[PATCH] drm/i915/guc: Don't send policy update for child contexts.

[PATCH] drm/i915/guc: Don't send policy update for child contexts.

[Daniele Ceraolo Spurio]

The GuC FW applies the parent context policy to all the children,
so individual updates to the children are not supported and we
should not send them.

Note that sending the message did not have any functional consequences,
because the GuC just drops it and logs an error; since we were trying
to set the child policy to match the parent anyway the message being
dropped was not a problem.

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: John Harrison <john.c.harrison@intel.com>
---
 .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 26 +------------------
 1 file changed, 1 insertion(+), 25 deletions(-)

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 76916aed897a..5e31e2540297 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -2420,7 +2420,6 @@ static int guc_context_policy_init_v70(struct intel_context *ce, bool loop)
 	struct context_policy policy;
 	u32 execution_quantum;
 	u32 preemption_timeout;
-	bool missing = false;
 	unsigned long flags;
 	int ret;
 
@@ -2438,32 +2437,9 @@ static int guc_context_policy_init_v70(struct intel_context *ce, bool loop)
 		__guc_context_policy_add_preempt_to_idle(&policy, 1);
 
 	ret = __guc_context_set_context_policies(guc, &policy, loop);
-	missing = ret != 0;
-
-	if (!missing && intel_context_is_parent(ce)) {
-		struct intel_context *child;
-
-		for_each_child(ce, child) {
-			__guc_context_policy_start_klv(&policy, child->guc_id.id);
-
-			if (engine->flags & I915_ENGINE_WANT_FORCED_PREEMPTION)
-				__guc_context_policy_add_preempt_to_idle(&policy, 1);
-
-			child->guc_state.prio = ce->guc_state.prio;
-			__guc_context_policy_add_priority(&policy, ce->guc_state.prio);
-			__guc_context_policy_add_execution_quantum(&policy, execution_quantum);
-			__guc_context_policy_add_preemption_timeout(&policy, preemption_timeout);
-
-			ret = __guc_context_set_context_policies(guc, &policy, loop);
-			if (ret) {
-				missing = true;
-				break;
-			}
-		}
-	}
 
 	spin_lock_irqsave(&ce->guc_state.lock, flags);
-	if (missing)
+	if (ret != 0)
 		set_context_policy_required(ce);
 	else
 		clr_context_policy_required(ce);
-- 
2.25.1

Re: [PATCH] drm/i915/guc: Don't send policy update for child contexts.

[John Harrison]

On 7/27/2022 17:33, Daniele Ceraolo Spurio wrote:
> The GuC FW applies the parent context policy to all the children,
> so individual updates to the children are not supported and we
> should not send them.
>
> Note that sending the message did not have any functional consequences,
> because the GuC just drops it and logs an error; since we were trying
> to set the child policy to match the parent anyway the message being
> dropped was not a problem.
>
> Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
> Cc: John Harrison <john.c.harrison@intel.com>
Needs a Fixes tag for the original v70 update patch?

John.

> ---
>   .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 26 +------------------
>   1 file changed, 1 insertion(+), 25 deletions(-)
>
> 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 76916aed897a..5e31e2540297 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -2420,7 +2420,6 @@ static int guc_context_policy_init_v70(struct intel_context *ce, bool loop)
>   	struct context_policy policy;
>   	u32 execution_quantum;
>   	u32 preemption_timeout;
> -	bool missing = false;
>   	unsigned long flags;
>   	int ret;
>   
> @@ -2438,32 +2437,9 @@ static int guc_context_policy_init_v70(struct intel_context *ce, bool loop)
>   		__guc_context_policy_add_preempt_to_idle(&policy, 1);
>   
>   	ret = __guc_context_set_context_policies(guc, &policy, loop);
> -	missing = ret != 0;
> -
> -	if (!missing && intel_context_is_parent(ce)) {
> -		struct intel_context *child;
> -
> -		for_each_child(ce, child) {
> -			__guc_context_policy_start_klv(&policy, child->guc_id.id);
> -
> -			if (engine->flags & I915_ENGINE_WANT_FORCED_PREEMPTION)
> -				__guc_context_policy_add_preempt_to_idle(&policy, 1);
> -
> -			child->guc_state.prio = ce->guc_state.prio;
> -			__guc_context_policy_add_priority(&policy, ce->guc_state.prio);
> -			__guc_context_policy_add_execution_quantum(&policy, execution_quantum);
> -			__guc_context_policy_add_preemption_timeout(&policy, preemption_timeout);
> -
> -			ret = __guc_context_set_context_policies(guc, &policy, loop);
> -			if (ret) {
> -				missing = true;
> -				break;
> -			}
> -		}
> -	}
>   
>   	spin_lock_irqsave(&ce->guc_state.lock, flags);
> -	if (missing)
> +	if (ret != 0)
>   		set_context_policy_required(ce);
>   	else
>   		clr_context_policy_required(ce);

Re: [PATCH] drm/i915/guc: Don't send policy update for child contexts.

[Ceraolo Spurio, Daniele]

On 7/27/2022 6:44 PM, John Harrison wrote:
> On 7/27/2022 17:33, Daniele Ceraolo Spurio wrote:
>> The GuC FW applies the parent context policy to all the children,
>> so individual updates to the children are not supported and we
>> should not send them.
>>
>> Note that sending the message did not have any functional consequences,
>> because the GuC just drops it and logs an error; since we were trying
>> to set the child policy to match the parent anyway the message being
>> dropped was not a problem.
>>
>> Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
>> Cc: John Harrison <john.c.harrison@intel.com>
> Needs a Fixes tag for the original v70 update patch?

I don't think so. I added the explanation about it not being a 
functional issue to make it clear that everything still works as 
expected without this patch, just with a bit of extra noise in the GuC 
logs. If you think it is still worth applying to older kernels I'll add 
the tag in.

Daniele

>
> John.
>
>> ---
>>   .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 26 +------------------
>>   1 file changed, 1 insertion(+), 25 deletions(-)
>>
>> 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 76916aed897a..5e31e2540297 100644
>> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
>> @@ -2420,7 +2420,6 @@ static int guc_context_policy_init_v70(struct 
>> intel_context *ce, bool loop)
>>       struct context_policy policy;
>>       u32 execution_quantum;
>>       u32 preemption_timeout;
>> -    bool missing = false;
>>       unsigned long flags;
>>       int ret;
>>   @@ -2438,32 +2437,9 @@ static int 
>> guc_context_policy_init_v70(struct intel_context *ce, bool loop)
>>           __guc_context_policy_add_preempt_to_idle(&policy, 1);
>>         ret = __guc_context_set_context_policies(guc, &policy, loop);
>> -    missing = ret != 0;
>> -
>> -    if (!missing && intel_context_is_parent(ce)) {
>> -        struct intel_context *child;
>> -
>> -        for_each_child(ce, child) {
>> -            __guc_context_policy_start_klv(&policy, child->guc_id.id);
>> -
>> -            if (engine->flags & I915_ENGINE_WANT_FORCED_PREEMPTION)
>> - __guc_context_policy_add_preempt_to_idle(&policy, 1);
>> -
>> -            child->guc_state.prio = ce->guc_state.prio;
>> -            __guc_context_policy_add_priority(&policy, 
>> ce->guc_state.prio);
>> - __guc_context_policy_add_execution_quantum(&policy, 
>> execution_quantum);
>> - __guc_context_policy_add_preemption_timeout(&policy, 
>> preemption_timeout);
>> -
>> -            ret = __guc_context_set_context_policies(guc, &policy, 
>> loop);
>> -            if (ret) {
>> -                missing = true;
>> -                break;
>> -            }
>> -        }
>> -    }
>>         spin_lock_irqsave(&ce->guc_state.lock, flags);
>> -    if (missing)
>> +    if (ret != 0)
>>           set_context_policy_required(ce);
>>       else
>>           clr_context_policy_required(ce);
>

Re: [PATCH] drm/i915/guc: Don't send policy update for child contexts.

[John Harrison]

On 7/27/2022 18:50, Ceraolo Spurio, Daniele wrote:
> On 7/27/2022 6:44 PM, John Harrison wrote:
>> On 7/27/2022 17:33, Daniele Ceraolo Spurio wrote:
>>> The GuC FW applies the parent context policy to all the children,
>>> so individual updates to the children are not supported and we
>>> should not send them.
>>>
>>> Note that sending the message did not have any functional consequences,
>>> because the GuC just drops it and logs an error; since we were trying
>>> to set the child policy to match the parent anyway the message being
>>> dropped was not a problem.
>>>
>>> Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
>>> Cc: John Harrison <john.c.harrison@intel.com>
>> Needs a Fixes tag for the original v70 update patch?
>
> I don't think so. I added the explanation about it not being a 
> functional issue to make it clear that everything still works as 
> expected without this patch, just with a bit of extra noise in the GuC 
> logs. If you think it is still worth applying to older kernels I'll 
> add the tag in.
>
> Daniele
Hmm. It is strictly speaking a bug fix. But yes, the only impact is 
extra H2G traffic on context registration and in the GuC log. So maybe 
not worth worrying about.

Reviewed-by: John Harrison <John.C.Harrison@Intel.com>

>
>>
>> John.
>>
>>> ---
>>>   .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 26 
>>> +------------------
>>>   1 file changed, 1 insertion(+), 25 deletions(-)
>>>
>>> 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 76916aed897a..5e31e2540297 100644
>>> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
>>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
>>> @@ -2420,7 +2420,6 @@ static int guc_context_policy_init_v70(struct 
>>> intel_context *ce, bool loop)
>>>       struct context_policy policy;
>>>       u32 execution_quantum;
>>>       u32 preemption_timeout;
>>> -    bool missing = false;
>>>       unsigned long flags;
>>>       int ret;
>>>   @@ -2438,32 +2437,9 @@ static int 
>>> guc_context_policy_init_v70(struct intel_context *ce, bool loop)
>>> __guc_context_policy_add_preempt_to_idle(&policy, 1);
>>>         ret = __guc_context_set_context_policies(guc, &policy, loop);
>>> -    missing = ret != 0;
>>> -
>>> -    if (!missing && intel_context_is_parent(ce)) {
>>> -        struct intel_context *child;
>>> -
>>> -        for_each_child(ce, child) {
>>> -            __guc_context_policy_start_klv(&policy, child->guc_id.id);
>>> -
>>> -            if (engine->flags & I915_ENGINE_WANT_FORCED_PREEMPTION)
>>> - __guc_context_policy_add_preempt_to_idle(&policy, 1);
>>> -
>>> -            child->guc_state.prio = ce->guc_state.prio;
>>> -            __guc_context_policy_add_priority(&policy, 
>>> ce->guc_state.prio);
>>> - __guc_context_policy_add_execution_quantum(&policy, 
>>> execution_quantum);
>>> - __guc_context_policy_add_preemption_timeout(&policy, 
>>> preemption_timeout);
>>> -
>>> -            ret = __guc_context_set_context_policies(guc, &policy, 
>>> loop);
>>> -            if (ret) {
>>> -                missing = true;
>>> -                break;
>>> -            }
>>> -        }
>>> -    }
>>>         spin_lock_irqsave(&ce->guc_state.lock, flags);
>>> -    if (missing)
>>> +    if (ret != 0)
>>>           set_context_policy_required(ce);
>>>       else
>>>           clr_context_policy_required(ce);
>>
>