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| author | Ingo Molnar <mingo@elte.hu> | 2009-02-22 16:03:37 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-02-25 18:38:16 +0100 |
| commit | 069569e025706f27f939785f86a94d5d8ce55dce (patch) | |
| tree | 49c563db54f77883dc5cd0ff1e381cf80898c0a5 /kernel/time/ntp.c | |
| parent | 2b9d1496e7835a603c340e8f0dd81f4b74d5f248 (diff) | |
| download | linux-069569e025706f27f939785f86a94d5d8ce55dce.tar.gz linux-069569e025706f27f939785f86a94d5d8ce55dce.tar.bz2 linux-069569e025706f27f939785f86a94d5d8ce55dce.zip | |
time: ntp: simplify ntp_tick_adj calculations
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>
Diffstat (limited to 'kernel/time/ntp.c')
| -rw-r--r-- | kernel/time/ntp.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c index 7447d57e021a..a3fe7ef2d83b 100644 --- a/kernel/time/ntp.c +++ b/kernel/time/ntp.c @@ -71,7 +71,8 @@ static long time_reftime; long time_adjust; -static long ntp_tick_adj; +/* constant (boot-param configurable) NTP tick adjustment (upscaled) */ +static s64 ntp_tick_adj; /* * NTP methods: @@ -89,7 +90,7 @@ static void ntp_update_frequency(void) second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ) << NTP_SCALE_SHIFT; - second_length += (s64)ntp_tick_adj << NTP_SCALE_SHIFT; + second_length += ntp_tick_adj; second_length += time_freq; 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) { ntp_tick_adj = simple_strtol(str, NULL, 0); + ntp_tick_adj <<= NTP_SCALE_SHIFT; + return 1; } |