diff options
Diffstat (limited to 'include/linux')
-rw-r--r-- | include/linux/pcounter.h | 80 |
1 files changed, 26 insertions, 54 deletions
diff --git a/include/linux/pcounter.h b/include/linux/pcounter.h index 9c4760a328f3..a82d9f2628ca 100644 --- a/include/linux/pcounter.h +++ b/include/linux/pcounter.h | |||
@@ -1,41 +1,39 @@ | |||
1 | #ifndef __LINUX_PCOUNTER_H | 1 | #ifndef __LINUX_PCOUNTER_H |
2 | #define __LINUX_PCOUNTER_H | 2 | #define __LINUX_PCOUNTER_H |
3 | 3 | /* | |
4 | * Using a dynamic percpu 'int' variable has a cost : | ||
5 | * 1) Extra dereference | ||
6 | * Current per_cpu_ptr() implementation uses an array per 'percpu variable'. | ||
7 | * 2) memory cost of NR_CPUS*(32+sizeof(void *)) instead of num_possible_cpus()*4 | ||
8 | * | ||
9 | * This pcounter implementation is an abstraction to be able to use | ||
10 | * either a static or a dynamic per cpu variable. | ||
11 | * One dynamic per cpu variable gets a fast & cheap implementation, we can | ||
12 | * change pcounter implementation too. | ||
13 | */ | ||
4 | struct pcounter { | 14 | struct pcounter { |
5 | #ifdef CONFIG_SMP | 15 | #ifdef CONFIG_SMP |
6 | void (*add)(struct pcounter *self, int inc); | 16 | void (*add)(struct pcounter *self, int inc); |
7 | int (*getval)(const struct pcounter *self); | 17 | int (*getval)(const struct pcounter *self, int cpu); |
8 | int *per_cpu_values; | 18 | int *per_cpu_values; |
9 | #else | 19 | #else |
10 | int val; | 20 | int val; |
11 | #endif | 21 | #endif |
12 | }; | 22 | }; |
13 | 23 | ||
14 | /* | ||
15 | * Special macros to let pcounters use a fast version of {getvalue|add} | ||
16 | * using a static percpu variable per pcounter instead of an allocated one, | ||
17 | * saving one dereference. | ||
18 | * This might be changed if/when dynamic percpu vars become fast. | ||
19 | */ | ||
20 | #ifdef CONFIG_SMP | 24 | #ifdef CONFIG_SMP |
21 | #include <linux/cpumask.h> | ||
22 | #include <linux/percpu.h> | 25 | #include <linux/percpu.h> |
23 | 26 | ||
24 | #define DEFINE_PCOUNTER(NAME) \ | 27 | #define DEFINE_PCOUNTER(NAME) \ |
25 | static DEFINE_PER_CPU(int, NAME##_pcounter_values); \ | 28 | static DEFINE_PER_CPU(int, NAME##_pcounter_values); \ |
26 | static void NAME##_pcounter_add(struct pcounter *self, int inc) \ | 29 | static void NAME##_pcounter_add(struct pcounter *self, int val) \ |
27 | { \ | 30 | { \ |
28 | __get_cpu_var(NAME##_pcounter_values) += inc; \ | 31 | __get_cpu_var(NAME##_pcounter_values) += val; \ |
29 | } \ | 32 | } \ |
30 | \ | 33 | static int NAME##_pcounter_getval(const struct pcounter *self, int cpu) \ |
31 | static int NAME##_pcounter_getval(const struct pcounter *self) \ | 34 | { \ |
32 | { \ | 35 | return per_cpu(NAME##_pcounter_values, cpu); \ |
33 | int res = 0, cpu; \ | 36 | } \ |
34 | \ | ||
35 | for_each_possible_cpu(cpu) \ | ||
36 | res += per_cpu(NAME##_pcounter_values, cpu); \ | ||
37 | return res; \ | ||
38 | } | ||
39 | 37 | ||
40 | #define PCOUNTER_MEMBER_INITIALIZER(NAME, MEMBER) \ | 38 | #define PCOUNTER_MEMBER_INITIALIZER(NAME, MEMBER) \ |
41 | MEMBER = { \ | 39 | MEMBER = { \ |
@@ -43,42 +41,16 @@ static int NAME##_pcounter_getval(const struct pcounter *self) \ | |||
43 | .getval = NAME##_pcounter_getval, \ | 41 | .getval = NAME##_pcounter_getval, \ |
44 | } | 42 | } |
45 | 43 | ||
46 | extern void pcounter_def_add(struct pcounter *self, int inc); | ||
47 | extern int pcounter_def_getval(const struct pcounter *self); | ||
48 | |||
49 | static inline int pcounter_alloc(struct pcounter *self) | ||
50 | { | ||
51 | int rc = 0; | ||
52 | if (self->add == NULL) { | ||
53 | self->per_cpu_values = alloc_percpu(int); | ||
54 | if (self->per_cpu_values != NULL) { | ||
55 | self->add = pcounter_def_add; | ||
56 | self->getval = pcounter_def_getval; | ||
57 | } else | ||
58 | rc = 1; | ||
59 | } | ||
60 | return rc; | ||
61 | } | ||
62 | |||
63 | static inline void pcounter_free(struct pcounter *self) | ||
64 | { | ||
65 | if (self->per_cpu_values != NULL) { | ||
66 | free_percpu(self->per_cpu_values); | ||
67 | self->per_cpu_values = NULL; | ||
68 | self->getval = NULL; | ||
69 | self->add = NULL; | ||
70 | } | ||
71 | } | ||
72 | 44 | ||
73 | static inline void pcounter_add(struct pcounter *self, int inc) | 45 | static inline void pcounter_add(struct pcounter *self, int inc) |
74 | { | 46 | { |
75 | self->add(self, inc); | 47 | self->add(self, inc); |
76 | } | 48 | } |
77 | 49 | ||
78 | static inline int pcounter_getval(const struct pcounter *self) | 50 | extern int pcounter_getval(const struct pcounter *self); |
79 | { | 51 | extern int pcounter_alloc(struct pcounter *self); |
80 | return self->getval(self); | 52 | extern void pcounter_free(struct pcounter *self); |
81 | } | 53 | |
82 | 54 | ||
83 | #else /* CONFIG_SMP */ | 55 | #else /* CONFIG_SMP */ |
84 | 56 | ||