From: Umesh Nerlige Ramappa Date: Wed, 27 Nov 2024 17:40:05 +0000 (-0800) Subject: i915/guc: Ensure busyness counter increases motonically X-Git-Tag: v6.1.122~36 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7bfe589bbb5c1b9f6aa588675aa3b75023fa8eec;p=thirdparty%2Fkernel%2Fstable.git i915/guc: Ensure busyness counter increases motonically [ Upstream commit 59a0b46788d58fdcee8d2f6b4e619d264a1799bf ] Active busyness of an engine is calculated using gt timestamp and the context switch in time. While capturing the gt timestamp, it's possible that the context switches out. This race could result in an active busyness value that is greater than the actual context runtime value by a small amount. This leads to a negative delta and throws off busyness calculations for the user. If a subsequent count is smaller than the previous one, just return the previous one, since we expect the busyness to catch up. Fixes: 77cdd054dd2c ("drm/i915/pmu: Connect engine busyness stats from GuC to pmu") Signed-off-by: Umesh Nerlige Ramappa Reviewed-by: John Harrison Link: https://patchwork.freedesktop.org/patch/msgid/20241127174006.190128-3-umesh.nerlige.ramappa@intel.com (cherry picked from commit cf907f6d294217985e9dafd9985dce874e04ca37) Signed-off-by: Tvrtko Ursulin Signed-off-by: Sasha Levin --- diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h index 107f465a27b9e..458320d28e274 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h @@ -339,6 +339,11 @@ struct intel_engine_guc_stats { * @start_gt_clk: GT clock time of last idle to active transition. */ u64 start_gt_clk; + + /** + * @total: The last value of total returned + */ + u64 total; }; struct intel_engine_cs { diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c index 4bfc1131b4f00..2cd1f43f8a3c6 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c @@ -1346,9 +1346,12 @@ static ktime_t guc_engine_busyness(struct intel_engine_cs *engine, ktime_t *now) total += intel_gt_clock_interval_to_ns(gt, clk); } + if (total > stats->total) + stats->total = total; + spin_unlock_irqrestore(&guc->timestamp.lock, flags); - return ns_to_ktime(total); + return ns_to_ktime(stats->total); } static void __reset_guc_busyness_stats(struct intel_guc *guc)