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Commit 069569e0 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

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: default avatarIngo Molnar <mingo@elte.hu>
parent 2b9d1496

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;

}