[PATCH 18/24] drm/amdkfd: enable pc sampling start

[Felix Kuehling]

On 2023-11-03 09:11, James Zhu wrote:
> Enable pc sampling start.
>
> Signed-off-by: James Zhu <James.Zhu at amd.com>
> ---
>   drivers/gpu/drm/amd/amdkfd/kfd_pc_sampling.c | 26 +++++++++++++++++---
>   drivers/gpu/drm/amd/amdkfd/kfd_priv.h        |  2 ++
>   2 files changed, 25 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_pc_sampling.c b/drivers/gpu/drm/amd/amdkfd/kfd_pc_sampling.c
> index 60b29b245db5..33d003ca0093 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_pc_sampling.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_pc_sampling.c
> @@ -83,9 +83,29 @@ static int kfd_pc_sample_query_cap(struct kfd_process_device *pdd,
>   	return 0;
>   }
>   
> -static int kfd_pc_sample_start(struct kfd_process_device *pdd)
> +static int kfd_pc_sample_start(struct kfd_process_device *pdd,
> +					struct pc_sampling_entry *pcs_entry)
>   {
> -	return -EINVAL;
> +	bool pc_sampling_start = false;
> +
> +	pcs_entry->enabled = true;
> +	mutex_lock(&pdd->dev->pcs_data.mutex);
> +	if (!pdd->dev->pcs_data.hosttrap_entry.base.active_count)
> +		pc_sampling_start = true;
> +	pdd->dev->pcs_data.hosttrap_entry.base.active_count++;
> +	mutex_unlock(&pdd->dev->pcs_data.mutex);
> +
> +	while (pc_sampling_start) {
> +		if (READ_ONCE(pdd->dev->pcs_data.hosttrap_entry.base.stop_enable)) {
> +			usleep_range(1000, 2000);

I don't understand why you need this synchronization through 
stop_enable. Why can't you do both the start and stop while holding the 
mutex? It's just setting a flag in the TMA, so it's not a time-consuming 
operation, and I don't see any potential for deadlocks.

Regards,
   Felix


> +		} else {
> +			kfd_process_set_trap_pc_sampling_flag(&pdd->qpd,
> +				pdd->dev->pcs_data.hosttrap_entry.base.pc_sample_info.method, true);
> +			break;
> +		}
> +	}
> +
> +	return 0;
>   }
>   
>   static int kfd_pc_sample_stop(struct kfd_process_device *pdd)
> @@ -225,7 +245,7 @@ int kfd_pc_sample(struct kfd_process_device *pdd,
>   		if (pcs_entry->enabled)
>   			return -EALREADY;
>   		else
> -			return kfd_pc_sample_start(pdd);
> +			return kfd_pc_sample_start(pdd, pcs_entry);
>   
>   	case KFD_IOCTL_PCS_OP_STOP:
>   		if (!pcs_entry->enabled)
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> index 6670534f47b8..613910e0d440 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> @@ -258,6 +258,8 @@ struct kfd_dev;
>   
>   struct kfd_dev_pc_sampling_data {
>   	uint32_t use_count;         /* Num of PC sampling sessions */
> +	uint32_t active_count;      /* Num of active sessions */
> +	bool stop_enable;           /* pc sampling stop in process */
>   	struct idr pc_sampling_idr;
>   	struct kfd_pc_sample_info pc_sample_info;
>   };