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Commit f4304ab2 authored by John Stultz's avatar John Stultz Committed by Linus Torvalds
Browse files

[PATCH] HZ free ntp 



Distangle the NTP update from HZ.  This is necessary for dynamic tick enabled
kernels.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 771ee3b0

include/linux/timex.h

+7 −0
Original line number Diff line number Diff line
@@ -286,6 +286,13 @@ static inline void time_interpolator_update(long delta_nsec) 


#define TICK_LENGTH_SHIFT	32



#ifdef CONFIG_NO_HZ

#define NTP_INTERVAL_FREQ  (2)

#else

#define NTP_INTERVAL_FREQ  (HZ)

#endif

#define NTP_INTERVAL_LENGTH (NSEC_PER_SEC/NTP_INTERVAL_FREQ)



/* Returns how long ticks are at present, in ns / 2^(SHIFT_SCALE-10). */

extern u64 current_tick_length(void);

kernel/hrtimer.c

+8 −3
Original line number Diff line number Diff line
@@ -128,15 +128,20 @@ EXPORT_SYMBOL_GPL(ktime_get_ts); 
static void hrtimer_get_softirq_time(struct hrtimer_base *base)

{

	ktime_t xtim, tomono;

	struct timespec xts;

	unsigned long seq;



	do {

		seq = read_seqbegin(&xtime_lock);

		xtim = timespec_to_ktime(xtime);

		tomono = timespec_to_ktime(wall_to_monotonic);



#ifdef CONFIG_NO_HZ

		getnstimeofday(&xts);

#else

		xts = xtime;

#endif

	} while (read_seqretry(&xtime_lock, seq));



	xtim = timespec_to_ktime(xts);

	tomono = timespec_to_ktime(wall_to_monotonic);

	base[CLOCK_REALTIME].softirq_time = xtim;

	base[CLOCK_MONOTONIC].softirq_time = ktime_add(xtim, tomono);

}

kernel/time/ntp.c

+19 −11
Original line number Diff line number Diff line
@@ -24,7 +24,7 @@ static u64 tick_length, tick_length_base; 


#define MAX_TICKADJ		500		/* microsecs */

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

				  TICK_LENGTH_SHIFT) / HZ)

				  TICK_LENGTH_SHIFT) / NTP_INTERVAL_FREQ)



/*

 * phase-lock loop variables
@@ -46,13 +46,17 @@ long time_adjust; 


static void ntp_update_frequency(void)

{

	tick_length_base = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ) << TICK_LENGTH_SHIFT;

	tick_length_base += (s64)CLOCK_TICK_ADJUST << TICK_LENGTH_SHIFT;

	tick_length_base += (s64)time_freq << (TICK_LENGTH_SHIFT - SHIFT_NSEC);

	u64 second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ)

				<< TICK_LENGTH_SHIFT;

	second_length += (s64)CLOCK_TICK_ADJUST << TICK_LENGTH_SHIFT;

	second_length += (s64)time_freq << (TICK_LENGTH_SHIFT - SHIFT_NSEC);



	do_div(tick_length_base, HZ);

	tick_length_base = second_length;



	tick_nsec = tick_length_base >> TICK_LENGTH_SHIFT;

	do_div(second_length, HZ);

	tick_nsec = second_length >> TICK_LENGTH_SHIFT;



	do_div(tick_length_base, NTP_INTERVAL_FREQ);

}



/**
@@ -162,7 +166,7 @@ void second_overflow(void) 
			tick_length -= MAX_TICKADJ_SCALED;

		} else {

			tick_length += (s64)(time_adjust * NSEC_PER_USEC /

					     HZ) << TICK_LENGTH_SHIFT;

					NTP_INTERVAL_FREQ) << TICK_LENGTH_SHIFT;

			time_adjust = 0;

		}

	}
@@ -239,7 +243,8 @@ int do_adjtimex(struct timex *txc) 
		    result = -EINVAL;

		    goto leave;

		}

		time_freq = ((s64)txc->freq * NSEC_PER_USEC) >> (SHIFT_USEC - SHIFT_NSEC);

		time_freq = ((s64)txc->freq * NSEC_PER_USEC)

				>> (SHIFT_USEC - SHIFT_NSEC);

	    }



	    if (txc->modes & ADJ_MAXERROR) {
@@ -309,7 +314,8 @@ int do_adjtimex(struct timex *txc) 
		    freq_adj += time_freq;

		    freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC);

		    time_freq = max(freq_adj, (s64)-MAXFREQ_NSEC);

		    time_offset = (time_offset / HZ) << SHIFT_UPDATE;

		    time_offset = (time_offset / NTP_INTERVAL_FREQ)

		    			<< SHIFT_UPDATE;

		} /* STA_PLL */

	    } /* txc->modes & ADJ_OFFSET */

	    if (txc->modes & ADJ_TICK)
@@ -324,8 +330,10 @@ leave: if ((time_status & (STA_UNSYNC|STA_CLOCKERR)) != 0) 
	if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)

	    txc->offset	   = save_adjust;

	else

	    txc->offset    = shift_right(time_offset, SHIFT_UPDATE) * HZ / 1000;

	txc->freq	   = (time_freq / NSEC_PER_USEC) << (SHIFT_USEC - SHIFT_NSEC);

	    txc->offset    = shift_right(time_offset, SHIFT_UPDATE)

	    			* NTP_INTERVAL_FREQ / 1000;

	txc->freq	   = (time_freq / NSEC_PER_USEC)

				<< (SHIFT_USEC - SHIFT_NSEC);

	txc->maxerror	   = time_maxerror;

	txc->esterror	   = time_esterror;

	txc->status	   = time_status;

kernel/timer.c

+2 −2
Original line number Diff line number Diff line
@@ -890,7 +890,7 @@ void __init timekeeping_init(void) 
	ntp_clear();



	clock = clocksource_get_next();

	clocksource_calculate_interval(clock, tick_nsec);

	clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);

	clock->cycle_last = clocksource_read(clock);



	write_sequnlock_irqrestore(&xtime_lock, flags);
@@ -1092,7 +1092,7 @@ static void update_wall_time(void) 
	if (change_clocksource()) {

		clock->error = 0;

		clock->xtime_nsec = 0;

		clocksource_calculate_interval(clock, tick_nsec);

		clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);

	}

}