[Intel-xe] [PATCH v2 7/7] drm/xe/vm: Defer vm rebind until next exec if nothing to execute

[Matthew Brost]

On Wed, Mar 15, 2023 at 04:55:07PM +0100, Thomas Hellström wrote:
> If all compute engines of a vm in compute mode are idle,
> defer a rebind to the next exec to avoid the VM unnecessarily trying
> to make memory resident and compete with other VMs for available
> memory space.
> 
> v2:
> - Patch added to series.
> 
> Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>

Reviewed-by: Matthew Brost <matthew.brost at intel.com>

> ---
>  drivers/gpu/drm/xe/xe_exec.c     |  1 +
>  drivers/gpu/drm/xe/xe_vm.c       | 18 ++++++++++++++++++
>  drivers/gpu/drm/xe/xe_vm.h       | 17 +++++++++++++++++
>  drivers/gpu/drm/xe/xe_vm_types.h |  5 +++++
>  4 files changed, 41 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_exec.c b/drivers/gpu/drm/xe/xe_exec.c
> index 97fd1a311f2d..ea869f2452ef 100644
> --- a/drivers/gpu/drm/xe/xe_exec.c
> +++ b/drivers/gpu/drm/xe/xe_exec.c
> @@ -364,6 +364,7 @@ int xe_exec_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
>  				     &job->drm.s_fence->finished);
>  
>  	xe_sched_job_push(job);
> +	xe_vm_reactivate_rebind(vm);
>  
>  err_repin:
>  	if (!xe_vm_no_dma_fences(vm))
> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> index e8e178922082..6c466c628395 100644
> --- a/drivers/gpu/drm/xe/xe_vm.c
> +++ b/drivers/gpu/drm/xe/xe_vm.c
> @@ -226,6 +226,19 @@ static int wait_for_existing_preempt_fences(struct xe_vm *vm)
>  	return 0;
>  }
>  
> +static bool xe_vm_is_idle(struct xe_vm *vm)
> +{
> +	struct xe_engine *e;
> +
> +	xe_vm_assert_held(vm);
> +	list_for_each_entry(e, &vm->preempt.engines, compute.link) {
> +		if (!xe_engine_is_idle(e))
> +			return false;
> +	}
> +
> +	return true;
> +}
> +
>  static void arm_preempt_fences(struct xe_vm *vm, struct list_head *list)
>  {
>  	struct list_head *link;
> @@ -548,6 +561,11 @@ static void preempt_rebind_work_func(struct work_struct *w)
>  	if (err)
>  		goto out_unlock_outer;
>  
> +	if (xe_vm_is_idle(vm)) {
> +		vm->preempt.rebind_deactivated = true;
> +		goto out_unlock;
> +	}
> +			
>  	/* Fresh preempt fences already installed. Everyting is running. */
>  	if (!preempt_fences_waiting(vm))
>  		goto out_unlock;
> diff --git a/drivers/gpu/drm/xe/xe_vm.h b/drivers/gpu/drm/xe/xe_vm.h
> index 3468ed9d0528..748dc16ebed9 100644
> --- a/drivers/gpu/drm/xe/xe_vm.h
> +++ b/drivers/gpu/drm/xe/xe_vm.h
> @@ -98,6 +98,23 @@ extern struct ttm_device_funcs xe_ttm_funcs;
>  
>  struct ttm_buffer_object *xe_vm_ttm_bo(struct xe_vm *vm);
>  
> +/**
> + * xe_vm_reactivate_rebind() - Reactivate the rebind functionality on compute
> + * vms.
> + * @vm: The vm.
> + *
> + * If the rebind functionality on a compute vm was disabled due
> + * to nothing to execute. Reactivate it and run the rebind worker.
> + * This function should be called after submitting a batch to a compute vm.
> + */
> +static inline void xe_vm_reactivate_rebind(struct xe_vm *vm)
> +{
> +	if (xe_vm_in_compute_mode(vm) && vm->preempt.rebind_deactivated) {
> +		vm->preempt.rebind_deactivated = false;
> +		queue_work(system_unbound_wq, &vm->preempt.rebind_work);
> +	}
> +}
> +
>  static inline bool xe_vma_is_userptr(struct xe_vma *vma)
>  {
>  	return !vma->bo;
> diff --git a/drivers/gpu/drm/xe/xe_vm_types.h b/drivers/gpu/drm/xe/xe_vm_types.h
> index 2a3b911ab358..fada7896867f 100644
> --- a/drivers/gpu/drm/xe/xe_vm_types.h
> +++ b/drivers/gpu/drm/xe/xe_vm_types.h
> @@ -293,6 +293,11 @@ struct xe_vm {
>  		struct list_head engines;
>  		/** @num_engines: number user engines attached to this VM */
>  		int num_engines;
> +		/**
> +		 * @rebind_deactivated: Whether rebind has been temporarily deactivated
> +		 * due to no work available. Protected by the vm resv.
> +		 */
> +		bool rebind_deactivated;
>  		/**
>  		 * @rebind_work: worker to rebind invalidated userptrs / evicted
>  		 * BOs
> -- 
> 2.39.2
>