Re: [PATCH 7/7] drm/i915/guc: Selftest for stealing of guc ids

From: John Harrison <john.c.harrison@intel.com>
To: Matthew Brost <matthew.brost@intel.com>,
	<intel-gfx@lists.freedesktop.org>,
	<dri-devel@lists.freedesktop.org>
Cc: daniele.ceraolospurio@intel.com
Subject: Re: [PATCH 7/7] drm/i915/guc: Selftest for stealing of guc ids
Date: Fri, 10 Dec 2021 17:33:02 -0800	[thread overview]
Message-ID: <111dd483-dff5-2e60-2913-e6bacf35dda9@intel.com> (raw)
In-Reply-To: <20211211005612.8575-8-matthew.brost@intel.com>

On 12/10/2021 16:56, Matthew Brost wrote:
> Testing the stealing of guc ids is hard from user spaec as we have 64k
spaec -> space

> guc_ids. Add a selftest, which artificially reduces the number of guc
> ids, and forces a steal. Details of test has comment in code so will not
has -> are

But would a copy&paste really be so hard? It is useful to be able to 
read what a patch does from the commit log and not have to delve inside 
every time.

> repeat here.
>
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> ---
>   drivers/gpu/drm/i915/gt/uc/intel_guc.h        |  12 ++
>   .../gpu/drm/i915/gt/uc/intel_guc_submission.c |  15 +-
>   drivers/gpu/drm/i915/gt/uc/selftest_guc.c     | 171 ++++++++++++++++++
>   3 files changed, 193 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> index 1cb46098030d..307380a2e2ff 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> @@ -94,6 +94,11 @@ struct intel_guc {
>   		 * @guc_ids: used to allocate new guc_ids, single-lrc
>   		 */
>   		struct ida guc_ids;
> +		/**
> +		 * @num_guc_ids: Number of guc_ids, selftest feature to be able
> +		 * to reduce this number of test.
of test -> while testing

Should have a CONFIG_SELFTEST around it? And define a wrapper that is 
GUC_MAX_LRC_DESCRIPTORS or num_guc_ids as appropriate.

> +		 */
> +		int num_guc_ids;
>   		/**
>   		 * @guc_ids_bitmap: used to allocate new guc_ids, multi-lrc
>   		 */
> @@ -202,6 +207,13 @@ struct intel_guc {
>   		 */
>   		struct delayed_work work;
>   	} timestamp;
> +
> +#ifdef CONFIG_DRM_I915_SELFTEST
> +	/**
> +	 * @number_guc_id_stole: The number of guc_ids that have been stole
> +	 */
> +	int number_guc_id_stole;
stole -> stolen (in all three cases)

> +#endif
>   };
>   
>   static inline struct intel_guc *log_to_guc(struct intel_guc_log *log)
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> index 96fcf869e3ff..57019b190bfb 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -145,7 +145,7 @@ guc_create_parallel(struct intel_engine_cs **engines,
>    * use should be low and 1/16 should be sufficient. Minimum of 32 guc_ids for
>    * multi-lrc.
>    */
> -#define NUMBER_MULTI_LRC_GUC_ID		(GUC_MAX_LRC_DESCRIPTORS / 16)
> +#define NUMBER_MULTI_LRC_GUC_ID(guc)	(guc->submission_state.num_guc_ids / 16)
And keep the original definition for the non CONFIG_SELFTEST case?

>   
>   /*
>    * Below is a set of functions which control the GuC scheduling state which
> @@ -1775,7 +1775,7 @@ int intel_guc_submission_init(struct intel_guc *guc)
>   		  destroyed_worker_func);
>   
>   	guc->submission_state.guc_ids_bitmap =
> -		bitmap_zalloc(NUMBER_MULTI_LRC_GUC_ID, GFP_KERNEL);
> +		bitmap_zalloc(NUMBER_MULTI_LRC_GUC_ID(guc), GFP_KERNEL);
>   	if (!guc->submission_state.guc_ids_bitmap)
>   		return -ENOMEM;
>   
> @@ -1869,13 +1869,13 @@ static int new_guc_id(struct intel_guc *guc, struct intel_context *ce)
>   
>   	if (intel_context_is_parent(ce))
>   		ret = bitmap_find_free_region(guc->submission_state.guc_ids_bitmap,
> -					      NUMBER_MULTI_LRC_GUC_ID,
> +					      NUMBER_MULTI_LRC_GUC_ID(guc),
>   					      order_base_2(ce->parallel.number_children
>   							   + 1));
>   	else
>   		ret = ida_simple_get(&guc->submission_state.guc_ids,
> -				     NUMBER_MULTI_LRC_GUC_ID,
> -				     GUC_MAX_LRC_DESCRIPTORS,
> +				     NUMBER_MULTI_LRC_GUC_ID(guc),
> +				     guc->submission_state.num_guc_ids,
>   				     GFP_KERNEL | __GFP_RETRY_MAYFAIL |
>   				     __GFP_NOWARN);
>   	if (unlikely(ret < 0))
> @@ -1941,6 +1941,10 @@ static int steal_guc_id(struct intel_guc *guc, struct intel_context *ce)
>   
>   		set_context_guc_id_invalid(cn);
>   
> +#ifdef CONFIG_DRM_I915_SELFTEST
> +		guc->number_guc_id_stole++;
> +#endif
> +
>   		return 0;
>   	} else {
>   		return -EAGAIN;
> @@ -3779,6 +3783,7 @@ static bool __guc_submission_selected(struct intel_guc *guc)
>   
>   void intel_guc_submission_init_early(struct intel_guc *guc)
>   {
> +	guc->submission_state.num_guc_ids = GUC_MAX_LRC_DESCRIPTORS;
>   	guc->submission_supported = __guc_submission_supported(guc);
>   	guc->submission_selected = __guc_submission_selected(guc);
>   }
> diff --git a/drivers/gpu/drm/i915/gt/uc/selftest_guc.c b/drivers/gpu/drm/i915/gt/uc/selftest_guc.c
> index fb0e4a7bd8ca..9ab355e64b3f 100644
> --- a/drivers/gpu/drm/i915/gt/uc/selftest_guc.c
> +++ b/drivers/gpu/drm/i915/gt/uc/selftest_guc.c
> @@ -3,8 +3,21 @@
>    * Copyright �� 2021 Intel Corporation
>    */
>   
> +#include "selftests/igt_spinner.h"
>   #include "selftests/intel_scheduler_helpers.h"
>   
> +static int request_add_spin(struct i915_request *rq, struct igt_spinner *spin)
> +{
> +	int err = 0;
> +
> +	i915_request_get(rq);
> +	i915_request_add(rq);
> +	if (spin && !igt_wait_for_spinner(spin, rq))
> +		err = -ETIMEDOUT;
> +
> +	return err;
> +}
> +
>   static struct i915_request *nop_user_request(struct intel_context *ce,
>   					     struct i915_request *from)
>   {
> @@ -110,10 +123,168 @@ static int intel_guc_scrub_ctbs(void *arg)
>   	return ret;
>   }
>   
> +/*
> + * intel_guc_steal_guc_ids - Test to exhaust all guc_ids and then steal one
> + *
> + * This test creates a spinner to which is used as to block all subsequent
to which -> which
as to block -> to block

> + * submissions until it completes. Next, a loop creates a context and a NOP
> + * request each iteration until the guc_ids are exhausted (request creation
> + * returns -EAGAIN). The spinner is completed unblocking all requests created in
spinner is ended,

> + * the loop. At this point all guc_ids are exhausted but are available to steal.
> + * Try to create another request which should successfully steal a guc_id. Wait
> + * on last request to complete, idle GPU, verify guc_id was stole via counter,
stole -> stolen

> + * and exit test. Test also artificially reduces the number of guc_ids so the
> + * test runs in a timely manner.
> + */
> +static int intel_guc_steal_guc_ids(void *arg)
> +{
> +	struct intel_gt *gt = arg;
> +	struct intel_guc *guc = &gt->uc.guc;
> +	int ret, sv, i = 0;
> +	intel_wakeref_t wakeref;
> +	struct intel_engine_cs *engine;
> +	struct intel_context **ce;
> +	struct igt_spinner spin;
> +	struct i915_request *spin_rq = NULL, *rq, *last = NULL;
> +	int number_guc_id_stole = guc->number_guc_id_stole;
stole -> stolen

> +
> +	ce = kzalloc(sizeof(*ce) * GUC_MAX_LRC_DESCRIPTORS, GFP_KERNEL);
> +	if (!ce) {
> +		pr_err("Context array allocation failed\n");
> +		return -ENOMEM;
> +	}
> +
> +	wakeref = intel_runtime_pm_get(gt->uncore->rpm);
> +	engine = intel_selftest_find_any_engine(gt);
> +	sv = guc->submission_state.num_guc_ids;
> +	guc->submission_state.num_guc_ids = 4096;
> +
> +	/* Create spinner to block requests in below loop */
> +	ce[i++] = intel_context_create(engine);
> +	if (IS_ERR(ce[i - 1])) {
> +		ce[i - 1] = NULL;
> +		ret = PTR_ERR(ce[i - 1]);
Would be less peculiar looking to do the i++ after the if statement.

> +		pr_err("Failed to create context: %d\n", ret);
> +		goto err_wakeref;
> +	}
> +	ret = igt_spinner_init(&spin, engine->gt);
> +	if (ret) {
> +		pr_err("Failed to create spinner: %d\n", ret);
> +		goto err_contexts;
> +	}
> +	spin_rq = igt_spinner_create_request(&spin, ce[i - 1], MI_ARB_CHECK);
> +	if (IS_ERR(spin_rq)) {
> +		ret = PTR_ERR(spin_rq);
> +		pr_err("Failed to create spinner request: %d\n", ret);
> +		goto err_contexts;
> +	}
> +	ret = request_add_spin(spin_rq, &spin);
> +	if (ret) {
> +		pr_err("Failed to add Spinner request: %d\n", ret);
> +		goto err_spin_rq;
> +	}
> +
> +	/* Use all guc_ids */
> +	while (ret != -EAGAIN) {
> +		ce[i++] = intel_context_create(engine);
> +		if (IS_ERR(ce[i - 1])) {
> +			ce[i - 1] = NULL;
> +			ret = PTR_ERR(ce[i - 1]);
> +			pr_err("Failed to create context: %d\n", ret);
> +			goto err_spin_rq;
Won't this try to put the null context? Or rather will see the null 
context and immediately abort the clean up loop. Need to do the i++ 
after the if statement. Or after the nop_user_request call to get rid of 
all the ce[i - 1] things.

John.

> +		}
> +
> +		rq = nop_user_request(ce[i - 1], spin_rq);
> +		if (IS_ERR(rq)) {
> +			ret = PTR_ERR(rq);
> +			rq = NULL;
> +			if (ret != -EAGAIN) {
> +				pr_err("Failed to create request, %d: %d\n", i,
> +				       ret);
> +				goto err_spin_rq;
> +			}
> +		} else {
> +			if (last)
> +				i915_request_put(last);
> +			last = rq;
> +		}
> +	}
> +
> +	/* Release blocked requests */
> +	igt_spinner_end(&spin);
> +	ret = intel_selftest_wait_for_rq(spin_rq);
> +	if (ret) {
> +		pr_err("Spin request failed to complete: %d\n", ret);
> +		i915_request_put(last);
> +		goto err_spin_rq;
> +	}
> +	i915_request_put(spin_rq);
> +	igt_spinner_fini(&spin);
> +	spin_rq = NULL;
> +
> +	/* Wait for last request */
> +	ret = i915_request_wait(last, 0, HZ * 30);
> +	i915_request_put(last);
> +	if (ret < 0) {
> +		pr_err("Last request failed to complete: %d\n", ret);
> +		goto err_spin_rq;
> +	}
> +
> +	/* Try to steal guc_id */
> +	rq = nop_user_request(ce[i - 1], NULL);
> +	if (IS_ERR(rq)) {
> +		ret = PTR_ERR(rq);
> +		pr_err("Failed to steal guc_id, %d: %d\n", i, ret);
> +		goto err_spin_rq;
> +	}
> +
> +	/* Wait for last request */
> +	ret = i915_request_wait(rq, 0, HZ);
> +	i915_request_put(rq);
> +	if (ret < 0) {
> +		pr_err("Last request failed to complete: %d\n", ret);
> +		goto err_spin_rq;
> +	}
> +
> +	/* Wait for idle */
> +	ret = intel_gt_wait_for_idle(gt, HZ * 30);
> +	if (ret < 0) {
> +		pr_err("GT failed to idle: %d\n", ret);
> +		goto err_spin_rq;
> +	}
> +
> +	/* Verify a guc_id got stole */
> +	if (guc->number_guc_id_stole == number_guc_id_stole) {
> +		pr_err("No guc_ids stolen");
> +		ret = -EINVAL;
> +	} else {
> +		ret = 0;
> +	}
> +
> +err_spin_rq:
> +	if (spin_rq) {
> +		igt_spinner_end(&spin);
> +		intel_selftest_wait_for_rq(spin_rq);
> +		i915_request_put(spin_rq);
> +		igt_spinner_fini(&spin);
> +		intel_gt_wait_for_idle(gt, HZ * 30);
> +	}
> +err_contexts:
> +	while (i && ce[--i])
> +		intel_context_put(ce[i]);
> +err_wakeref:
> +	intel_runtime_pm_put(gt->uncore->rpm, wakeref);
> +	kfree(ce);
> +	guc->submission_state.num_guc_ids = sv;
> +
> +	return ret;
> +}
> +
>   int intel_guc_live_selftests(struct drm_i915_private *i915)
>   {
>   	static const struct i915_subtest tests[] = {
>   		SUBTEST(intel_guc_scrub_ctbs),
> +		SUBTEST(intel_guc_steal_guc_ids),
>   	};
>   	struct intel_gt *gt = &i915->gt;
>   