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time: ntp: simplify ntp_tick_adj calculations

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Impact: micro-optimization

Convert the (internal) ntp_tick_adj value we store from unscaled
units to scaled units. This is a constant that we never modify,
so scaling it up once during bootup is enough - we dont have to
do it for every adjustment step.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar 2009-02-22 16:03:37 +01:00
parent 2b9d1496e7
commit 069569e025
1 changed files with 5 additions and 2 deletions
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7
kernel/time/ntp.c
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@ -71,7 +71,8 @@ static long time_reftime;
long time_adjust; long time_adjust;
static long ntp_tick_adj; /* constant (boot-param configurable) NTP tick adjustment (upscaled) */
static s64 ntp_tick_adj;
/* /*
* NTP methods: * NTP methods:
@ -89,7 +90,7 @@ static void ntp_update_frequency(void)
second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ) second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ)
<< NTP_SCALE_SHIFT; << NTP_SCALE_SHIFT;
second_length += (s64)ntp_tick_adj << NTP_SCALE_SHIFT; second_length += ntp_tick_adj;
second_length += time_freq; second_length += time_freq;
tick_nsec = div_u64(second_length, HZ) >> NTP_SCALE_SHIFT; tick_nsec = div_u64(second_length, HZ) >> NTP_SCALE_SHIFT;
@ -540,6 +541,8 @@ int do_adjtimex(struct timex *txc)
static int __init ntp_tick_adj_setup(char *str) static int __init ntp_tick_adj_setup(char *str)
{ {
ntp_tick_adj = simple_strtol(str, NULL, 0); ntp_tick_adj = simple_strtol(str, NULL, 0);
ntp_tick_adj <<= NTP_SCALE_SHIFT;
return 1; return 1;
} }