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timekeeping: Add persistent_clock_exist flag

In current kernel, there are several places which need to check whether there is a persistent clock for the platform. Current check is done by calling the read_persistent_clock() and validating its return value. So one optimization is to do the check only once in timekeeping_init(), and use a flag persistent_clock_exist to record it. v2: Add a has_persistent_clock() helper function, as suggested by John.

Feng Tang committed 13 years ago

Commit 31ade301 parent f0dbe812 files · +17 −5Browse files

Showing the changes to include/linux (1 of 2 files). Show all

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include/linux/time.h+6−0
@@ -115,6 +115,12 @@ static inline bool timespec_valid_strict(const struct timespec *ts) · 114 unmodified lines
115 return true;115 return true;
116}116}
117 117
118extern bool persistent_clock_exist;
119static inline bool has_persistent_clock(void)
120{
121 return persistent_clock_exist;
122}
123
118extern void read_persistent_clock(struct timespec *ts);124extern void read_persistent_clock(struct timespec *ts);
119extern void read_boot_clock(struct timespec *ts);125extern void read_boot_clock(struct timespec *ts);
120extern int update_persistent_clock(struct timespec now);126extern int update_persistent_clock(struct timespec now);