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authorLinus Torvalds <torvalds@linux-foundation.org>2008-01-29 22:54:01 +1100
committerLinus Torvalds <torvalds@linux-foundation.org>2008-01-29 22:54:01 +1100
commit0ba6c33bcddc64a54b5f1c25a696c4767dc76292 (patch)
tree62e616f97a4762d8e75bf732e4827af2d15d52c5 /include/linux/pcounter.h
parent21af0297c7e56024a5ccc4d8ad2a590f9ec371ba (diff)
parent85040bcb4643cba578839e953f25e2d1965d83d0 (diff)
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Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6.25
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6.25: (1470 commits) [IPV6] ADDRLABEL: Fix double free on label deletion. [PPP]: Sparse warning fixes. [IPV4] fib_trie: remove unneeded NULL check [IPV4] fib_trie: More whitespace cleanup. [NET_SCHED]: Use nla_policy for attribute validation in ematches [NET_SCHED]: Use nla_policy for attribute validation in actions [NET_SCHED]: Use nla_policy for attribute validation in classifiers [NET_SCHED]: Use nla_policy for attribute validation in packet schedulers [NET_SCHED]: sch_api: introduce constant for rate table size [NET_SCHED]: Use typeful attribute parsing helpers [NET_SCHED]: Use typeful attribute construction helpers [NET_SCHED]: Use NLA_PUT_STRING for string dumping [NET_SCHED]: Use nla_nest_start/nla_nest_end [NET_SCHED]: Propagate nla_parse return value [NET_SCHED]: act_api: use PTR_ERR in tcf_action_init/tcf_action_get [NET_SCHED]: act_api: use nlmsg_parse [NET_SCHED]: act_api: fix netlink API conversion bug [NET_SCHED]: sch_netem: use nla_parse_nested_compat [NET_SCHED]: sch_atm: fix format string warning [NETNS]: Add namespace for ICMP replying code. ...
Diffstat (limited to 'include/linux/pcounter.h')
-rw-r--r--include/linux/pcounter.h74
1 files changed, 74 insertions, 0 deletions
diff --git a/include/linux/pcounter.h b/include/linux/pcounter.h
new file mode 100644
index 00000000000..a82d9f2628c
--- /dev/null
+++ b/include/linux/pcounter.h
@@ -0,0 +1,74 @@
+#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 */