inst <= MAX_ENGINE_INSTANCE; inst++) {
> +			struct intel_engine_cs *engine;
> +
> +			engine = gt->engine_class[class][inst];
> +			if (!engine)
> +				break;

This should be continue I think, to account for vcs0 + vcs2 on Icelake.

> +
> +			if (!intel_engine_has_timeslices(engine))
> +				continue;
> +
> +			siblings[nsibling++] = engine;
> +		}
> +		if (nsibling < 2)
> +			continue;
> +
> +		err = slicein_virtual_engine(gt, siblings, nsibling);
> +		if (err)
> +			return err;
> +
> +		err = sliceout_virtual_engine(gt, siblings, nsibling);
> +		if (err)
> +			return err;
> +	}
> +
> +	return 0;
> +}
> +
>   static int preserved_virtual_engine(struct intel_gt *gt,
>   				    struct intel_engine_cs **siblings,
>   				    unsigned int nsibling)
> @@ -4329,6 +4507,7 @@ int intel_execlists_live_selftests(struct drm_i915_private *i915)
>   		SUBTEST(live_virtual_engine),
>   		SUBTEST(live_virtual_mask),
>   		SUBTEST(live_virtual_preserved),
> +		SUBTEST(live_virtual_slice),
>   		SUBTEST(live_virtual_bond),
>   		SUBTEST(live_virtual_reset),
>   	};
> 

Regards,

Tvrtko
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