diff options
Diffstat (limited to 'include/linux/clocksource.h')
| -rw-r--r-- | include/linux/clocksource.h | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h index 55e434feec99..f0a7fb984413 100644 --- a/include/linux/clocksource.h +++ b/include/linux/clocksource.h @@ -45,7 +45,8 @@ struct clocksource; * @read: returns a cycle value * @mask: bitmask for two's complement * subtraction of non 64 bit counters - * @mult: cycle to nanosecond multiplier + * @mult: cycle to nanosecond multiplier (adjusted by NTP) + * @mult_orig: cycle to nanosecond multiplier (unadjusted by NTP) * @shift: cycle to nanosecond divisor (power of two) * @flags: flags describing special properties * @vread: vsyscall based read @@ -63,6 +64,7 @@ struct clocksource { cycle_t (*read)(void); cycle_t mask; u32 mult; + u32 mult_orig; u32 shift; unsigned long flags; cycle_t (*vread)(void); @@ -201,16 +203,17 @@ static inline void clocksource_calculate_interval(struct clocksource *c, { u64 tmp; - /* XXX - All of this could use a whole lot of optimization */ + /* Do the ns -> cycle conversion first, using original mult */ tmp = length_nsec; tmp <<= c->shift; - tmp += c->mult/2; - do_div(tmp, c->mult); + tmp += c->mult_orig/2; + do_div(tmp, c->mult_orig); c->cycle_interval = (cycle_t)tmp; if (c->cycle_interval == 0) c->cycle_interval = 1; + /* Go back from cycles -> shifted ns, this time use ntp adjused mult */ c->xtime_interval = (u64)c->cycle_interval * c->mult; } |