Re: [PATCH v2] drm/sched: Add test suite for concurrent job submissions

Marco Pagani
2026-04-10T11:34:00Z

On 10/04/2026 11:19, Philipp Stanner wrote:
> On Fri, 2026-04-10 at 11:07 +0200, Marco Pagani wrote:
>>
>>
>> On 09/04/2026 17:35, Tvrtko Ursulin wrote:
>>>
>>> On 08/04/2026 16:49, Marco Pagani wrote:
>>>> Add a new test suite to simulate concurrent job submissions to the DRM
>>>> scheduler, as this functionality is not covered by current test suites.
>>>>
>>>> The new test suite includes two initial test cases: (i) a test case for
>>>> parallel job submission and (ii) a test case for interleaved job
>>>> submission and completion. In the first test case, worker threads
>>>> concurrently submit jobs to the scheduler, and then the timeline is
>>>> manually advanced to complete them in bulk. In the second test case,
>>>> worker threads concurrently submit sequences of jobs of different
>>>> durations to the mock scheduler using a sliding window to better model
>>>> real-world workloads. The timeline is advanced automatically by the
>>>> finishing jobs, interleaving submission with completion.
>>>>
>>>> Signed-off-by: Marco Pagani <marco.pagani@linux.dev>
>>>> ---
>>>> Changes in v2:
>>>> - Improved test description
>>>> - Use multiple job durations instead of harmonic periods/durations
>>>> - Improved submission for interleaved test with a sliding window
>>>> - Removed unnecessary asserts per Tvrtko's feedback, but kept wait_scheduled
>>>> - Changed parameter names from period to duration for clarity
>>>> - Used temp variables to reduce line breaks
>>>> ---
>>>>   drivers/gpu/drm/scheduler/tests/tests_basic.c | 356 ++++++++++++++++++
>>>>   1 file changed, 356 insertions(+)
>>>>
>>>> diff --git a/drivers/gpu/drm/scheduler/tests/tests_basic.c b/drivers/gpu/drm/scheduler/tests/tests_basic.c
>>>> index a5a5a35a87b0..1791b157cfc8 100644
>>>> --- a/drivers/gpu/drm/scheduler/tests/tests_basic.c
>>>> +++ b/drivers/gpu/drm/scheduler/tests/tests_basic.c
>>>> @@ -1,7 +1,11 @@
>>>>   // SPDX-License-Identifier: GPL-2.0
>>>>   /* Copyright (c) 2025 Valve Corporation */
>>>>
>>>> +#include <linux/completion.h>
>>>>   #include <linux/delay.h>
>>>> +#include <linux/minmax.h>
>>>> +#include <linux/time.h>
>>>> +#include <linux/workqueue.h>
>>>>
>>>>   #include "sched_tests.h"
>>>>
>>>> @@ -235,6 +239,357 @@ static void drm_sched_basic_cancel(struct kunit *test)
>>>>    KUNIT_ASSERT_EQ(test, job->hw_fence.error, -ECANCELED);
>>>>   }
>>>>
>>>> +struct sched_concurrent_context {
>>>> + struct drm_mock_scheduler *sched;
>>>> + struct workqueue_struct *sub_wq;
>>>> + struct kunit *test;
>>>> + struct completion wait_go;
>>>> +};
>>>> +
>>>> +KUNIT_DEFINE_ACTION_WRAPPER(drm_mock_sched_fini_wrap, drm_mock_sched_fini,
>>>> +     struct drm_mock_scheduler *);
>>>> +
>>>> +KUNIT_DEFINE_ACTION_WRAPPER(drm_mock_sched_entity_free_wrap, drm_mock_sched_entity_free,
>>>> +     struct drm_mock_sched_entity *);
>>>> +
>>>> +static void complete_destroy_workqueue(void *context)
>>>> +{
>>>> + struct sched_concurrent_context *ctx = context;
>>>> +
>>>> + complete_all(&ctx->wait_go);
>>>> +
>>>> + destroy_workqueue(ctx->sub_wq);
>>>> +}
>>>> +
>>>> +static int drm_sched_concurrent_init(struct kunit *test)
>>>> +{
>>>> + struct sched_concurrent_context *ctx;
>>>> + int ret;
>>>> +
>>>> + ctx = kunit_kzalloc(test, sizeof(*ctx), GFP_KERNEL);
>>>> + KUNIT_ASSERT_NOT_NULL(test, ctx);
>>>> +
>>>> + init_completion(&ctx->wait_go);
>>>> +
>>>> + ctx->sched = drm_mock_sched_new(test, MAX_SCHEDULE_TIMEOUT);
>>>> +
>>>> + ret = kunit_add_action_or_reset(test, drm_mock_sched_fini_wrap, ctx->sched);
>>>> + KUNIT_ASSERT_EQ(test, ret, 0);
>>>> +
>>>> + /* Use an unbounded workqueue to maximize job submission concurrency */
>>>> + ctx->sub_wq = alloc_workqueue("drm-sched-submitters-wq", WQ_UNBOUND,
>>>> +       WQ_UNBOUND_MAX_ACTIVE);
>>>> + KUNIT_ASSERT_NOT_NULL(test, ctx->sub_wq);
>>>> +
>>>> + ret = kunit_add_action_or_reset(test, complete_destroy_workqueue, ctx);
>>>> + KUNIT_ASSERT_EQ(test, ret, 0);
>>>> +
>>>> + ctx->test = test;
>>>> + test->priv = ctx;
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +struct drm_sched_parallel_params {
>>>> + const char *description;
>>>> + unsigned int num_jobs;
>>>> + unsigned int num_workers;
>>>> +};
>>>> +
>>>> +static const struct drm_sched_parallel_params drm_sched_parallel_cases[] = {
>>>> + {
>>>> + .description = "Parallel submission of multiple jobs per worker",
>>>> + .num_jobs = 8,
>>>> + .num_workers = 16,
>>>> + },
>>>> +};
>>>> +
>>>> +static void
>>>> +drm_sched_parallel_desc(const struct drm_sched_parallel_params *params, char *desc)
>>>> +{
>>>> + strscpy(desc, params->description, KUNIT_PARAM_DESC_SIZE);
>>>> +}
>>>> +
>>>> +KUNIT_ARRAY_PARAM(drm_sched_parallel, drm_sched_parallel_cases, drm_sched_parallel_desc);
>>>
>>> As long as you don't plan to add more test cases any time soon the
>>> boiler plate could be reduced by unot using KUNIT_ARRAY_PARAM but it is
>>> up to you. (Same for the other test below.)
>>
>> Right.
>>
>>>> +
>>>> +struct parallel_worker {
>>>> + struct work_struct work;
>>>> + struct sched_concurrent_context *ctx;
>>>> + struct drm_mock_sched_entity *entity;
>>>> + struct drm_mock_sched_job **jobs;
>>>> + unsigned int id;
>>>> +};
>>>> +
>>>> +static void drm_sched_parallel_worker(struct work_struct *work)
>>>> +{
>>>> + const struct drm_sched_parallel_params *params;
>>>> + struct sched_concurrent_context *test_ctx;
>>>> + struct parallel_worker *worker;
>>>> + unsigned int i;
>>>> +
>>>> + worker = container_of(work, struct parallel_worker, work);
>>>> + test_ctx = worker->ctx;
>>>> + params = test_ctx->test->param_value;
>>>> +
>>>> + wait_for_completion(&test_ctx->wait_go);
>>>> +
>>>> + kunit_info(test_ctx->test, "Parallel worker %u submitting %u jobs started\n",
>>>> +    worker->id, params->num_jobs);
>>>> +
>>>> + for (i = 0; i < params->num_jobs; i++)
>>>> + drm_mock_sched_job_submit(worker->jobs[i]);
>>>> +}
>>>> +
>>>> +/*
>>>> + * Spawns workers that submit a sequence of jobs to the mock scheduler.
>>>> + * Once all jobs are submitted, the timeline is manually advanced.
>>>> + */
>>>> +static void drm_sched_parallel_submit_test(struct kunit *test)
>>>> +{
>>>> + struct sched_concurrent_context *ctx = test->priv;
>>>> + const struct drm_sched_parallel_params *params = test->param_value;
>>>> + struct parallel_worker *workers, *worker;
>>>> + struct drm_mock_sched_job *job;
>>>> + unsigned int i, j, completed_jobs, total_jobs;
>>>> + bool done;
>>>> + int ret;
>>>> +
>>>> + KUNIT_ASSERT_GT(test, params->num_workers, 0);
>>>> + KUNIT_ASSERT_GT(test, params->num_jobs, 0);
>>>> +
>>>> + workers = kunit_kcalloc(test, params->num_workers, sizeof(*workers),
>>>> + GFP_KERNEL);
>>>> + KUNIT_ASSERT_NOT_NULL(test, workers);
>>>> +
>>>> + /*
>>>> + * Init workers only after all jobs and entities have been successfully
>>>> + * allocated. In this way, the cleanup logic for when an assertion fail
>>>> + * can be simplified.
>>>> + */
>>>> + for (i = 0; i < params->num_workers; i++) {
>>>> + worker = &workers[i];
>>>> + worker->id = i;
>>>> + worker->ctx = ctx;
>>>> + worker->entity = drm_mock_sched_entity_new(test,
>>>> +    DRM_SCHED_PRIORITY_NORMAL,
>>>> +    ctx->sched);
>>>> +
>>>> + ret = kunit_add_action_or_reset(test, drm_mock_sched_entity_free_wrap,
>>>> + worker->entity);
>>>> + KUNIT_ASSERT_EQ(test, ret, 0);
>>>> +
>>>> + worker->jobs = kunit_kcalloc(test, params->num_jobs,
>>>> +      sizeof(*worker->jobs), GFP_KERNEL);
>>>> + KUNIT_ASSERT_NOT_NULL(test, worker->jobs);
>>>> +
>>>> + for (j = 0; j < params->num_jobs; j++) {
>>>> + job = drm_mock_sched_job_new(test, worker->entity);
>>>> + worker->jobs[j] = job;
>>>> + }
>>>> + }
>>>> +
>>>> + for (i = 0; i < params->num_workers; i++) {
>>>> + worker = &workers[i];
>>>> + INIT_WORK(&worker->work, drm_sched_parallel_worker);
>>>> + queue_work(ctx->sub_wq, &worker->work);
>>>> + }
>>>> +
>>>> + complete_all(&ctx->wait_go);
>>>> + flush_workqueue(ctx->sub_wq);
>>>> +
>>>> + for (i = 0; i < params->num_workers; i++) {
>>>> + worker = &workers[i];
>>>> + for (j = 0; j < params->num_jobs; j++) {
>>>> + job = worker->jobs[j];
>>>> + done = drm_mock_sched_job_wait_scheduled(job, HZ);
>>>> + KUNIT_EXPECT_TRUE(test, done);
>>>> + }
>>>> + }
>>>> +
>>>> + total_jobs = params->num_workers * params->num_jobs;
>>>> + completed_jobs = drm_mock_sched_advance(ctx->sched, total_jobs);
>>>> + KUNIT_EXPECT_EQ(test, completed_jobs, total_jobs);
>>>> +
>>>> + for (i = 0; i < params->num_workers; i++) {
>>>> + worker = &workers[i];
>>>> + for (j = 0; j < params->num_jobs; j++) {
>>>> + job = worker->jobs[j];
>>>> + done = drm_mock_sched_job_wait_finished(job, HZ);
>>>> + KUNIT_EXPECT_TRUE(test, done);
>>>> + }
>>>> + }
>>>> +}
>>>> +
>>>> +struct drm_sched_interleaved_params {
>>>> + const char *description;
>>>> + unsigned int test_duration_ms;
>>>> + unsigned int job_base_duration_us;
>>>> + unsigned int num_workers;
>>>> + unsigned int num_in_flight_jobs;
>>>> +};
>>>> +
>>>> +static const struct drm_sched_interleaved_params drm_sched_interleaved_cases[] = {
>>>> + {
>>>> + .description = "Interleaved submission of multiple jobs per worker",
>>>> + .test_duration_ms = 1000,
>>>> + .job_base_duration_us = 100,
>>>> + .num_workers = 16,
>>>> + .num_in_flight_jobs = 8,
>>>> + },
>>>> +};
>>>> +
>>>> +static void
>>>> +drm_sched_interleaved_desc(const struct drm_sched_interleaved_params *params, char *desc)
>>>> +{
>>>> + strscpy(desc, params->description, KUNIT_PARAM_DESC_SIZE);
>>>> +}
>>>> +
>>>> +KUNIT_ARRAY_PARAM(drm_sched_interleaved, drm_sched_interleaved_cases,
>>>> +   drm_sched_interleaved_desc);
>>>> +
>>>> +struct interleaved_worker {
>>>> + struct work_struct work;
>>>> + struct sched_concurrent_context *ctx;
>>>> + struct drm_mock_sched_entity *entity;
>>>> + struct drm_mock_sched_job **jobs;
>>>> + unsigned int id;
>>>> + unsigned int job_count;
>>>> + unsigned int job_duration_us;
>>>> +};
>>>> +
>>>> +static void drm_sched_interleaved_worker(struct work_struct *work)
>>>> +{
>>>> + struct sched_concurrent_context *test_ctx;
>>>> + const struct drm_sched_interleaved_params *params;
>>>> + struct interleaved_worker *worker;
>>>> + unsigned int i, j, max_in_flight_job;
>>>> + unsigned long timeout;
>>>> + bool done;
>>>> +
>>>> + worker = container_of(work, struct interleaved_worker, work);
>>>> + test_ctx = worker->ctx;
>>>> + params = test_ctx->test->param_value;
>>>> +
>>>> + wait_for_completion(&test_ctx->wait_go);
>>>> +
>>>> + kunit_info(test_ctx->test, "Worker %u submitting %u jobs of %u us started\n",
>>>> +    worker->id, worker->job_count, worker->job_duration_us);
>>>> +
>>>> + timeout = msecs_to_jiffies(params->test_duration_ms * 2);
>>>> +
>>>> + /* Fill the submission window */
>>>> + max_in_flight_job = min(worker->job_count, params->num_in_flight_jobs);
>>>> + for (i = 0; i < max_in_flight_job; i++)
>>>> + drm_mock_sched_job_submit(worker->jobs[i]);
>>>> +
>>>> + /* Keep the window full by submitting a new job at once until done */
>>>> + for (i = 0; i < worker->job_count; i++) {
>>>> + done = drm_mock_sched_job_wait_finished(worker->jobs[i], timeout);
>>>> + if (!done)
>>>> + kunit_info(test_ctx->test, "Job %u of worker %u timed out\n",
>>>> +    i, worker->id);
>>>> +
>>>> + j = i + max_in_flight_job;
>>>> + if (j < worker->job_count)
>>>> + drm_mock_sched_job_submit(worker->jobs[j]);
>>>> + }
>>>
>>> The loop maybe isn't the most straight-forward but eventually looked to
>>> me like it will do what it wants.
>>
>> I will address this in my reply to your next message.
>>
>>> num_in_flight_jobs as a test parameter is perhaps arbitrary? I am not
>>> sure what it aims to achieve versus if workers would just be submitting
>>> one by one, or perhaps two by two, in both cases loops would be simpler.
>>
>> I think it's better to have it as a parameter rather than hardcoded in
>> the test.
>
> The tests are basically here to help us developers percuss the
> scheduler. So I would say we don't need to put thaaaat much focus on
> such details. Parameter sounds nice to me, but hardcoded wouldn't break
> any bones either.
>
>>
>>> Or even if num_in_flight_jobs would perhaps be automatically derived
>>> from the worker->id? If the goal is to simulate queue depth it sounds
>>> good to vary it.
>>
>> That's a nice idea, but I think having a fixed number of in_flight_jobs
>> expressed as a parameter is a good balance between test expressiveness
>> and simplicity.
>
> I think those are very detailed questions that one probably wants to
> address in a hypothetical "test payloads more realistically"-patch.
>
> This patch overall looks very good and tidy to me and I think we
> soonish want to take it as the "provide ground layer for concurrent job
> submission testing"-patch.
>
> So unless someone sees major blockers like bugs, I would like to take
> it in soonish, since it's been on-list for quite some time now and we
> seem to loose ourselves in deep-ish details :]
>
>>
>>> But these are minor points and up to you. The test now looks passably
>>> tidy as it is.
>>
>> Thanks for the tidy encouragement.
>>
>>> Ah wait, please also check if this one needs to be marked as "slow"
>>> kunit test. AFAIR all that are expected to take more than 1s need that.
>>
>> I've run it with UML and QEMU (arch=x86_64) and with the current parameters
>> kunit does not recommend to mark it as slow. But maybe you are right, it's
>> safer to mark it as slow anyway.
>
> +1
>
> If you can provide that in v3, it would seem we're good to go.

Sure, I'll address the comments and then prepare a v3.

Thanks,
Marco

>>>> +}
>>>> +
>>>> +/*
>>>> + * Spawns workers that submit a sequence of jobs to the mock scheduler. Job
>>>> + * durations are chosen as multiples of a base duration value specified as
>>>> + * a test parameter. Since the scheduler serializes jobs from all workers,
>>>> + * the total test duration budget is divided into equal shares among workers.
>>>> + * These shares are then used to compute the number of jobs that each worker
>>>> + * can submit
>>>> + */
>>>> +static void drm_sched_interleaved_submit_test(struct kunit *test)
>>>> +{
>>>> + const struct drm_sched_interleaved_params *params = test->param_value;
>>>> + struct sched_concurrent_context *ctx = test->priv;
>>>> + struct interleaved_worker *workers, *worker;
>>>> + struct drm_mock_sched_job *job;
>>>> + unsigned int worker_share_us;
>>>> + unsigned int i, j;
>>>> + bool done;
>>>> + int ret;
>>>> +
>>>> + KUNIT_ASSERT_GT(test, params->num_workers, 0);
>>>> + KUNIT_ASSERT_GT(test, params->job_base_duration_us, 0);
>>>> +
>>>> + workers = kunit_kcalloc(test, params->num_workers, sizeof(*workers),
>>>> + GFP_KERNEL);
>>>> + KUNIT_ASSERT_NOT_NULL(test, workers);
>>>> +
>>>> + /* Divide the available test time into equal shares among the workers */
>>>> + worker_share_us = (params->test_duration_ms * USEC_PER_MSEC) /
>>>> +   params->num_workers;
>>>> +
>>>> + /*
>>>> + * Init workers only after all jobs and entities have been successfully
>>>> + * allocated. In this way, the cleanup logic for when an assertion fails
>>>> + * can be simplified.
>>>> + */
>>>> + for (i = 0; i < params->num_workers; i++) {
>>>> + worker = &workers[i];
>>>> + worker->id = i;
>>>> + worker->ctx = ctx;
>>>> +
>>>> + worker->job_duration_us = params->job_base_duration_us * (i + 1);
>>>> + worker->job_count = worker_share_us / worker->job_duration_us;
>>>> + worker->job_count = max(1U, worker->job_count);
>>>> +
>>>> + worker->entity = drm_mock_sched_entity_new(test,
>>>> +    DRM_SCHED_PRIORITY_NORMAL,
>>>> +    ctx->sched);
>>>> +
>>>> + ret = kunit_add_action_or_reset(test, drm_mock_sched_entity_free_wrap,
>>>> + worker->entity);
>>>> + KUNIT_ASSERT_EQ(test, ret, 0);
>>>> +
>>>> + worker->jobs = kunit_kcalloc(test, worker->job_count,
>>>> +      sizeof(*worker->jobs), GFP_KERNEL);
>>>> + KUNIT_ASSERT_NOT_NULL(test, worker->jobs);
>>>> +
>>>> + for (j = 0; j < worker->job_count; j++) {
>>>> + job = drm_mock_sched_job_new(test, worker->entity);
>>>> + drm_mock_sched_job_set_duration_us(job, worker->job_duration_us);
>>>> +
>>>> + worker->jobs[j] = job;
>>>> + }
>>>> + }
>>>> +
>>>> + for (i = 0; i < params->num_workers; i++) {
>>>> + worker = &workers[i];
>>>> + INIT_WORK(&worker->work, drm_sched_interleaved_worker);
>>>> + queue_work(ctx->sub_wq, &worker->work);
>>>> + }
>>>> +
>>>> + complete_all(&ctx->wait_go);
>>>> + flush_workqueue(ctx->sub_wq);
>>>> +
>>>> + for (i = 0; i < params->num_workers; i++) {
>>>> + worker = &workers[i];
>>>> + for (j = 0; j < worker->job_count; j++) {
>>>> + job = worker->jobs[j];
>>>> + done = drm_mock_sched_job_is_finished(job);
>>>> + KUNIT_EXPECT_TRUE(test, done);
>>>> + }
>>>> + }
>>>> +}
>>>> +
>>>> +static struct kunit_case drm_sched_concurrent_tests[] = {
>>>> + KUNIT_CASE_PARAM(drm_sched_parallel_submit_test, drm_sched_parallel_gen_params),
>>>> + KUNIT_CASE_PARAM(drm_sched_interleaved_submit_test, drm_sched_interleaved_gen_params),
>>>> + {}
>>>> +};
>>>> +
>>>> +static struct kunit_suite drm_sched_concurrent = {
>>>> + .name = "drm_sched_concurrent_tests",
>>>> + .init = drm_sched_concurrent_init,
>>>> + .test_cases = drm_sched_concurrent_tests,
>>>> +};
>>>> +
>>>>   static struct kunit_case drm_sched_cancel_tests[] = {
>>>>    KUNIT_CASE(drm_sched_basic_cancel),
>>>>    {}
>>>> @@ -556,6 +911,7 @@ static struct kunit_suite drm_sched_credits = {
>>>>   };
>>>>
>>>>   kunit_test_suites(&drm_sched_basic,
>>>> +   &drm_sched_concurrent,
>>>>      &drm_sched_timeout,
>>>>      &drm_sched_cancel,
>>>>      &drm_sched_priority,
>>>
>>
>