From de4d1db369785c29d68915edfee0cb70e8199f4c Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Wed, 21 Nov 2007 22:02:58 +0800 Subject: [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 Signed-off-by: Herbert Xu Signed-off-by: David S. Miller --- include/linux/pcounter.h | 102 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 102 insertions(+) create mode 100644 include/linux/pcounter.h (limited to 'include/linux/pcounter.h') diff --git a/include/linux/pcounter.h b/include/linux/pcounter.h new file mode 100644 index 000000000000..620aaded4e94 --- /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 +#include + +#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 */ -- cgit v1.2.3 From e7d0362dd41e760f340c1b500646cc92522bd9d5 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Mon, 26 Nov 2007 23:34:54 +0800 Subject: [PCOUNTER] Fix build error without CONFIG_SMP MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit I keep getting this build error and couldn't find anyone fixing it in archives. ...Maybe all net developers except me build just SMP kernels :-). In file included from include/net/sock.h:50, from ipc/mqueue.c:35: include/linux/pcounter.h: In function 'pcounter_add': include/linux/pcounter.h:87: error: 'struct pcounter' has no member named 'value' make[1]: *** [ipc/mqueue.o] Error 1 make: *** [ipc] Error 2 Signed-off-by: Ilpo Järvinen Acked-by: Arnaldo Carvalho de Melo Signed-off-by: Herbert Xu Signed-off-by: David S. Miller --- include/linux/pcounter.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/pcounter.h') diff --git a/include/linux/pcounter.h b/include/linux/pcounter.h index 620aaded4e94..9c4760a328f3 100644 --- a/include/linux/pcounter.h +++ b/include/linux/pcounter.h @@ -84,7 +84,7 @@ static inline int pcounter_getval(const struct pcounter *self) static inline void pcounter_add(struct pcounter *self, int inc) { - self->value += inc; + self->val += inc; } static inline int pcounter_getval(const struct pcounter *self) -- cgit v1.2.3 From 571e7682026fd0e25833d103a3eeb74be29bf199 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 3 Jan 2008 20:41:28 -0800 Subject: [LIB] pcounter : unline too big functions Before pushing pcounter to Linus tree, I would like to make some adjustments. Goal is to reduce kernel text size, by unlining too big functions. When a pcounter is bound to a statically defined per_cpu variable, we define two small helpers functions. (No more folding function using the fat for_each_possible_cpu(cpu) ... ) static DEFINE_PER_CPU(int, NAME##_pcounter_values); static void NAME##_pcounter_add(struct pcounter *self, int val) { __get_cpu_var(NAME##_pcounter_values) += val; } static int NAME##_pcounter_getval(const struct pcounter *self, int cpu) { return per_cpu(NAME##_pcounter_values, cpu); } Fast path is therefore unchanged, while folding/alloc/free is now unlined. This saves 228 bytes on i386 Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/linux/pcounter.h | 80 ++++++++++++++++-------------------------------- 1 file changed, 26 insertions(+), 54 deletions(-) (limited to 'include/linux/pcounter.h') 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 @@ #ifndef __LINUX_PCOUNTER_H #define __LINUX_PCOUNTER_H - +/* + * Using a dynamic percpu 'int' variable has a cost : + * 1) Extra dereference + * Current per_cpu_ptr() implementation uses an array per 'percpu variable'. + * 2) memory cost of NR_CPUS*(32+sizeof(void *)) instead of num_possible_cpus()*4 + * + * This pcounter implementation is an abstraction to be able to use + * either a static or a dynamic per cpu variable. + * One dynamic per cpu variable gets a fast & cheap implementation, we can + * change pcounter implementation too. + */ struct pcounter { #ifdef CONFIG_SMP void (*add)(struct pcounter *self, int inc); - int (*getval)(const struct pcounter *self); + int (*getval)(const struct pcounter *self, int cpu); 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 #include -#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 DEFINE_PCOUNTER(NAME) \ +static DEFINE_PER_CPU(int, NAME##_pcounter_values); \ +static void NAME##_pcounter_add(struct pcounter *self, int val) \ +{ \ + __get_cpu_var(NAME##_pcounter_values) += val; \ +} \ +static int NAME##_pcounter_getval(const struct pcounter *self, int cpu) \ +{ \ + return per_cpu(NAME##_pcounter_values, cpu); \ +} \ #define PCOUNTER_MEMBER_INITIALIZER(NAME, MEMBER) \ MEMBER = { \ @@ -43,42 +41,16 @@ static int NAME##_pcounter_getval(const struct pcounter *self) \ .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); -} +extern int pcounter_getval(const struct pcounter *self); +extern int pcounter_alloc(struct pcounter *self); +extern void pcounter_free(struct pcounter *self); + #else /* CONFIG_SMP */ -- cgit v1.2.3