[PATCH v5 3/3] drm/i915: Predictive governor to control slice/subslice/eu

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High resolution timer is used for predictive governor to control
eu/slice/subslice based on workloads.

param is provided to enable/disable/update timer configuration

V2:
 * Fix code style.
 * Move predictive_load_timer into a drm_i915_private
   structure.
 * Make generic function to set optimum config. (Tvrtko Ursulin)

V3:
 * Rebase.
 * Fix race condition for predictive load set.
 * Add slack to start hrtimer for more power efficient. (Tvrtko Ursulin)

V4:
 * Fix data type and initialization of mutex to protect predictive load state.
 * Move predictive timer init to i915_gem_init_early. (Tvrtko Ursulin)
 * Move debugfs to kernel parameter.

V5:
 * Rebase.

Cc: Vipin Anand <vipin.anand@xxxxxxxxx>
Signed-off-by: Ankit Navik <ankit.p.navik@xxxxxxxxx>
---
 drivers/gpu/drm/i915/Makefile       |   1 +
 drivers/gpu/drm/i915/gt/intel_deu.c | 105 ++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/gt/intel_deu.h |   8 +++
 drivers/gpu/drm/i915/i915_drv.h     |   4 ++
 drivers/gpu/drm/i915/i915_gem.c     |   4 ++
 drivers/gpu/drm/i915/i915_params.c  |   4 ++
 drivers/gpu/drm/i915/i915_params.h  |   1 +
 7 files changed, 127 insertions(+)
 create mode 100644 drivers/gpu/drm/i915/gt/intel_deu.c
 create mode 100644 drivers/gpu/drm/i915/gt/intel_deu.h

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index e791d93..93e1ef0 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -77,6 +77,7 @@ obj-y += gt/
 gt-y += \
 	gt/intel_breadcrumbs.o \
 	gt/intel_context.o \
+	gt/intel_deu.o \
 	gt/intel_engine_cs.o \
 	gt/intel_engine_pool.o \
 	gt/intel_engine_pm.o \
diff --git a/drivers/gpu/drm/i915/gt/intel_deu.c b/drivers/gpu/drm/i915/gt/intel_deu.c
new file mode 100644
index 0000000..914c8ab
--- /dev/null
+++ b/drivers/gpu/drm/i915/gt/intel_deu.c
@@ -0,0 +1,105 @@
+/*
+ * Copyright © 2019 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Authors:
+ *    Ankit Navik <ankit.p.navik@xxxxxxxxx>
+ */
+
+/**
+ * DOC: Dynamic EU Control (DEU)
+ *
+ * DEU tries to re-configure EU allocation during runtime by predictive load
+ * calculation of command queue to gain power saving.
+ * It is transparent to user space and completely handled in the kernel.
+ */
+
+#include "intel_deu.h"
+#include "i915_drv.h"
+#include "gem/i915_gem_context.h"
+
+/*
+ * Anything above threshold is considered as HIGH load, less is considered
+ * as LOW load and equal is considered as MEDIUM load.
+ *
+ * The threshold value of three active requests pending.
+ */
+#define PENDING_THRESHOLD_MEDIUM 3
+
+#define SLACK_TIMER_NSEC 1000000 /* Timer range in nano second */
+
+enum hrtimer_restart predictive_load_cb(struct hrtimer *hrtimer)
+{
+	struct drm_i915_private *dev_priv =
+			container_of(hrtimer, typeof(*dev_priv), pred_timer);
+	struct i915_gem_context *ctx;
+	enum gem_load_type load_type;
+	unsigned int req_pending;
+
+	list_for_each_entry(ctx, &dev_priv->gem.contexts.list, link) {
+
+		req_pending = atomic_read(&ctx->req_cnt);
+
+		/*
+		 * Transitioning to low state whenever pending request is zero
+		 * would cause vacillation between low and high state.
+		 */
+		if (req_pending == 0)
+			continue;
+
+		if (req_pending > PENDING_THRESHOLD_MEDIUM)
+			load_type = LOAD_TYPE_HIGH;
+		else if (req_pending == PENDING_THRESHOLD_MEDIUM)
+			load_type = LOAD_TYPE_MEDIUM;
+		else
+			load_type = LOAD_TYPE_LOW;
+
+		i915_gem_context_set_load_type(ctx, load_type);
+	}
+
+	hrtimer_forward_now(hrtimer,
+			ms_to_ktime(dev_priv->predictive_load_enable));
+
+	return HRTIMER_RESTART;
+}
+
+/**
+ * intel_deu_init - Initialize dynamic EU
+ * @dev_priv: i915 device instance
+ *
+ * This fuction is called at driver load
+ */
+void intel_deu_init(struct drm_i915_private *dev_priv)
+{
+	dev_priv->predictive_load_enable = i915_modparams.deu_enable;
+	hrtimer_init(&dev_priv->pred_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	dev_priv->pred_timer.function = predictive_load_cb;
+
+	if (dev_priv->predictive_load_enable) {
+		if (!hrtimer_active(&dev_priv->pred_timer))
+			hrtimer_start_range_ns(&dev_priv->pred_timer,
+			ms_to_ktime(dev_priv->predictive_load_enable),
+			SLACK_TIMER_NSEC,
+			HRTIMER_MODE_REL_PINNED);
+	} else {
+		hrtimer_cancel(&dev_priv->pred_timer);
+	}
+}
diff --git a/drivers/gpu/drm/i915/gt/intel_deu.h b/drivers/gpu/drm/i915/gt/intel_deu.h
new file mode 100644
index 0000000..d55ede6
--- /dev/null
+++ b/drivers/gpu/drm/i915/gt/intel_deu.h
@@ -0,0 +1,8 @@
+#ifndef __INTEL_DEU_H__
+#define __INTEL_DEU_H__
+
+struct drm_i915_private;
+
+void intel_deu_init(struct drm_i915_private *dev_priv);
+
+#endif /* __INTEL_DEU_H__ */
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index ad8825f..66c4376 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1095,6 +1095,8 @@ struct drm_i915_private {
 	/* optimal slice/subslice/EU configration state */
 	struct i915_sseu_optimum_config *opt_config;
 
+	/* protects predictive load state */
+	struct hrtimer pred_timer;
 	int predictive_load_enable;
 
 	unsigned int fsb_freq, mem_freq, is_ddr3;
@@ -1850,6 +1852,8 @@ long i915_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);
 #endif
 extern const struct dev_pm_ops i915_pm_ops;
 
+extern enum hrtimer_restart predictive_load_cb(struct hrtimer *hrtimer);
+
 int i915_driver_probe(struct pci_dev *pdev, const struct pci_device_id *ent);
 void i915_driver_remove(struct drm_i915_private *i915);
 
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index dd0a327..159d1f56 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -45,6 +45,7 @@
 #include "gem/i915_gem_context.h"
 #include "gem/i915_gem_ioctls.h"
 #include "gem/i915_gem_pm.h"
+#include "gt/intel_deu.h"
 #include "gt/intel_engine_user.h"
 #include "gt/intel_gt.h"
 #include "gt/intel_gt_pm.h"
@@ -1435,6 +1436,9 @@ void i915_gem_init_early(struct drm_i915_private *dev_priv)
 	i915_gem_init__pm(dev_priv);
 
 	spin_lock_init(&dev_priv->fb_tracking.lock);
+
+	/* Dynamic EU timer initialization for predictive load */
+	intel_deu_init(dev_priv);
 }
 
 void i915_gem_cleanup_early(struct drm_i915_private *dev_priv)
diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index 4f1806f..6c63751 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -101,6 +101,10 @@ i915_param_named_unsafe(disable_power_well, int, 0400,
 
 i915_param_named_unsafe(enable_ips, int, 0600, "Enable IPS (default: true)");
 
+i915_param_named_unsafe(deu_enable, int, 0600,
+	"Enable dynamic EU control for power savings "
+	"(0=disable deu predictive timer [default], 150=optimal deu predictive timer)");
+
 i915_param_named(fastboot, int, 0600,
 	"Try to skip unnecessary mode sets at boot time "
 	"(0=disabled, 1=enabled) "
diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
index d29ade3..2d9584a 100644
--- a/drivers/gpu/drm/i915/i915_params.h
+++ b/drivers/gpu/drm/i915/i915_params.h
@@ -54,6 +54,7 @@ struct drm_printer;
 	param(int, disable_power_well, -1) \
 	param(int, enable_ips, 1) \
 	param(int, invert_brightness, 0) \
+	param(int, deu_enable, 0) \
 	param(int, enable_guc, 0) \
 	param(int, guc_log_level, -1) \
 	param(char *, guc_firmware_path, NULL) \
-- 
2.7.4

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