Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=571e7682026fd0e25833d103a3eeb74be29bf199
Commit:     571e7682026fd0e25833d103a3eeb74be29bf199
Parent:     789675e216617b1331875c42a81f58227a06df91
Author:     Eric Dumazet <[EMAIL PROTECTED]>
AuthorDate: Thu Jan 3 20:41:28 2008 -0800
Committer:  David S. Miller <[EMAIL PROTECTED]>
CommitDate: Mon Jan 28 15:00:35 2008 -0800

    [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 <[EMAIL PROTECTED]>
    Signed-off-by: David S. Miller <[EMAIL PROTECTED]>
---
 include/linux/pcounter.h |  176 +++++++++++++++++++--------------------------
 lib/pcounter.c           |   42 ++++++++++--
 2 files changed, 111 insertions(+), 107 deletions(-)

diff --git a/include/linux/pcounter.h b/include/linux/pcounter.h
dissimilarity index 63%
index 9c4760a..a82d9f2 100644
--- a/include/linux/pcounter.h
+++ b/include/linux/pcounter.h
@@ -1,102 +1,74 @@
-#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->val += 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 */
+#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 cpu);
+       int             *per_cpu_values;
+#else
+       int             val;
+#endif
+};
+
+#ifdef CONFIG_SMP
+#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 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 = {                                              \
+               .add    = NAME##_pcounter_add,                  \
+               .getval = NAME##_pcounter_getval,               \
+       }
+
+
+static inline void pcounter_add(struct pcounter *self, int inc)
+{
+       self->add(self, inc);
+}
+
+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 */
+
+static inline void pcounter_add(struct pcounter *self, int inc)
+{
+       self->val += 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 */
diff --git a/lib/pcounter.c b/lib/pcounter.c
index 93feea5..9b56807 100644
--- a/lib/pcounter.c
+++ b/lib/pcounter.c
@@ -7,20 +7,52 @@
 #include <linux/module.h>
 #include <linux/pcounter.h>
 #include <linux/smp.h>
+#include <linux/cpumask.h>
 
-void pcounter_def_add(struct pcounter *self, int inc)
+static void pcounter_dyn_add(struct pcounter *self, int inc)
 {
        per_cpu_ptr(self->per_cpu_values, smp_processor_id())[0] += inc;
 }
 
-EXPORT_SYMBOL_GPL(pcounter_def_add);
+static int pcounter_dyn_getval(const struct pcounter *self, int cpu)
+{
+       return per_cpu_ptr(self->per_cpu_values, cpu)[0];
+}
 
-int pcounter_def_getval(const struct pcounter *self)
+int pcounter_getval(const struct pcounter *self)
 {
        int res = 0, cpu;
+
        for_each_possible_cpu(cpu)
-               res += per_cpu_ptr(self->per_cpu_values, cpu)[0];
+               res += self->getval(self, cpu);
+
        return res;
 }
+EXPORT_SYMBOL_GPL(pcounter_getval);
+
+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_dyn_add;
+                       self->getval = pcounter_dyn_getval;
+               } else
+                       rc = 1;
+       }
+       return rc;
+}
+EXPORT_SYMBOL_GPL(pcounter_alloc);
+
+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;
+       }
+}
+EXPORT_SYMBOL_GPL(pcounter_free);
 
-EXPORT_SYMBOL_GPL(pcounter_def_getval);
-
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