diff mbox series

drm/i915/guc/slpc: Use non-blocking H2G for waitboost

Message ID 20220623003225.23301-1-vinay.belgaumkar@intel.com (mailing list archive)
State New, archived
Headers show
Series drm/i915/guc/slpc: Use non-blocking H2G for waitboost | expand

Commit Message

Vinay Belgaumkar June 23, 2022, 12:32 a.m. UTC 
SLPC min/max frequency updates require H2G calls. We are seeing
timeouts when GuC channel is backed up and it is unable to respond
in a timely fashion causing warnings and affecting CI.

This is seen when waitboosting happens during a stress test.
this patch updates the waitboost path to use a non-blocking
H2G call instead, which returns as soon as the message is
successfully transmitted.

v2: Use drm_notice to report any errors that might occur while
sending the waitboost H2G request (Tvrtko)
v3: Add drm_notice inside force_min_freq (Ashutosh)

Cc: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
---
 drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c | 42 +++++++++++++++++----
 1 file changed, 35 insertions(+), 7 deletions(-)

Comments

Dixit, Ashutosh June 23, 2022, 12:53 a.m. UTC | #1 
On Wed, 22 Jun 2022 17:32:25 -0700, Vinay Belgaumkar wrote:
>
> @@ -208,12 +232,14 @@ static int slpc_force_min_freq(struct intel_guc_slpc *slpc, u32 freq)
>	 */
>
>	with_intel_runtime_pm(&i915->runtime_pm, wakeref) {
> -		ret = slpc_set_param(slpc,
> -				     SLPC_PARAM_GLOBAL_MIN_GT_UNSLICE_FREQ_MHZ,
> -				     freq);
> +		/* Non-blocking request will avoid stalls */
> +		ret = slpc_set_param_nb(slpc,
> +					SLPC_PARAM_GLOBAL_MIN_GT_UNSLICE_FREQ_MHZ,
> +					freq);
>		if (ret)
> -			i915_probe_error(i915, "Unable to force min freq to %u: %d",
> -					 freq, ret);
> +			drm_notice(&i915->drm,
> +				   "Failed to send set_param for min freq(%d): (%d)\n",
> +				   freq, ret);

I am still thinking if we should replace drm_notice() by i915_probe_error()
since drm_notice() will basically hide any issues of boost/de-boost's
getting dropped.

Another idea here might be to maintain a counter, say "slpc->failed_boosts"
which we increment each time slpc_set_param_nb() fails and dump that
counter via intel_guc_slpc_print_info().

Anyway for now this is:

Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
diff mbox series

Patch

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
index 2df31af70d63..ec9c4ca0f615 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
@@ -98,6 +98,30 @@  static u32 slpc_get_state(struct intel_guc_slpc *slpc)
 	return data->header.global_state;
 }
 
+static int guc_action_slpc_set_param_nb(struct intel_guc *guc, u8 id, u32 value)
+{
+	u32 request[] = {
+		GUC_ACTION_HOST2GUC_PC_SLPC_REQUEST,
+		SLPC_EVENT(SLPC_EVENT_PARAMETER_SET, 2),
+		id,
+		value,
+	};
+	int ret;
+
+	ret = intel_guc_send_nb(guc, request, ARRAY_SIZE(request), 0);
+
+	return ret > 0 ? -EPROTO : ret;
+}
+
+static int slpc_set_param_nb(struct intel_guc_slpc *slpc, u8 id, u32 value)
+{
+	struct intel_guc *guc = slpc_to_guc(slpc);
+
+	GEM_BUG_ON(id >= SLPC_MAX_PARAM);
+
+	return guc_action_slpc_set_param_nb(guc, id, value);
+}
+
 static int guc_action_slpc_set_param(struct intel_guc *guc, u8 id, u32 value)
 {
 	u32 request[] = {
@@ -208,12 +232,14 @@  static int slpc_force_min_freq(struct intel_guc_slpc *slpc, u32 freq)
 	 */
 
 	with_intel_runtime_pm(&i915->runtime_pm, wakeref) {
-		ret = slpc_set_param(slpc,
-				     SLPC_PARAM_GLOBAL_MIN_GT_UNSLICE_FREQ_MHZ,
-				     freq);
+		/* Non-blocking request will avoid stalls */
+		ret = slpc_set_param_nb(slpc,
+					SLPC_PARAM_GLOBAL_MIN_GT_UNSLICE_FREQ_MHZ,
+					freq);
 		if (ret)
-			i915_probe_error(i915, "Unable to force min freq to %u: %d",
-					 freq, ret);
+			drm_notice(&i915->drm,
+				   "Failed to send set_param for min freq(%d): (%d)\n",
+				   freq, ret);
 	}
 
 	return ret;
@@ -222,6 +248,7 @@  static int slpc_force_min_freq(struct intel_guc_slpc *slpc, u32 freq)
 static void slpc_boost_work(struct work_struct *work)
 {
 	struct intel_guc_slpc *slpc = container_of(work, typeof(*slpc), boost_work);
+	int err;
 
 	/*
 	 * Raise min freq to boost. It's possible that
@@ -231,8 +258,9 @@  static void slpc_boost_work(struct work_struct *work)
 	 */
 	mutex_lock(&slpc->lock);
 	if (atomic_read(&slpc->num_waiters)) {
-		slpc_force_min_freq(slpc, slpc->boost_freq);
-		slpc->num_boosts++;
+		err = slpc_force_min_freq(slpc, slpc->boost_freq);
+		if (!err)
+			slpc->num_boosts++;
 	}
 	mutex_unlock(&slpc->lock);
 }