Re: [PATCH 6/6] drm/xe: Add more GT stats around pagefault mode switch flows

[Francois Dugast <francois.dugast@intel.com>]

On Thu, Dec 11, 2025 at 01:00:32PM -0800, Matthew Brost wrote:
> Add GT stats to measure the time spent switching between pagefault mode
> and dma-fence mode. Also add a GT stat to indicate when pagefault
> suspend is skipped because the system is idle. These metrics will help
> profile pagefault workloads while 3D and display are enabled.
> 
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_gt_stats.c        |  6 +++++
>  drivers/gpu/drm/xe/xe_gt_stats_types.h  |  3 +++
>  drivers/gpu/drm/xe/xe_hw_engine_group.c | 32 +++++++++++++++++++++++++
>  3 files changed, 41 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_gt_stats.c b/drivers/gpu/drm/xe/xe_gt_stats.c
> index 714045ad9354..fb2904bd0abd 100644
> --- a/drivers/gpu/drm/xe/xe_gt_stats.c
> +++ b/drivers/gpu/drm/xe/xe_gt_stats.c
> @@ -68,8 +68,14 @@ static const char *const stat_description[__XE_GT_STATS_NUM_IDS] = {
>  	DEF_STAT_STR(SVM_2M_BIND_US, "svm_2M_bind_us"),
>  	DEF_STAT_STR(HW_ENGINE_GROUP_SUSPEND_LR_QUEUE_COUNT,
>  		     "hw_engine_group_suspend_lr_queue_count"),
> +	DEF_STAT_STR(HW_ENGINE_GROUP_SKIP_LR_QUEUE_COUNT,
> +		     "hw_engine_group_skip_lr_queue_count"),
>  	DEF_STAT_STR(HW_ENGINE_GROUP_WAIT_DMA_QUEUE_COUNT,
>  		     "hw_engine_group_wait_dma_queue_count"),
> +	DEF_STAT_STR(HW_ENGINE_GROUP_SUSPEND_LR_QUEUE_US,
> +		     "hw_engine_group_suspend_lr_queue_us"),
> +	DEF_STAT_STR(HW_ENGINE_GROUP_WAIT_DMA_QUEUE_US,
> +		     "hw_engine_group_wait_dma_queue_us"),
>  };
>  
>  /**
> diff --git a/drivers/gpu/drm/xe/xe_gt_stats_types.h b/drivers/gpu/drm/xe/xe_gt_stats_types.h
> index aada5df421e5..b92d013091d5 100644
> --- a/drivers/gpu/drm/xe/xe_gt_stats_types.h
> +++ b/drivers/gpu/drm/xe/xe_gt_stats_types.h
> @@ -45,7 +45,10 @@ enum xe_gt_stats_id {
>  	XE_GT_STATS_ID_SVM_64K_BIND_US,
>  	XE_GT_STATS_ID_SVM_2M_BIND_US,
>  	XE_GT_STATS_ID_HW_ENGINE_GROUP_SUSPEND_LR_QUEUE_COUNT,
> +	XE_GT_STATS_ID_HW_ENGINE_GROUP_SKIP_LR_QUEUE_COUNT,
>  	XE_GT_STATS_ID_HW_ENGINE_GROUP_WAIT_DMA_QUEUE_COUNT,
> +	XE_GT_STATS_ID_HW_ENGINE_GROUP_SUSPEND_LR_QUEUE_US,
> +	XE_GT_STATS_ID_HW_ENGINE_GROUP_WAIT_DMA_QUEUE_US,
>  	/* must be the last entry */
>  	__XE_GT_STATS_NUM_IDS,
>  };
> diff --git a/drivers/gpu/drm/xe/xe_hw_engine_group.c b/drivers/gpu/drm/xe/xe_hw_engine_group.c
> index 35966889c776..8236fdee0901 100644
> --- a/drivers/gpu/drm/xe/xe_hw_engine_group.c
> +++ b/drivers/gpu/drm/xe/xe_hw_engine_group.c
> @@ -14,6 +14,17 @@
>  #include "xe_sync.h"
>  #include "xe_vm.h"
>  
> +static s64 xe_hw_engine_group_stats_ktime_us_delta(ktime_t start)
> +{
> +	return IS_ENABLED(CONFIG_DEBUG_FS) ?
> +		ktime_us_delta(ktime_get(), start) : 0;
> +}
> +
> +static ktime_t xe_hw_engine_group_stats_ktime_get(void)
> +{
> +	return IS_ENABLED(CONFIG_DEBUG_FS) ? ktime_get() : 0;
> +}
> +

As they are not domain-specific, we could move xe_svm_stats_ktime_get()
and xe_svm_stats_ktime_us_delta() to xe_gt_stats.h and avoid duplication.

Francois

>  static void
>  hw_engine_group_resume_lr_jobs_func(struct work_struct *w)
>  {
> @@ -200,7 +211,9 @@ static int xe_hw_engine_group_suspend_faulting_lr_jobs(struct xe_hw_engine_group
>  {
>  	int err, i;
>  	struct xe_exec_queue *q;
> +	struct xe_gt *gt = NULL;
>  	bool need_resume = false;
> +	ktime_t start = xe_hw_engine_group_stats_ktime_get();
>  
>  	lockdep_assert_held_write(&group->mode_sem);
>  
> @@ -213,6 +226,9 @@ static int xe_hw_engine_group_suspend_faulting_lr_jobs(struct xe_hw_engine_group
>  		xe_gt_stats_incr(q->gt, XE_GT_STATS_ID_HW_ENGINE_GROUP_SUSPEND_LR_QUEUE_COUNT, 1);
>  
>  		idle_skip_suspend = xe_exec_queue_idle_skip_suspend(q);
> +		if (idle_skip_suspend)
> +			xe_gt_stats_incr(q->gt,
> +					 XE_GT_STATS_ID_HW_ENGINE_GROUP_SKIP_LR_QUEUE_COUNT, 1);
>  
>  		if (!need_resume && !idle_skip_suspend && num_syncs) {
>  			for (i = 0; i < num_syncs; ++i)
> @@ -221,6 +237,7 @@ static int xe_hw_engine_group_suspend_faulting_lr_jobs(struct xe_hw_engine_group
>  
>  		need_resume |= !idle_skip_suspend;
>  		q->ops->suspend(q);
> +		gt = q->gt;
>  	}
>  
>  	list_for_each_entry(q, &group->exec_queue_list, hw_engine_group_link) {
> @@ -232,6 +249,12 @@ static int xe_hw_engine_group_suspend_faulting_lr_jobs(struct xe_hw_engine_group
>  			return err;
>  	}
>  
> +	if (gt) {
> +		xe_gt_stats_incr(gt,
> +				 XE_GT_STATS_ID_HW_ENGINE_GROUP_SUSPEND_LR_QUEUE_US,
> +				 xe_hw_engine_group_stats_ktime_us_delta(start));
> +	}
> +
>  	if (need_resume)
>  		xe_hw_engine_group_resume_faulting_lr_jobs(group);
>  
> @@ -252,7 +275,9 @@ static int xe_hw_engine_group_wait_for_dma_fence_jobs(struct xe_hw_engine_group
>  {
>  	long timeout;
>  	struct xe_exec_queue *q;
> +	struct xe_gt *gt = NULL;
>  	struct dma_fence *fence;
> +	ktime_t start = xe_hw_engine_group_stats_ktime_get();
>  
>  	lockdep_assert_held_write(&group->mode_sem);
>  
> @@ -264,11 +289,18 @@ static int xe_hw_engine_group_wait_for_dma_fence_jobs(struct xe_hw_engine_group
>  		fence = xe_exec_queue_last_fence_get_for_resume(q, q->vm);
>  		timeout = dma_fence_wait(fence, false);
>  		dma_fence_put(fence);
> +		gt = q->gt;
>  
>  		if (timeout < 0)
>  			return -ETIME;
>  	}
>  
> +	if (gt) {
> +		xe_gt_stats_incr(gt,
> +				 XE_GT_STATS_ID_HW_ENGINE_GROUP_WAIT_DMA_QUEUE_US,
> +				 xe_hw_engine_group_stats_ktime_us_delta(start));
> +	}
> +
>  	return 0;
>  }
>  
> -- 
> 2.34.1
>