[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 <dada1@cosmosbay.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -1,41 +1,39 @@
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#ifndef __LINUX_PCOUNTER_H
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#define __LINUX_PCOUNTER_H
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/*
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* Using a dynamic percpu 'int' variable has a cost :
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* 1) Extra dereference
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* Current per_cpu_ptr() implementation uses an array per 'percpu variable'.
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* 2) memory cost of NR_CPUS*(32+sizeof(void *)) instead of num_possible_cpus()*4
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*
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* This pcounter implementation is an abstraction to be able to use
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* either a static or a dynamic per cpu variable.
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* One dynamic per cpu variable gets a fast & cheap implementation, we can
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* change pcounter implementation too.
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*/
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struct pcounter {
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#ifdef CONFIG_SMP
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void (*add)(struct pcounter *self, int inc);
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int (*getval)(const struct pcounter *self);
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int (*getval)(const struct pcounter *self, int cpu);
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int *per_cpu_values;
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#else
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int val;
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#endif
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};
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/*
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* Special macros to let pcounters use a fast version of {getvalue|add}
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* using a static percpu variable per pcounter instead of an allocated one,
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* saving one dereference.
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* This might be changed if/when dynamic percpu vars become fast.
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*/
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#ifdef CONFIG_SMP
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#include <linux/cpumask.h>
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#include <linux/percpu.h>
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#define DEFINE_PCOUNTER(NAME) \
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static DEFINE_PER_CPU(int, NAME##_pcounter_values); \
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static void NAME##_pcounter_add(struct pcounter *self, int inc) \
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{ \
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__get_cpu_var(NAME##_pcounter_values) += inc; \
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} \
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\
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static int NAME##_pcounter_getval(const struct pcounter *self) \
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{ \
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int res = 0, cpu; \
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\
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for_each_possible_cpu(cpu) \
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res += per_cpu(NAME##_pcounter_values, cpu); \
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return res; \
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}
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#define DEFINE_PCOUNTER(NAME) \
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static DEFINE_PER_CPU(int, NAME##_pcounter_values); \
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static void NAME##_pcounter_add(struct pcounter *self, int val) \
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{ \
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__get_cpu_var(NAME##_pcounter_values) += val; \
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} \
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static int NAME##_pcounter_getval(const struct pcounter *self, int cpu) \
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{ \
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return per_cpu(NAME##_pcounter_values, cpu); \
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} \
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#define PCOUNTER_MEMBER_INITIALIZER(NAME, MEMBER) \
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MEMBER = { \
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@ -43,42 +41,16 @@ static int NAME##_pcounter_getval(const struct pcounter *self) \
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.getval = NAME##_pcounter_getval, \
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}
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extern void pcounter_def_add(struct pcounter *self, int inc);
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extern int pcounter_def_getval(const struct pcounter *self);
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static inline int pcounter_alloc(struct pcounter *self)
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{
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int rc = 0;
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if (self->add == NULL) {
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self->per_cpu_values = alloc_percpu(int);
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if (self->per_cpu_values != NULL) {
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self->add = pcounter_def_add;
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self->getval = pcounter_def_getval;
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} else
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rc = 1;
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}
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return rc;
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}
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static inline void pcounter_free(struct pcounter *self)
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{
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if (self->per_cpu_values != NULL) {
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free_percpu(self->per_cpu_values);
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self->per_cpu_values = NULL;
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self->getval = NULL;
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self->add = NULL;
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}
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}
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static inline void pcounter_add(struct pcounter *self, int inc)
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{
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self->add(self, inc);
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}
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static inline int pcounter_getval(const struct pcounter *self)
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{
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return self->getval(self);
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}
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extern int pcounter_getval(const struct pcounter *self);
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extern int pcounter_alloc(struct pcounter *self);
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extern void pcounter_free(struct pcounter *self);
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#else /* CONFIG_SMP */
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@ -7,20 +7,52 @@
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#include <linux/module.h>
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#include <linux/pcounter.h>
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#include <linux/smp.h>
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#include <linux/cpumask.h>
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void pcounter_def_add(struct pcounter *self, int inc)
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static void pcounter_dyn_add(struct pcounter *self, int inc)
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{
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per_cpu_ptr(self->per_cpu_values, smp_processor_id())[0] += inc;
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}
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EXPORT_SYMBOL_GPL(pcounter_def_add);
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int pcounter_def_getval(const struct pcounter *self)
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static int pcounter_dyn_getval(const struct pcounter *self, int cpu)
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{
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int res = 0, cpu;
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for_each_possible_cpu(cpu)
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res += per_cpu_ptr(self->per_cpu_values, cpu)[0];
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return res;
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return per_cpu_ptr(self->per_cpu_values, cpu)[0];
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}
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EXPORT_SYMBOL_GPL(pcounter_def_getval);
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int pcounter_getval(const struct pcounter *self)
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{
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int res = 0, cpu;
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for_each_possible_cpu(cpu)
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res += self->getval(self, cpu);
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return res;
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}
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EXPORT_SYMBOL_GPL(pcounter_getval);
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int pcounter_alloc(struct pcounter *self)
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{
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int rc = 0;
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if (self->add == NULL) {
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self->per_cpu_values = alloc_percpu(int);
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if (self->per_cpu_values != NULL) {
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self->add = pcounter_dyn_add;
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self->getval = pcounter_dyn_getval;
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} else
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rc = 1;
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}
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return rc;
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}
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EXPORT_SYMBOL_GPL(pcounter_alloc);
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void pcounter_free(struct pcounter *self)
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{
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if (self->per_cpu_values != NULL) {
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free_percpu(self->per_cpu_values);
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self->per_cpu_values = NULL;
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self->getval = NULL;
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self->add = NULL;
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}
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}
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EXPORT_SYMBOL_GPL(pcounter_free);
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