From 069569e025706f27f939785f86a94d5d8ce55dce Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Sun, 22 Feb 2009 16:03:37 +0100 Subject: 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 --- kernel/time/ntp.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'kernel/time') diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c index 7447d57e021..a3fe7ef2d83 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; } -- cgit v1.2.3