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authorIngo Molnar <mingo@elte.hu>2009-02-22 16:03:37 +0100
committerIngo Molnar <mingo@elte.hu>2009-02-25 18:38:16 +0100
commit069569e025706f27f939785f86a94d5d8ce55dce (patch)
tree49c563db54f77883dc5cd0ff1e381cf80898c0a5 /kernel/time/ntp.c
parent2b9d1496e7835a603c340e8f0dd81f4b74d5f248 (diff)
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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.c7
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;
}