Re: [Intel-gfx] [PATCH 1/6] drm/i915: Individual request cancellation

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

On 22/03/2021 15:38, Matthew Auld wrote:
> On Thu, 18 Mar 2021 at 17:04, Tvrtko Ursulin
> <tvrtko.ursulin@linux.intel.com> wrote:
>>
>> From: Chris Wilson <chris@chris-wilson.co.uk>
>>
>> Currently, we cancel outstanding requests within a context when the
>> context is closed. We may also want to cancel individual requests using
>> the same graceful preemption mechanism.
>>
>> v2 (Tvrtko):
>>   * Cancel waiters carefully considering no timeline lock and RCU.
>>   * Fixed selftests.
>>
>> v3 (Tvrtko):
>>   * Remove error propagation to waiters for now.
>>
>> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>> ---
>>   .../gpu/drm/i915/gt/intel_engine_heartbeat.c  |   1 +
>>   .../drm/i915/gt/intel_execlists_submission.c  |   9 +-
>>   drivers/gpu/drm/i915/i915_request.c           |  52 ++++-
>>   drivers/gpu/drm/i915/i915_request.h           |   4 +-
>>   drivers/gpu/drm/i915/selftests/i915_request.c | 201 ++++++++++++++++++
>>   5 files changed, 261 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c b/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c
>> index 0b062fad1837..e2fb3ae2aaf3 100644
>> --- a/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c
>> +++ b/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c
>> @@ -314,6 +314,7 @@ int intel_engine_pulse(struct intel_engine_cs *engine)
>>                  mutex_unlock(&ce->timeline->mutex);
>>          }
>>
>> +       intel_engine_flush_scheduler(engine);
>>          intel_engine_pm_put(engine);
>>          return err;
>>   }
>> diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
>> index 85ff5fe861b4..4c2acb5a6c0a 100644
>> --- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
>> +++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
>> @@ -421,6 +421,11 @@ static void reset_active(struct i915_request *rq,
>>          ce->lrc.lrca = lrc_update_regs(ce, engine, head);
>>   }
>>
>> +static bool bad_request(const struct i915_request *rq)
>> +{
>> +       return rq->fence.error && i915_request_started(rq);
>> +}
>> +
>>   static struct intel_engine_cs *
>>   __execlists_schedule_in(struct i915_request *rq)
>>   {
>> @@ -433,7 +438,7 @@ __execlists_schedule_in(struct i915_request *rq)
>>                       !intel_engine_has_heartbeat(engine)))
>>                  intel_context_set_banned(ce);
>>
>> -       if (unlikely(intel_context_is_banned(ce)))
>> +       if (unlikely(intel_context_is_banned(ce) || bad_request(rq)))
>>                  reset_active(rq, engine);
>>
>>          if (IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM))
>> @@ -1112,7 +1117,7 @@ static unsigned long active_preempt_timeout(struct intel_engine_cs *engine,
>>                  return 0;
>>
>>          /* Force a fast reset for terminated contexts (ignoring sysfs!) */
>> -       if (unlikely(intel_context_is_banned(rq->context)))
>> +       if (unlikely(intel_context_is_banned(rq->context) || bad_request(rq)))
>>                  return 1;
>>
>>          return READ_ONCE(engine->props.preempt_timeout_ms);
>> diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
>> index e7b4c4bc41a6..b4511ac05e9a 100644
>> --- a/drivers/gpu/drm/i915/i915_request.c
>> +++ b/drivers/gpu/drm/i915/i915_request.c
>> @@ -33,7 +33,10 @@
>>   #include "gem/i915_gem_context.h"
>>   #include "gt/intel_breadcrumbs.h"
>>   #include "gt/intel_context.h"
>> +#include "gt/intel_engine.h"
>> +#include "gt/intel_engine_heartbeat.h"
>>   #include "gt/intel_gpu_commands.h"
>> +#include "gt/intel_reset.h"
>>   #include "gt/intel_ring.h"
>>   #include "gt/intel_rps.h"
>>
>> @@ -429,20 +432,22 @@ void __i915_request_skip(struct i915_request *rq)
>>          rq->infix = rq->postfix;
>>   }
>>
>> -void i915_request_set_error_once(struct i915_request *rq, int error)
>> +bool i915_request_set_error_once(struct i915_request *rq, int error)
>>   {
>>          int old;
>>
>>          GEM_BUG_ON(!IS_ERR_VALUE((long)error));
>>
>>          if (i915_request_signaled(rq))
>> -               return;
>> +               return false;
>>
>>          old = READ_ONCE(rq->fence.error);
>>          do {
>>                  if (fatal_error(old))
>> -                       return;
>> +                       return false;
>>          } while (!try_cmpxchg(&rq->fence.error, &old, error));
>> +
>> +       return true;
>>   }
>>
>>   struct i915_request *i915_request_mark_eio(struct i915_request *rq)
>> @@ -609,6 +614,47 @@ void i915_request_unsubmit(struct i915_request *request)
>>          spin_unlock_irqrestore(&se->lock, flags);
>>   }
>>
>> +static struct intel_engine_cs *active_engine(struct i915_request *rq)
>> +{
>> +       struct intel_engine_cs *engine, *locked;
>> +
>> +       locked = READ_ONCE(rq->engine);
>> +       spin_lock_irq(&locked->sched.lock);
>> +       while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
>> +               spin_unlock(&locked->sched.lock);
>> +               locked = engine;
>> +               spin_lock(&locked->sched.lock);
>> +       }
>> +
>> +       engine = NULL;
>> +       if (i915_request_is_active(rq) && !__i915_request_is_complete(rq))
>> +               engine = locked;
>> +
>> +       spin_unlock_irq(&locked->sched.lock);
>> +
>> +       return engine;
> 
> Bad idea to reuse __active_engine() somehow?

I can try and see how it ends up looking.

> Reviewed-by: Matthew Auld <matthew.auld@intel.com>
> 

Thanks,

Tvrtko
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