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Date: Sat, 24 Mar 2007 03:47:07 -0400
From: Adam Belay <abelay@...ell.com>
To: Len Brown <len.brown@...el.com>,
Thomas Gleixner <tglx@...utronix.de>
Cc: linux-kernel <linux-kernel@...r.kernel.org>,
Andrew Morton <akpm@...l.org>,
Shaohua Li <shaohua.li@...el.com>, Pallipadi@...r.kernel.org,
Venkatesh <venkatesh.pallipadi@...el.com>,
linux-acpi@...r.kernel.org
Subject: [RFC][PATCH 3/3] add the 'menu' cpuidle governor
This patch adds the 'menu' governor, as was described in my first email.
Thanks,
Adam
Kconfig | 11 +++
governors/Makefile | 1
governors/menu.c | 152 +++++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 164 insertions(+)
diff -urN a/drivers/cpuidle/governors/Makefile b/drivers/cpuidle/governors/Makefile
--- a/drivers/cpuidle/governors/Makefile 2007-03-23 23:09:45.000000000 -0400
+++ b/drivers/cpuidle/governors/Makefile 2007-03-24 02:10:29.000000000 -0400
@@ -3,3 +3,4 @@
#
obj-$(CONFIG_CPU_IDLE_GOV_LADDER) += ladder.o
+obj-$(CONFIG_CPU_IDLE_GOV_MENU) += menu.o
diff -urN a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
--- a/drivers/cpuidle/governors/menu.c 1969-12-31 19:00:00.000000000 -0500
+++ b/drivers/cpuidle/governors/menu.c 2007-03-23 23:51:15.000000000 -0400
@@ -0,0 +1,152 @@
+/*
+ * menu.c - the menu idle governor
+ *
+ * Copyright (C) 2006-2007 Adam Belay <abelay@...ell.com>
+ *
+ * This code is licenced under the GPL.
+ */
+
+#include <linux/kernel.h>
+#include <linux/cpuidle.h>
+#include <linux/latency.h>
+#include <linux/time.h>
+#include <linux/ktime.h>
+#include <linux/tick.h>
+#include <linux/hrtimer.h>
+
+#define BM_HOLDOFF 20000 /* 20 ms */
+
+struct menu_device {
+ int last_state_idx;
+ int deepest_bm_state;
+
+ int break_last_us;
+ int break_elapsed_us;
+
+ int bm_elapsed_us;
+ int bm_holdoff_us;
+
+ unsigned long idle_jiffies;
+};
+
+static DEFINE_PER_CPU(struct menu_device, menu_devices);
+
+/**
+ * menu_select - selects the next idle state to enter
+ * @dev: the CPU
+ */
+static int menu_select(struct cpuidle_device *dev)
+{
+ struct menu_device *data = &__get_cpu_var(menu_devices);
+ int i, expected_us, max_state = dev->state_count;
+
+ /* discard BM history because it is sticky */
+ cpuidle_get_bm_activity();
+
+ /* determine the expected residency time */
+ expected_us = (s32) ktime_to_ns(tick_nohz_get_sleep_length()) / 1000;
+ expected_us = min(expected_us, data->break_last_us);
+
+ /* determine the maximum state compatible with current BM status */
+ if (cpuidle_get_bm_activity())
+ data->bm_elapsed_us = 0;
+ if (data->bm_elapsed_us <= data->bm_holdoff_us)
+ max_state = data->deepest_bm_state + 1;
+
+ /* find the deepest idle state that satisfies our constraints */
+ for (i = 1; i < max_state; i++) {
+ struct cpuidle_state *s = &dev->states[i];
+ if (s->target_residency > expected_us)
+ break;
+ if (s->exit_latency > system_latency_constraint())
+ break;
+ }
+
+ data->last_state_idx = i - 1;
+ data->idle_jiffies = tick_nohz_get_idle_jiffies();
+ return i - 1;
+}
+
+/**
+ * menu_reflect - attempts to guess what happened after entry
+ * @dev: the CPU
+ *
+ * NOTE: it's important to be fast here because this operation will add to
+ * the overall exit latency.
+ */
+static void menu_reflect(struct cpuidle_device *dev)
+{
+ struct menu_device *data = &__get_cpu_var(menu_devices);
+ int last_idx = data->last_state_idx;
+ int measured_us = cpuidle_get_last_residency(dev);
+ struct cpuidle_state *target = &dev->states[last_idx];
+
+ /*
+ * Ugh, this idle state doesn't support residency measurements, so we
+ * are basically lost in the dark. As a compromise, assume we slept
+ * for one full standard timer tick. However, be aware that this
+ * could potentially result in a suboptimal state transition.
+ */
+ if (!(target->flags & CPUIDLE_FLAG_TIME_VALID))
+ measured_us = USEC_PER_SEC / HZ;
+
+ data->bm_elapsed_us += measured_us;
+ data->break_elapsed_us += measured_us;
+
+ /*
+ * Did something other than the timer interrupt cause the break event?
+ */
+ if (tick_nohz_get_idle_jiffies() == data->idle_jiffies) {
+ data->break_last_us = data->break_elapsed_us;
+ data->break_elapsed_us = 0;
+ }
+}
+
+/**
+ * menu_scan_device - scans a CPU's states and does setup
+ * @dev: the CPU
+ */
+static void menu_scan_device(struct cpuidle_device *dev)
+{
+ struct menu_device *data = &per_cpu(menu_devices, dev->cpu);
+ int i;
+
+ data->last_state_idx = 0;
+ data->break_last_us = 0;
+ data->break_elapsed_us = 0;
+ data->bm_elapsed_us = 0;
+ data->bm_holdoff_us = BM_HOLDOFF;
+
+ for (i = 1; i < dev->state_count; i++)
+ if (dev->states[i].flags & CPUIDLE_FLAG_CHECK_BM)
+ break;
+ data->deepest_bm_state = i - 1;
+}
+
+struct cpuidle_governor menu_governor = {
+ .name = "menu",
+ .scan = menu_scan_device,
+ .select = menu_select,
+ .reflect = menu_reflect,
+ .owner = THIS_MODULE,
+};
+
+/**
+ * init_menu - initializes the governor
+ */
+static int __init init_menu(void)
+{
+ return cpuidle_register_governor(&menu_governor);
+}
+
+/**
+ * exit_menu - exits the governor
+ */
+static void __exit exit_menu(void)
+{
+ cpuidle_unregister_governor(&menu_governor);
+}
+
+MODULE_LICENSE("GPL");
+module_init(init_menu);
+module_exit(exit_menu);
diff -urN a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
--- a/drivers/cpuidle/Kconfig 2007-03-23 23:09:45.000000000 -0400
+++ b/drivers/cpuidle/Kconfig 2007-03-24 02:18:19.000000000 -0400
@@ -23,6 +23,17 @@
states using residency time and bus master activity as metrics. This
algorithm was originally introduced in the old ACPI processor driver.
+config CPU_IDLE_GOV_MENU
+ tristate "'menu' governor"
+ depends on CPU_IDLE && NO_HZ
+ default y
+ help
+ This cpuidle governor evaluates all available states and chooses the
+ deepest state that meets all of the following constraints: BM activity,
+ expected time until next timer interrupt, and last break event time
+ delta. It is designed to minimize power consumption. Currently
+ dynticks is required.
+
endif # CPU_IDLE
endmenu
-
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