drm/xe: Add stats for vma page faults

Add new entries in stats for vma page faults. If CONFIG_DEBUG_FS is
enabled, the count and number of bytes can be viewed per GT in the
stat debugfs file. This helps when testing, to confirm page faults
have been triggered as expected. It also helps when looking at the
performance impact of page faults. Data is simply collected when
entering the page fault handler so there is no indication whether
it completed successfully, with or without retries, etc.

Example output:

    cat /sys/kernel/debug/dri/0/gt0/stats
    tlb_inval_count: 129
    vma_pagefault_count: 12
    vma_pagefault_bytes: 98304

v2: Rebase

Reviewed-by: Jonathan Cavitt <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Signed-off-by: Francois Dugast <[email protected]>

Author: ifdu

drivers/gpu/drm/xe/xe_gt_pagefault.c

@@ -14,6 +14,7 @@
 #include "abi/guc_actions_abi.h"
 #include "xe_bo.h"
 #include "xe_gt.h"
+#include "xe_gt_stats.h"
 #include "xe_gt_tlb_invalidation.h"
 #include "xe_guc.h"
 #include "xe_guc_ct.h"
@@ -124,16 +125,20 @@ static int xe_pf_begin(struct drm_exec *exec, struct xe_vma *vma,
 	return 0;
 }
 
-static int handle_vma_pagefault(struct xe_tile *tile, struct pagefault *pf,
+static int handle_vma_pagefault(struct xe_gt *gt, struct pagefault *pf,
 				struct xe_vma *vma)
 {
 	struct xe_vm *vm = xe_vma_vm(vma);
+	struct xe_tile *tile = gt_to_tile(gt);
 	struct drm_exec exec;
 	struct dma_fence *fence;
 	ktime_t end = 0;
 	int err;
 	bool atomic;
 
+	xe_gt_stats_incr(gt, XE_GT_STATS_ID_VMA_PAGEFAULT_COUNT, 1);
+	xe_gt_stats_incr(gt, XE_GT_STATS_ID_VMA_PAGEFAULT_BYTES, xe_vma_size(vma));
+
 	trace_xe_vma_pagefault(vma);
 	atomic = access_is_atomic(pf->access_type);
 
@@ -202,7 +207,6 @@ static struct xe_vm *asid_to_vm(struct xe_device *xe, u32 asid)
 static int handle_pagefault(struct xe_gt *gt, struct pagefault *pf)
 {
 	struct xe_device *xe = gt_to_xe(gt);
-	struct xe_tile *tile = gt_to_tile(gt);
 	struct xe_vm *vm;
 	struct xe_vma *vma = NULL;
 	int err;
@@ -231,7 +235,7 @@ static int handle_pagefault(struct xe_gt *gt, struct pagefault *pf)
 		goto unlock_vm;
 	}
 
-	err = handle_vma_pagefault(tile, pf, vma);
+	err = handle_vma_pagefault(gt, pf, vma);
 
 unlock_vm:
 	if (!err)

drivers/gpu/drm/xe/xe_gt_stats.c

@@ -28,6 +28,8 @@ void xe_gt_stats_incr(struct xe_gt *gt, const enum xe_gt_stats_id id, int incr)
 
 static const char *const stat_description[__XE_GT_STATS_NUM_IDS] = {
 	"tlb_inval_count",
+	"vma_pagefault_count",
+	"vma_pagefault_bytes",
 };
 
 /**

drivers/gpu/drm/xe/xe_gt_stats_types.h

@@ -8,6 +8,8 @@
 
 enum xe_gt_stats_id {
 	XE_GT_STATS_ID_TLB_INVAL,
+	XE_GT_STATS_ID_VMA_PAGEFAULT_COUNT,
+	XE_GT_STATS_ID_VMA_PAGEFAULT_BYTES,
 	/* must be the last entry */
 	__XE_GT_STATS_NUM_IDS,
 };