From: Francois Dugast <francois.dugast@intel.com>
Date: Tue, 25 Feb 2025 19:57:33 +0000 (+0100)
Subject: drm/xe/gt_stats: Use atomic64_t for counters
X-Git-Tag: v6.15-rc1~120^2~10^2~73
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=4f109b061c12d63b332338ce9192593842fa09a4;p=thirdparty%2Fkernel%2Flinux.git

drm/xe/gt_stats: Use atomic64_t for counters

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@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250225195902.1247100-2-francois.dugast@intel.com
Signed-off-by: Francois Dugast <francois.dugast@intel.com>
---

diff --git a/drivers/gpu/drm/xe/xe_gt_stats.c b/drivers/gpu/drm/xe/xe_gt_stats.c
index 2e9879ea4674a..af3fd03f665c5 100644
--- a/drivers/gpu/drm/xe/xe_gt_stats.c
+++ b/drivers/gpu/drm/xe/xe_gt_stats.c
@@ -23,7 +23,7 @@ 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]);
 }
 
 static const char *const stat_description[__XE_GT_STATS_NUM_IDS] = {
@@ -44,8 +44,8 @@ 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 6e66bf0e8b3f7..f72b965cc9e66 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