This is a note to let you know that I've just added the patch titled
i915/guc: Ensure busyness counter increases motonically
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
i915-guc-ensure-busyness-counter-increases-motonical.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 97494a0f7a8117faf005baa5f5f4af9be7a2c516
Author: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@xxxxxxxxx>
Date: Wed Nov 27 09:40:05 2024 -0800
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 <umesh.nerlige.ramappa@xxxxxxxxx>
Reviewed-by: John Harrison <John.C.Harrison@xxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20241127174006.190128-3-umesh.nerlige.ramappa@xxxxxxxxx
(cherry picked from commit cf907f6d294217985e9dafd9985dce874e04ca37)
Signed-off-by: Tvrtko Ursulin <tursulin@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h
index a7e677598004..5a7e464b4fb3 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h
@@ -343,6 +343,11 @@ 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;
};
union intel_engine_tlb_inv_reg {
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 44610c739fe7..9028160b8448 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -1362,9 +1362,12 @@ 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 guc_enable_busyness_worker(struct intel_guc *guc)
