[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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
john stultz · Linus Torvalds
1 parent 771ee3b04e
Showing 4 changed files with 36 additions and 16 deletions Side-by-side Diff
include/linux/timex.h
kernel/hrtimer.c
kernel/time/ntp.c
kernel/timer.c
@@ -286,6 +286,13 @@
  
 #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);
  
@@ -128,15 +128,20 @@
 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);
 }
@@ -24,7 +24,7 @@
  
 #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 @@
  
 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 @@
 			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 @@
 		    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 @@
 		    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 @@
 	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;
@@ -890,7 +890,7 @@
 	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 @@
 	if (change_clocksource()) {
 		clock->error = 0;
 		clock->xtime_nsec = 0;
-		clocksource_calculate_interval(clock, tick_nsec);
+		clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);
 	}
 }
...	...	@@ -286,6 +286,13 @@
286	286
287	287	#define TICK_LENGTH_SHIFT 32
288	288
	289	+#ifdef CONFIG_NO_HZ
	290	+#define NTP_INTERVAL_FREQ (2)
	291	+#else
	292	+#define NTP_INTERVAL_FREQ (HZ)
	293	+#endif
	294	+#define NTP_INTERVAL_LENGTH (NSEC_PER_SEC/NTP_INTERVAL_FREQ)
	295	+
289	296	/* Returns how long ticks are at present, in ns / 2^(SHIFT_SCALE-10). */
290	297	extern u64 current_tick_length(void);
291	298
...	...	@@ -128,15 +128,20 @@
128	128	static void hrtimer_get_softirq_time(struct hrtimer_base *base)
129	129	{
130	130	ktime_t xtim, tomono;
	131	+ struct timespec xts;
131	132	unsigned long seq;
132	133
133	134	do {
134	135	seq = read_seqbegin(&xtime_lock);
135		- xtim = timespec_to_ktime(xtime);
136		- tomono = timespec_to_ktime(wall_to_monotonic);
137		-
	136	+#ifdef CONFIG_NO_HZ
	137	+ getnstimeofday(&xts);
	138	+#else
	139	+ xts = xtime;
	140	+#endif
138	141	} while (read_seqretry(&xtime_lock, seq));
139	142
	143	+ xtim = timespec_to_ktime(xts);
	144	+ tomono = timespec_to_ktime(wall_to_monotonic);
140	145	base[CLOCK_REALTIME].softirq_time = xtim;
141	146	base[CLOCK_MONOTONIC].softirq_time = ktime_add(xtim, tomono);
142	147	}
...	...	@@ -24,7 +24,7 @@
24	24
25	25	#define MAX_TICKADJ 500 /* microsecs */
26	26	#define MAX_TICKADJ_SCALED (((u64)(MAX_TICKADJ * NSEC_PER_USEC) << \
27		- TICK_LENGTH_SHIFT) / HZ)
	27	+ TICK_LENGTH_SHIFT) / NTP_INTERVAL_FREQ)
28	28
29	29	/*
30	30	* phase-lock loop variables
31	31
32	32
...	...	@@ -46,13 +46,17 @@
46	46
47	47	static void ntp_update_frequency(void)
48	48	{
49		- tick_length_base = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ) << TICK_LENGTH_SHIFT;
50		- tick_length_base += (s64)CLOCK_TICK_ADJUST << TICK_LENGTH_SHIFT;
51		- tick_length_base += (s64)time_freq << (TICK_LENGTH_SHIFT - SHIFT_NSEC);
	49	+ u64 second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ)
	50	+ << TICK_LENGTH_SHIFT;
	51	+ second_length += (s64)CLOCK_TICK_ADJUST << TICK_LENGTH_SHIFT;
	52	+ second_length += (s64)time_freq << (TICK_LENGTH_SHIFT - SHIFT_NSEC);
52	53
53		- do_div(tick_length_base, HZ);
	54	+ tick_length_base = second_length;
54	55
55		- tick_nsec = tick_length_base >> TICK_LENGTH_SHIFT;
	56	+ do_div(second_length, HZ);
	57	+ tick_nsec = second_length >> TICK_LENGTH_SHIFT;
	58	+
	59	+ do_div(tick_length_base, NTP_INTERVAL_FREQ);
56	60	}
57	61
58	62	/**
...	...	@@ -162,7 +166,7 @@
162	166	tick_length -= MAX_TICKADJ_SCALED;
163	167	} else {
164	168	tick_length += (s64)(time_adjust * NSEC_PER_USEC /
165		- HZ) << TICK_LENGTH_SHIFT;
	169	+ NTP_INTERVAL_FREQ) << TICK_LENGTH_SHIFT;
166	170	time_adjust = 0;
167	171	}
168	172	}
...	...	@@ -239,7 +243,8 @@
239	243	result = -EINVAL;
240	244	goto leave;
241	245	}
242		- time_freq = ((s64)txc->freq * NSEC_PER_USEC) >> (SHIFT_USEC - SHIFT_NSEC);
	246	+ time_freq = ((s64)txc->freq * NSEC_PER_USEC)
	247	+ >> (SHIFT_USEC - SHIFT_NSEC);
243	248	}
244	249
245	250	if (txc->modes & ADJ_MAXERROR) {
...	...	@@ -309,7 +314,8 @@
309	314	freq_adj += time_freq;
310	315	freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC);
311	316	time_freq = max(freq_adj, (s64)-MAXFREQ_NSEC);
312		- time_offset = (time_offset / HZ) << SHIFT_UPDATE;
	317	+ time_offset = (time_offset / NTP_INTERVAL_FREQ)
	318	+ << SHIFT_UPDATE;
313	319	} /* STA_PLL */
314	320	} /* txc->modes & ADJ_OFFSET */
315	321	if (txc->modes & ADJ_TICK)
...	...	@@ -324,8 +330,10 @@
324	330	if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
325	331	txc->offset = save_adjust;
326	332	else
327		- txc->offset = shift_right(time_offset, SHIFT_UPDATE) * HZ / 1000;
328		- txc->freq = (time_freq / NSEC_PER_USEC) << (SHIFT_USEC - SHIFT_NSEC);
	333	+ txc->offset = shift_right(time_offset, SHIFT_UPDATE)
	334	+ * NTP_INTERVAL_FREQ / 1000;
	335	+ txc->freq = (time_freq / NSEC_PER_USEC)
	336	+ << (SHIFT_USEC - SHIFT_NSEC);
329	337	txc->maxerror = time_maxerror;
330	338	txc->esterror = time_esterror;
331	339	txc->status = time_status;
...	...	@@ -890,7 +890,7 @@
890	890	ntp_clear();
891	891
892	892	clock = clocksource_get_next();
893		- clocksource_calculate_interval(clock, tick_nsec);
	893	+ clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);
894	894	clock->cycle_last = clocksource_read(clock);
895	895
896	896	write_sequnlock_irqrestore(&xtime_lock, flags);
...	...	@@ -1092,7 +1092,7 @@
1092	1092	if (change_clocksource()) {
1093	1093	clock->error = 0;
1094	1094	clock->xtime_nsec = 0;
1095		- clocksource_calculate_interval(clock, tick_nsec);
	1095	+ clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);
1096	1096	}
1097	1097	}
1098	1098