Re: [PATCH v2] drm/xe/ufence: Kick ufence immediately when possible

[Nirmoy Das <nirmoy.das@linux.intel.com>]

On 10/18/2024 1:53 AM, Matthew Brost wrote:
> On Thu, Oct 17, 2024 at 11:42:37AM +0200, Nirmoy Das wrote:
>> If the backing fence is signaled then signal ufence soon with
>> system_wq. This should reduce load from the xe ordered_wq and also
>> won't block signaling a ufence which doesn't require any serialization.
>>
>> v2: fix system_wq typo
>>
>> Link: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/1630
>> Cc: Matthew Auld <matthew.auld@intel.com>
>> gc: Matthew Brost <matthew.brost@intel.com>
>> Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
>> ---
>>  drivers/gpu/drm/xe/xe_sync.c | 12 ++++++++----
>>  1 file changed, 8 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/xe/xe_sync.c b/drivers/gpu/drm/xe/xe_sync.c
>> index c6cf227ead40..1a7907293088 100644
>> --- a/drivers/gpu/drm/xe/xe_sync.c
>> +++ b/drivers/gpu/drm/xe/xe_sync.c
>> @@ -89,10 +89,14 @@ static void user_fence_worker(struct work_struct *w)
>>  	user_fence_put(ufence);
>>  }
>>  
>> -static void kick_ufence(struct xe_user_fence *ufence, struct dma_fence *fence)
>> +static void kick_ufence(struct xe_user_fence *ufence, struct dma_fence *fence,
>> +			bool signaled)
> Predantic but maybe replace 'bool signaled' which a flag. We really want
> to avoid bools if possible.
>
> e.g.
>
> #define UFENCE_FLAG_SIGNALED	BIT(0)
>
> static void kick_ufence(struct xe_user_fence *ufence, struct dma_fence *fence,
> 			unsigned int flags)
> {
> 	...
> 	if (flags & UFENCE_FLAG_SIGNALED)
> 		...
> 	else
> 		...
> 	...	
> }
>
>>  {
>>  	INIT_WORK(&ufence->worker, user_fence_worker);
>> -	queue_work(ufence->xe->ordered_wq, &ufence->worker);
>> +	if (signaled)
>> +		queue_work(system_wq, &ufence->worker);
> I don't think you need the work queue here, just call the work func directly.


Ok, then I think we don't need flag either. Send a v3, let me know how that looks :)


Thanks,

Nirmoy

>
> s/queue_work(system_wq, &ufence->worker)/user_fence_worker(&ufence->worker)
>
> Matt
>
>> +	else
>> +		queue_work(ufence->xe->ordered_wq, &ufence->worker);
>>  	dma_fence_put(fence);
>>  }
>>  
>> @@ -100,7 +104,7 @@ static void user_fence_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
>>  {
>>  	struct xe_user_fence *ufence = container_of(cb, struct xe_user_fence, cb);
>>  
>> -	kick_ufence(ufence, fence);
>> +	kick_ufence(ufence, fence, false);
>>  }
>>  
>>  int xe_sync_entry_parse(struct xe_device *xe, struct xe_file *xef,
>> @@ -236,7 +240,7 @@ void xe_sync_entry_signal(struct xe_sync_entry *sync, struct dma_fence *fence)
>>  		err = dma_fence_add_callback(fence, &sync->ufence->cb,
>>  					     user_fence_cb);
>>  		if (err == -ENOENT) {
>> -			kick_ufence(sync->ufence, fence);
>> +			kick_ufence(sync->ufence, fence, true);
>>  		} else if (err) {
>>  			XE_WARN_ON("failed to add user fence");
>>  			user_fence_put(sync->ufence);
>> -- 
>> 2.46.0
>>