linux-kernel - [RFC PATCH v1 02/11] cpuidle: attach cpuidle governor statistics to the per-CPU device

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Date:   Mon, 10 Jul 2017 09:38:32 +0800
From:   Aubrey Li <aubrey.li@...el.com>
To:     tglx@...utronix.de, peterz@...radead.org, len.brown@...el.com,
        rjw@...ysocki.net, ak@...ux.intel.com, tim.c.chen@...ux.intel.com,
        arjan@...ux.intel.com, paulmck@...ux.vnet.ibm.com,
        yang.zhang.wz@...il.com
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Aubrey Li <aubrey.li@...ux.intel.com>
Subject: [RFC PATCH v1 02/11] cpuidle: attach cpuidle governor statistics to the per-CPU device

From: Aubrey Li <aubrey.li@...ux.intel.com>

A generic CPU idle governor is required to make the prediction of
how long the coming idle. The statistic data taken from the existing
menu governor is attached to the per-CPU device data structure
---
 include/linux/cpuidle.h | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index fc1e5d7..f17a53b 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -61,6 +61,34 @@ struct cpuidle_state {
 			      int index);
 };
 
+/*
+ * Please note when changing the tuning values:
+ * If (MAX_INTERESTING-1) * RESOLUTION > UINT_MAX, the result of
+ * a scaling operation multiplication may overflow on 32 bit platforms.
+ * In that case, #define RESOLUTION as ULL to get 64 bit result:
+ * #define RESOLUTION 1024ULL
+ *
+ * The default values do not overflow.
+ */
+#define	BUCKETS 12
+#define	INTERVAL_SHIFT 3
+#define	INTERVALS (1UL << INTERVAL_SHIFT)
+#define	RESOLUTION 1024
+#define	DECAY 8
+#define	MAX_INTERESTING 50000
+
+struct cpuidle_governor_stat {
+	int             last_state_idx;
+
+	unsigned int	next_timer_us;
+	unsigned int	predicted_us;
+	unsigned int	bucket;
+	unsigned int	correction_factor[BUCKETS];
+	unsigned int	intervals[INTERVALS];
+	int		interval_ptr;
+};
+
+
 /* Idle State Flags */
 #define CPUIDLE_FLAG_NONE       (0x00)
 #define CPUIDLE_FLAG_COUPLED	(0x02) /* state applies to multiple cpus */
@@ -89,8 +117,10 @@ struct cpuidle_device {
 	cpumask_t		coupled_cpus;
 	struct cpuidle_coupled	*coupled;
 #endif
+	struct cpuidle_governor_stat gov_stat;
 };
 
+
 DECLARE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
 DECLARE_PER_CPU(struct cpuidle_device, cpuidle_dev);
 
-- 
2.7.4