Commit | Line | Data |
---|---|---|
4f86d3a8 LB |
1 | /* |
2 | * ladder.c - the residency ladder algorithm | |
3 | * | |
4 | * Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com> | |
5 | * Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com> | |
6 | * Copyright (C) 2004, 2005 Dominik Brodowski <linux@brodo.de> | |
7 | * | |
8 | * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> | |
9 | * Shaohua Li <shaohua.li@intel.com> | |
10 | * Adam Belay <abelay@novell.com> | |
11 | * | |
12 | * This code is licenced under the GPL. | |
13 | */ | |
14 | ||
15 | #include <linux/kernel.h> | |
16 | #include <linux/cpuidle.h> | |
e8db0be1 | 17 | #include <linux/pm_qos.h> |
70e522a0 | 18 | #include <linux/module.h> |
4f86d3a8 LB |
19 | #include <linux/jiffies.h> |
20 | ||
21 | #include <asm/io.h> | |
22 | #include <asm/uaccess.h> | |
23 | ||
24 | #define PROMOTION_COUNT 4 | |
25 | #define DEMOTION_COUNT 1 | |
26 | ||
27 | struct ladder_device_state { | |
28 | struct { | |
29 | u32 promotion_count; | |
30 | u32 demotion_count; | |
31 | u32 promotion_time; | |
32 | u32 demotion_time; | |
33 | } threshold; | |
34 | struct { | |
35 | int promotion_count; | |
36 | int demotion_count; | |
37 | } stats; | |
38 | }; | |
39 | ||
40 | struct ladder_device { | |
41 | struct ladder_device_state states[CPUIDLE_STATE_MAX]; | |
42 | int last_state_idx; | |
43 | }; | |
44 | ||
45 | static DEFINE_PER_CPU(struct ladder_device, ladder_devices); | |
46 | ||
47 | /** | |
48 | * ladder_do_selection - prepares private data for a state change | |
49 | * @ldev: the ladder device | |
50 | * @old_idx: the current state index | |
51 | * @new_idx: the new target state index | |
52 | */ | |
53 | static inline void ladder_do_selection(struct ladder_device *ldev, | |
54 | int old_idx, int new_idx) | |
55 | { | |
56 | ldev->states[old_idx].stats.promotion_count = 0; | |
57 | ldev->states[old_idx].stats.demotion_count = 0; | |
58 | ldev->last_state_idx = new_idx; | |
59 | } | |
60 | ||
61 | /** | |
62 | * ladder_select_state - selects the next state to enter | |
46bcfad7 | 63 | * @drv: cpuidle driver |
4f86d3a8 LB |
64 | * @dev: the CPU |
65 | */ | |
46bcfad7 DD |
66 | static int ladder_select_state(struct cpuidle_driver *drv, |
67 | struct cpuidle_device *dev) | |
4f86d3a8 LB |
68 | { |
69 | struct ladder_device *ldev = &__get_cpu_var(ladder_devices); | |
70 | struct ladder_device_state *last_state; | |
71 | int last_residency, last_idx = ldev->last_state_idx; | |
ed77134b | 72 | int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY); |
4f86d3a8 | 73 | |
a2bd9202 | 74 | /* Special case when user has set very strict latency requirement */ |
75 | if (unlikely(latency_req == 0)) { | |
76 | ladder_do_selection(ldev, last_idx, 0); | |
77 | return 0; | |
78 | } | |
79 | ||
4f86d3a8 LB |
80 | last_state = &ldev->states[last_idx]; |
81 | ||
46bcfad7 DD |
82 | if (drv->states[last_idx].flags & CPUIDLE_FLAG_TIME_VALID) { |
83 | last_residency = cpuidle_get_last_residency(dev) - \ | |
84 | drv->states[last_idx].exit_latency; | |
85 | } | |
4f86d3a8 LB |
86 | else |
87 | last_residency = last_state->threshold.promotion_time + 1; | |
88 | ||
89 | /* consider promotion */ | |
46bcfad7 | 90 | if (last_idx < drv->state_count - 1 && |
62d6ae88 | 91 | !dev->states_usage[last_idx + 1].disable && |
4f86d3a8 | 92 | last_residency > last_state->threshold.promotion_time && |
46bcfad7 | 93 | drv->states[last_idx + 1].exit_latency <= latency_req) { |
4f86d3a8 LB |
94 | last_state->stats.promotion_count++; |
95 | last_state->stats.demotion_count = 0; | |
96 | if (last_state->stats.promotion_count >= last_state->threshold.promotion_count) { | |
97 | ladder_do_selection(ldev, last_idx, last_idx + 1); | |
98 | return last_idx + 1; | |
99 | } | |
100 | } | |
101 | ||
102 | /* consider demotion */ | |
06d9e908 | 103 | if (last_idx > CPUIDLE_DRIVER_STATE_START && |
62d6ae88 CE |
104 | (dev->states_usage[last_idx].disable || |
105 | drv->states[last_idx].exit_latency > latency_req)) { | |
06d9e908 | 106 | int i; |
107 | ||
108 | for (i = last_idx - 1; i > CPUIDLE_DRIVER_STATE_START; i--) { | |
46bcfad7 | 109 | if (drv->states[i].exit_latency <= latency_req) |
06d9e908 | 110 | break; |
111 | } | |
112 | ladder_do_selection(ldev, last_idx, i); | |
113 | return i; | |
114 | } | |
115 | ||
a2bd9202 | 116 | if (last_idx > CPUIDLE_DRIVER_STATE_START && |
4f86d3a8 LB |
117 | last_residency < last_state->threshold.demotion_time) { |
118 | last_state->stats.demotion_count++; | |
119 | last_state->stats.promotion_count = 0; | |
120 | if (last_state->stats.demotion_count >= last_state->threshold.demotion_count) { | |
121 | ladder_do_selection(ldev, last_idx, last_idx - 1); | |
122 | return last_idx - 1; | |
123 | } | |
124 | } | |
125 | ||
126 | /* otherwise remain at the current state */ | |
127 | return last_idx; | |
128 | } | |
129 | ||
130 | /** | |
131 | * ladder_enable_device - setup for the governor | |
46bcfad7 | 132 | * @drv: cpuidle driver |
4f86d3a8 LB |
133 | * @dev: the CPU |
134 | */ | |
46bcfad7 DD |
135 | static int ladder_enable_device(struct cpuidle_driver *drv, |
136 | struct cpuidle_device *dev) | |
4f86d3a8 LB |
137 | { |
138 | int i; | |
139 | struct ladder_device *ldev = &per_cpu(ladder_devices, dev->cpu); | |
140 | struct ladder_device_state *lstate; | |
141 | struct cpuidle_state *state; | |
142 | ||
a2bd9202 | 143 | ldev->last_state_idx = CPUIDLE_DRIVER_STATE_START; |
4f86d3a8 | 144 | |
46bcfad7 DD |
145 | for (i = 0; i < drv->state_count; i++) { |
146 | state = &drv->states[i]; | |
4f86d3a8 LB |
147 | lstate = &ldev->states[i]; |
148 | ||
149 | lstate->stats.promotion_count = 0; | |
150 | lstate->stats.demotion_count = 0; | |
151 | ||
152 | lstate->threshold.promotion_count = PROMOTION_COUNT; | |
153 | lstate->threshold.demotion_count = DEMOTION_COUNT; | |
154 | ||
46bcfad7 | 155 | if (i < drv->state_count - 1) |
4f86d3a8 LB |
156 | lstate->threshold.promotion_time = state->exit_latency; |
157 | if (i > 0) | |
158 | lstate->threshold.demotion_time = state->exit_latency; | |
159 | } | |
160 | ||
161 | return 0; | |
162 | } | |
163 | ||
e978aa7d DD |
164 | /** |
165 | * ladder_reflect - update the correct last_state_idx | |
166 | * @dev: the CPU | |
167 | * @index: the index of actual state entered | |
168 | */ | |
169 | static void ladder_reflect(struct cpuidle_device *dev, int index) | |
170 | { | |
171 | struct ladder_device *ldev = &__get_cpu_var(ladder_devices); | |
172 | if (index > 0) | |
173 | ldev->last_state_idx = index; | |
174 | } | |
175 | ||
4f86d3a8 LB |
176 | static struct cpuidle_governor ladder_governor = { |
177 | .name = "ladder", | |
178 | .rating = 10, | |
179 | .enable = ladder_enable_device, | |
180 | .select = ladder_select_state, | |
e978aa7d | 181 | .reflect = ladder_reflect, |
4f86d3a8 LB |
182 | .owner = THIS_MODULE, |
183 | }; | |
184 | ||
185 | /** | |
186 | * init_ladder - initializes the governor | |
187 | */ | |
188 | static int __init init_ladder(void) | |
189 | { | |
190 | return cpuidle_register_governor(&ladder_governor); | |
191 | } | |
192 | ||
193 | /** | |
194 | * exit_ladder - exits the governor | |
195 | */ | |
196 | static void __exit exit_ladder(void) | |
197 | { | |
198 | cpuidle_unregister_governor(&ladder_governor); | |
199 | } | |
200 | ||
201 | MODULE_LICENSE("GPL"); | |
202 | module_init(init_ladder); | |
203 | module_exit(exit_ladder); |