time: ntp: simplify ntp_tick_adj calculations (069569e0) · Commits · 戴 / test

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>

kernel/time/ntp.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -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;
		}

Admin message