Hi Vinay,
On 26-04-2025 03:21, Vinay Belgaumkar wrote:
As seen in some recent failures, SLPC num_waiters value is < 0.
This happens because the inc/dec are not balanced. We should skip
decrement for the same conditions as the increment. Currently, we
do that for power saving profile mode. This patch also ensures that
num_waiters is incremented in the case min_softlimit is at boost
freq. It ensures that we don't reduce the frequency while this request
is in flight.
Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/13598
Cc: Sk Anirban <sk.anir...@intel.com>
Signed-off-by: Vinay Belgaumkar <vinay.belgaum...@intel.com>
---
drivers/gpu/drm/i915/gt/intel_rps.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_rps.c
b/drivers/gpu/drm/i915/gt/intel_rps.c
index 8731f275fdd9..b609e3aa2122 100644
--- a/drivers/gpu/drm/i915/gt/intel_rps.c
+++ b/drivers/gpu/drm/i915/gt/intel_rps.c
@@ -1003,6 +1003,10 @@ void intel_rps_dec_waiters(struct intel_rps *rps)
if (rps_uses_slpc(rps)) {
slpc = rps_to_slpc(rps);
+ /* Don't decrement num_waiters for req where increment was skipped */
+ if (slpc->power_profile == SLPC_POWER_PROFILES_POWER_SAVING)
+ return;
+
intel_guc_slpc_dec_waiters(slpc);
} else {
atomic_dec(&rps->num_waiters);
@@ -1031,11 +1035,15 @@ void intel_rps_boost(struct i915_request *rq)
if (slpc->power_profile ==
SLPC_POWER_PROFILES_POWER_SAVING)
return;
- if (slpc->min_freq_softlimit >= slpc->boost_freq)
- return;
-
/* Return if old value is non zero */
if (!atomic_fetch_inc(&slpc->num_waiters)) {
+ /*
+ * Skip queuing boost work if frequency is
already boosted,
+ * but still increment num_waiters.
+ */
+ if (slpc->min_freq_softlimit >=
slpc->boost_freq)
+ return;
+
GT_TRACE(rps_to_gt(rps), "boost
fence:%llx:%llx\n",
rq->fence.context, rq->fence.seqno);
queue_work(rps_to_gt(rps)->i915->unordered_wq,
Tested on DG2, working as expected.
Reviewed-by: Sk Anirban <sk.anir...@intel.com>
