diff options
author | Arnaldo Carvalho de Melo <acme@redhat.com> | 2007-11-21 14:02:58 (GMT) |
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committer | David S. Miller <davem@davemloft.net> | 2008-01-28 22:54:39 (GMT) |
commit | de4d1db369785c29d68915edfee0cb70e8199f4c (patch) | |
tree | 78979fc131145d4b2df3cd4721a811784126f05c /include | |
parent | 0c884439dbd7c895cce61c4974c8868b0f6cd4a1 (diff) | |
download | linux-fsl-qoriq-de4d1db369785c29d68915edfee0cb70e8199f4c.tar.xz |
[LIB]: Introduce struct pcounter
This just generalises what was introduced by Eric Dumazet for the struct proto
inuse field in 286ab3d46058840d68e5d7d52e316c1f7e98c59f:
[NET]: Define infrastructure to keep 'inuse' changes in an efficent SMP/NUMA way.
Please look at the comment in there to see the rationale.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
-rw-r--r-- | include/linux/pcounter.h | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/include/linux/pcounter.h b/include/linux/pcounter.h new file mode 100644 index 0000000..620aade --- /dev/null +++ b/include/linux/pcounter.h @@ -0,0 +1,102 @@ +#ifndef __LINUX_PCOUNTER_H +#define __LINUX_PCOUNTER_H + +struct pcounter { +#ifdef CONFIG_SMP + void (*add)(struct pcounter *self, int inc); + int (*getval)(const struct pcounter *self); + int *per_cpu_values; +#else + int val; +#endif +}; + +/* + * Special macros to let pcounters use a fast version of {getvalue|add} + * using a static percpu variable per pcounter instead of an allocated one, + * saving one dereference. + * This might be changed if/when dynamic percpu vars become fast. + */ +#ifdef CONFIG_SMP +#include <linux/cpumask.h> +#include <linux/percpu.h> + +#define DEFINE_PCOUNTER(NAME) \ +static DEFINE_PER_CPU(int, NAME##_pcounter_values); \ +static void NAME##_pcounter_add(struct pcounter *self, int inc) \ +{ \ + __get_cpu_var(NAME##_pcounter_values) += inc; \ +} \ + \ +static int NAME##_pcounter_getval(const struct pcounter *self) \ +{ \ + int res = 0, cpu; \ + \ + for_each_possible_cpu(cpu) \ + res += per_cpu(NAME##_pcounter_values, cpu); \ + return res; \ +} + +#define PCOUNTER_MEMBER_INITIALIZER(NAME, MEMBER) \ + MEMBER = { \ + .add = NAME##_pcounter_add, \ + .getval = NAME##_pcounter_getval, \ + } + +extern void pcounter_def_add(struct pcounter *self, int inc); +extern int pcounter_def_getval(const struct pcounter *self); + +static inline int pcounter_alloc(struct pcounter *self) +{ + int rc = 0; + if (self->add == NULL) { + self->per_cpu_values = alloc_percpu(int); + if (self->per_cpu_values != NULL) { + self->add = pcounter_def_add; + self->getval = pcounter_def_getval; + } else + rc = 1; + } + return rc; +} + +static inline void pcounter_free(struct pcounter *self) +{ + if (self->per_cpu_values != NULL) { + free_percpu(self->per_cpu_values); + self->per_cpu_values = NULL; + self->getval = NULL; + self->add = NULL; + } +} + +static inline void pcounter_add(struct pcounter *self, int inc) +{ + self->add(self, inc); +} + +static inline int pcounter_getval(const struct pcounter *self) +{ + return self->getval(self); +} + +#else /* CONFIG_SMP */ + +static inline void pcounter_add(struct pcounter *self, int inc) +{ + self->value += inc; +} + +static inline int pcounter_getval(const struct pcounter *self) +{ + return self->val; +} + +#define DEFINE_PCOUNTER(NAME) +#define PCOUNTER_MEMBER_INITIALIZER(NAME, MEMBER) +#define pcounter_alloc(self) 0 +#define pcounter_free(self) + +#endif /* CONFIG_SMP */ + +#endif /* __LINUX_PCOUNTER_H */ |