Root/
1 | /* |
2 | * Fast batching percpu counters. |
3 | */ |
4 | |
5 | #include <linux/percpu_counter.h> |
6 | #include <linux/notifier.h> |
7 | #include <linux/mutex.h> |
8 | #include <linux/init.h> |
9 | #include <linux/cpu.h> |
10 | #include <linux/module.h> |
11 | #include <linux/debugobjects.h> |
12 | |
13 | #ifdef CONFIG_HOTPLUG_CPU |
14 | static LIST_HEAD(percpu_counters); |
15 | static DEFINE_SPINLOCK(percpu_counters_lock); |
16 | #endif |
17 | |
18 | #ifdef CONFIG_DEBUG_OBJECTS_PERCPU_COUNTER |
19 | |
20 | static struct debug_obj_descr percpu_counter_debug_descr; |
21 | |
22 | static int percpu_counter_fixup_free(void *addr, enum debug_obj_state state) |
23 | { |
24 | struct percpu_counter *fbc = addr; |
25 | |
26 | switch (state) { |
27 | case ODEBUG_STATE_ACTIVE: |
28 | percpu_counter_destroy(fbc); |
29 | debug_object_free(fbc, &percpu_counter_debug_descr); |
30 | return 1; |
31 | default: |
32 | return 0; |
33 | } |
34 | } |
35 | |
36 | static struct debug_obj_descr percpu_counter_debug_descr = { |
37 | .name = "percpu_counter", |
38 | .fixup_free = percpu_counter_fixup_free, |
39 | }; |
40 | |
41 | static inline void debug_percpu_counter_activate(struct percpu_counter *fbc) |
42 | { |
43 | debug_object_init(fbc, &percpu_counter_debug_descr); |
44 | debug_object_activate(fbc, &percpu_counter_debug_descr); |
45 | } |
46 | |
47 | static inline void debug_percpu_counter_deactivate(struct percpu_counter *fbc) |
48 | { |
49 | debug_object_deactivate(fbc, &percpu_counter_debug_descr); |
50 | debug_object_free(fbc, &percpu_counter_debug_descr); |
51 | } |
52 | |
53 | #else /* CONFIG_DEBUG_OBJECTS_PERCPU_COUNTER */ |
54 | static inline void debug_percpu_counter_activate(struct percpu_counter *fbc) |
55 | { } |
56 | static inline void debug_percpu_counter_deactivate(struct percpu_counter *fbc) |
57 | { } |
58 | #endif /* CONFIG_DEBUG_OBJECTS_PERCPU_COUNTER */ |
59 | |
60 | void percpu_counter_set(struct percpu_counter *fbc, s64 amount) |
61 | { |
62 | int cpu; |
63 | unsigned long flags; |
64 | |
65 | raw_spin_lock_irqsave(&fbc->lock, flags); |
66 | for_each_possible_cpu(cpu) { |
67 | s32 *pcount = per_cpu_ptr(fbc->counters, cpu); |
68 | *pcount = 0; |
69 | } |
70 | fbc->count = amount; |
71 | raw_spin_unlock_irqrestore(&fbc->lock, flags); |
72 | } |
73 | EXPORT_SYMBOL(percpu_counter_set); |
74 | |
75 | void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch) |
76 | { |
77 | s64 count; |
78 | |
79 | preempt_disable(); |
80 | count = __this_cpu_read(*fbc->counters) + amount; |
81 | if (count >= batch || count <= -batch) { |
82 | unsigned long flags; |
83 | raw_spin_lock_irqsave(&fbc->lock, flags); |
84 | fbc->count += count; |
85 | __this_cpu_sub(*fbc->counters, count - amount); |
86 | raw_spin_unlock_irqrestore(&fbc->lock, flags); |
87 | } else { |
88 | this_cpu_add(*fbc->counters, amount); |
89 | } |
90 | preempt_enable(); |
91 | } |
92 | EXPORT_SYMBOL(__percpu_counter_add); |
93 | |
94 | /* |
95 | * Add up all the per-cpu counts, return the result. This is a more accurate |
96 | * but much slower version of percpu_counter_read_positive() |
97 | */ |
98 | s64 __percpu_counter_sum(struct percpu_counter *fbc) |
99 | { |
100 | s64 ret; |
101 | int cpu; |
102 | unsigned long flags; |
103 | |
104 | raw_spin_lock_irqsave(&fbc->lock, flags); |
105 | ret = fbc->count; |
106 | for_each_online_cpu(cpu) { |
107 | s32 *pcount = per_cpu_ptr(fbc->counters, cpu); |
108 | ret += *pcount; |
109 | } |
110 | raw_spin_unlock_irqrestore(&fbc->lock, flags); |
111 | return ret; |
112 | } |
113 | EXPORT_SYMBOL(__percpu_counter_sum); |
114 | |
115 | int __percpu_counter_init(struct percpu_counter *fbc, s64 amount, |
116 | struct lock_class_key *key) |
117 | { |
118 | raw_spin_lock_init(&fbc->lock); |
119 | lockdep_set_class(&fbc->lock, key); |
120 | fbc->count = amount; |
121 | fbc->counters = alloc_percpu(s32); |
122 | if (!fbc->counters) |
123 | return -ENOMEM; |
124 | |
125 | debug_percpu_counter_activate(fbc); |
126 | |
127 | #ifdef CONFIG_HOTPLUG_CPU |
128 | INIT_LIST_HEAD(&fbc->list); |
129 | spin_lock(&percpu_counters_lock); |
130 | list_add(&fbc->list, &percpu_counters); |
131 | spin_unlock(&percpu_counters_lock); |
132 | #endif |
133 | return 0; |
134 | } |
135 | EXPORT_SYMBOL(__percpu_counter_init); |
136 | |
137 | void percpu_counter_destroy(struct percpu_counter *fbc) |
138 | { |
139 | if (!fbc->counters) |
140 | return; |
141 | |
142 | debug_percpu_counter_deactivate(fbc); |
143 | |
144 | #ifdef CONFIG_HOTPLUG_CPU |
145 | spin_lock(&percpu_counters_lock); |
146 | list_del(&fbc->list); |
147 | spin_unlock(&percpu_counters_lock); |
148 | #endif |
149 | free_percpu(fbc->counters); |
150 | fbc->counters = NULL; |
151 | } |
152 | EXPORT_SYMBOL(percpu_counter_destroy); |
153 | |
154 | int percpu_counter_batch __read_mostly = 32; |
155 | EXPORT_SYMBOL(percpu_counter_batch); |
156 | |
157 | static void compute_batch_value(void) |
158 | { |
159 | int nr = num_online_cpus(); |
160 | |
161 | percpu_counter_batch = max(32, nr*2); |
162 | } |
163 | |
164 | static int percpu_counter_hotcpu_callback(struct notifier_block *nb, |
165 | unsigned long action, void *hcpu) |
166 | { |
167 | #ifdef CONFIG_HOTPLUG_CPU |
168 | unsigned int cpu; |
169 | struct percpu_counter *fbc; |
170 | |
171 | compute_batch_value(); |
172 | if (action != CPU_DEAD && action != CPU_DEAD_FROZEN) |
173 | return NOTIFY_OK; |
174 | |
175 | cpu = (unsigned long)hcpu; |
176 | spin_lock(&percpu_counters_lock); |
177 | list_for_each_entry(fbc, &percpu_counters, list) { |
178 | s32 *pcount; |
179 | unsigned long flags; |
180 | |
181 | raw_spin_lock_irqsave(&fbc->lock, flags); |
182 | pcount = per_cpu_ptr(fbc->counters, cpu); |
183 | fbc->count += *pcount; |
184 | *pcount = 0; |
185 | raw_spin_unlock_irqrestore(&fbc->lock, flags); |
186 | } |
187 | spin_unlock(&percpu_counters_lock); |
188 | #endif |
189 | return NOTIFY_OK; |
190 | } |
191 | |
192 | /* |
193 | * Compare counter against given value. |
194 | * Return 1 if greater, 0 if equal and -1 if less |
195 | */ |
196 | int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs) |
197 | { |
198 | s64 count; |
199 | |
200 | count = percpu_counter_read(fbc); |
201 | /* Check to see if rough count will be sufficient for comparison */ |
202 | if (abs(count - rhs) > (percpu_counter_batch*num_online_cpus())) { |
203 | if (count > rhs) |
204 | return 1; |
205 | else |
206 | return -1; |
207 | } |
208 | /* Need to use precise count */ |
209 | count = percpu_counter_sum(fbc); |
210 | if (count > rhs) |
211 | return 1; |
212 | else if (count < rhs) |
213 | return -1; |
214 | else |
215 | return 0; |
216 | } |
217 | EXPORT_SYMBOL(percpu_counter_compare); |
218 | |
219 | static int __init percpu_counter_startup(void) |
220 | { |
221 | compute_batch_value(); |
222 | hotcpu_notifier(percpu_counter_hotcpu_callback, 0); |
223 | return 0; |
224 | } |
225 | module_init(percpu_counter_startup); |
226 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9