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-rw-r--r--include/linux/average.h39
1 files changed, 39 insertions, 0 deletions
diff --git a/include/linux/average.h b/include/linux/average.h
index c6028fd742c1..60f8226c5652 100644
--- a/include/linux/average.h
+++ b/include/linux/average.h
@@ -27,4 +27,43 @@ static inline unsigned long ewma_read(const struct ewma *avg)
return avg->internal >> avg->factor;
}
+#define DECLARE_EWMA(name, _factor, _weight) \
+ struct ewma_##name { \
+ unsigned long internal; \
+ }; \
+ static inline void ewma_##name##_init(struct ewma_##name *e) \
+ { \
+ BUILD_BUG_ON(!__builtin_constant_p(_factor)); \
+ BUILD_BUG_ON(!__builtin_constant_p(_weight)); \
+ BUILD_BUG_ON_NOT_POWER_OF_2(_factor); \
+ BUILD_BUG_ON_NOT_POWER_OF_2(_weight); \
+ e->internal = 0; \
+ } \
+ static inline unsigned long \
+ ewma_##name##_read(struct ewma_##name *e) \
+ { \
+ BUILD_BUG_ON(!__builtin_constant_p(_factor)); \
+ BUILD_BUG_ON(!__builtin_constant_p(_weight)); \
+ BUILD_BUG_ON_NOT_POWER_OF_2(_factor); \
+ BUILD_BUG_ON_NOT_POWER_OF_2(_weight); \
+ return e->internal >> ilog2(_factor); \
+ } \
+ static inline void ewma_##name##_add(struct ewma_##name *e, \
+ unsigned long val) \
+ { \
+ unsigned long internal = ACCESS_ONCE(e->internal); \
+ unsigned long weight = ilog2(_weight); \
+ unsigned long factor = ilog2(_factor); \
+ \
+ BUILD_BUG_ON(!__builtin_constant_p(_factor)); \
+ BUILD_BUG_ON(!__builtin_constant_p(_weight)); \
+ BUILD_BUG_ON_NOT_POWER_OF_2(_factor); \
+ BUILD_BUG_ON_NOT_POWER_OF_2(_weight); \
+ \
+ ACCESS_ONCE(e->internal) = internal ? \
+ (((internal << weight) - internal) + \
+ (val << factor)) >> weight : \
+ (val << factor); \
+ }
+
#endif /* _LINUX_AVERAGE_H */