[PATCH 2/3] drm/xe/gt_stats: Use atomic64_t for counters

[Francois Dugast]

The stats counters are now used for things like counting the VMA
bytes during page faults. During workload execution, the counter
value can grow fast and easily reach the atomic int limit, in
which case it overflows. To make this less likely to happen, push
the limit by switching to 64b atomic to store the counter value.
Overhead is very small as there are only 3 stat entries per GT as
of now, and stats are only enabled with CONFIG_DEBUG_FS.

Suggested-by: Matthew Auld <matthew.auld at intel.com>
Signed-off-by: Francois Dugast <francois.dugast at intel.com>
---
 drivers/gpu/drm/xe/xe_gt_stats.c | 10 +++++-----
 drivers/gpu/drm/xe/xe_gt_types.h |  2 +-
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_gt_stats.c b/drivers/gpu/drm/xe/xe_gt_stats.c
index 753c081b68a6..83de2ec92fdc 100644
--- a/drivers/gpu/drm/xe/xe_gt_stats.c
+++ b/drivers/gpu/drm/xe/xe_gt_stats.c
@@ -30,11 +30,11 @@ void xe_gt_stats_incr(struct xe_gt *gt, const enum xe_gt_stats_id id, int incr)
 	if (id >= __XE_GT_STATS_NUM_IDS)
 		return;
 
-	atomic_add(incr, &gt->stats.counters[id]);
+	atomic64_add(incr, &gt->stats.counters[id]);
 
-	if (atomic_read(&gt->stats.counters[id]) < 0) {
+	if (atomic64_read(&gt->stats.counters[id]) < 0) {
 		xe_gt_dbg(gt, "stats %s overflow, resetting\n", stat_description[id]);
-		atomic_set(&gt->stats.counters[id], incr);
+		atomic64_set(&gt->stats.counters[id], incr);
 	}
 }
 
@@ -50,8 +50,8 @@ int xe_gt_stats_print_info(struct xe_gt *gt, struct drm_printer *p)
 	enum xe_gt_stats_id id;
 
 	for (id = 0; id < __XE_GT_STATS_NUM_IDS; ++id)
-		drm_printf(p, "%s: %d\n", stat_description[id],
-			   atomic_read(&gt->stats.counters[id]));
+		drm_printf(p, "%s: %lld\n", stat_description[id],
+			   atomic64_read(&gt->stats.counters[id]));
 
 	return 0;
 }
diff --git a/drivers/gpu/drm/xe/xe_gt_types.h b/drivers/gpu/drm/xe/xe_gt_types.h
index 6e66bf0e8b3f..f72b965cc9e6 100644
--- a/drivers/gpu/drm/xe/xe_gt_types.h
+++ b/drivers/gpu/drm/xe/xe_gt_types.h
@@ -139,7 +139,7 @@ struct xe_gt {
 	/** @stats: GT stats */
 	struct {
 		/** @stats.counters: counters for various GT stats */
-		atomic_t counters[__XE_GT_STATS_NUM_IDS];
+		atomic64_t counters[__XE_GT_STATS_NUM_IDS];
 	} stats;
 #endif
 
-- 
2.43.0