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Commit 8f807f8d authored by Roman Zippel's avatar Roman Zippel Committed by Linus Torvalds
Browse files

[PATCH] ntp: add time_adjust to tick length 



This folds update_ntp_one_tick() into second_overflow() and adds time_adjust
to the tick length, this makes time_next_adjust unnecessary.  This slightly
changes the adjtime() behaviour, instead of applying it to the next tick, it's
applied to the next second.

Signed-off-by: default avatarRoman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 3d3675cc

include/linux/timex.h

+0 −1
Original line number Diff line number Diff line
@@ -217,7 +217,6 @@ extern long time_freq; /* frequency offset (scaled ppm) */ 
extern long time_reftime;	/* time at last adjustment (s) */



extern long time_adjust;	/* The amount of adjtime left */

extern long time_next_adjust;	/* Value for time_adjust at next tick */



extern void ntp_clear(void);

extern void ntp_update_frequency(void);

kernel/time/ntp.c

+18 −53
Original line number Diff line number Diff line
@@ -22,8 +22,9 @@ unsigned long tick_usec = TICK_USEC; /* USER_HZ period (usec) */ 
unsigned long tick_nsec;			/* ACTHZ period (nsec) */

static u64 tick_length, tick_length_base;



/* Don't completely fail for HZ > 500.  */

int tickadj = 500/HZ ? : 1;		/* microsecs */

#define MAX_TICKADJ		500		/* microsecs */

#define MAX_TICKADJ_SCALED	(((u64)(MAX_TICKADJ * NSEC_PER_USEC) << \

				  TICK_LENGTH_SHIFT) / HZ)



/*

 * phase-lock loop variables
@@ -40,7 +41,6 @@ long time_esterror = NTP_PHASE_LIMIT; /* estimated error (us) */ 
long time_freq;				/* frequency offset (scaled ppm)*/

long time_reftime;			/* time at last adjustment (s)	*/

long time_adjust;

long time_next_adjust;



/**

 * ntp_clear - Clears the NTP state variables
@@ -160,46 +160,19 @@ void second_overflow(void) 
	time_adj = max(time_adj, ((MAXPHASE / HZ) << SHIFT_UPDATE) / MINSEC);

	time_offset -= time_adj;

	tick_length += (s64)time_adj << (TICK_LENGTH_SHIFT - SHIFT_UPDATE);

}



/*

 * Returns how many microseconds we need to add to xtime this tick

 * in doing an adjustment requested with adjtime.

 */

static long adjtime_adjustment(void)

{

	long time_adjust_step;



	time_adjust_step = time_adjust;

	if (time_adjust_step) {

		/*

		 * We are doing an adjtime thing.  Prepare time_adjust_step to

		 * be within bounds.  Note that a positive time_adjust means we

		 * want the clock to run faster.

		 *

		 * Limit the amount of the step to be in the range

		 * -tickadj .. +tickadj

		 */

		time_adjust_step = min(time_adjust_step, (long)tickadj);

		time_adjust_step = max(time_adjust_step, (long)-tickadj);

	}

	return time_adjust_step;

	if (unlikely(time_adjust)) {

		if (time_adjust > MAX_TICKADJ) {

			time_adjust -= MAX_TICKADJ;

			tick_length += MAX_TICKADJ_SCALED;

		} else if (time_adjust < -MAX_TICKADJ) {

			time_adjust += MAX_TICKADJ;

			tick_length -= MAX_TICKADJ_SCALED;

		} else {

			time_adjust = 0;

			tick_length += (s64)(time_adjust * NSEC_PER_USEC /

					     HZ) << TICK_LENGTH_SHIFT;

		}



/* in the NTP reference this is called "hardclock()" */

void update_ntp_one_tick(void)

{

	long time_adjust_step;



	time_adjust_step = adjtime_adjustment();

	if (time_adjust_step)

		/* Reduce by this step the amount of time left  */

		time_adjust -= time_adjust_step;



	/* Changes by adjtime() do not take effect till next tick. */

	if (time_next_adjust != 0) {

		time_adjust = time_next_adjust;

		time_next_adjust = 0;

	}

}
@@ -213,14 +186,7 @@ void update_ntp_one_tick(void) 
 */

u64 current_tick_length(void)

{

	u64 ret;



	/* calculate the finest interval NTP will allow.

	 */

	ret = tick_length;

	ret += (u64)(adjtime_adjustment() * 1000) << TICK_LENGTH_SHIFT;



	return ret;

	return tick_length;

}
@@ -263,7 +229,7 @@ int do_adjtimex(struct timex *txc) 
	result = time_state;	/* mostly `TIME_OK' */



	/* Save for later - semantics of adjtime is to return old value */

	save_adjust = time_next_adjust ? time_next_adjust : time_adjust;

	save_adjust = time_adjust;



#if 0	/* STA_CLOCKERR is never set yet */

	time_status &= ~STA_CLOCKERR;		/* reset STA_CLOCKERR */
@@ -310,8 +276,7 @@ int do_adjtimex(struct timex *txc) 
	    if (txc->modes & ADJ_OFFSET) {	/* values checked earlier */

		if (txc->modes == ADJ_OFFSET_SINGLESHOT) {

		    /* adjtime() is independent from ntp_adjtime() */

		    if ((time_next_adjust = txc->offset) == 0)

			 time_adjust = 0;

		    time_adjust = txc->offset;

		}

		else if (time_status & STA_PLL) {

		    ltemp = txc->offset;

kernel/timer.c

+0 −2
Original line number Diff line number Diff line
@@ -937,8 +937,6 @@ static void update_wall_time(void) 
		/* interpolator bits */

		time_interpolator_update(clock->xtime_interval

						>> clock->shift);

		/* increment the NTP state machine */

		update_ntp_one_tick();



		/* accumulate error between NTP and clock interval */

		clock->error += current_tick_length();