[Linux-ia64] gettimeoffset for 2.5.67

[Linux-ia64] gettimeoffset for 2.5.67

[Jes Sorensen]

Hi,

Here it is finally, the long awaited gettimeoffset patch for 2.5.x. It's
basically a forward port of my fix for 2.4.21, taking into account that
gettimeoffset() returns a nanosecond offset now.

Patch is relative to David's 2.5.67 0416 release.

Cheers,
Jes

diff -urN -X /home/jes/exclude-linux linux-2.5.67-vanilla/arch/ia64/kernel/time.c linux-2.5.67/arch/ia64/kernel/time.c
--- linux-2.5.67-vanilla/arch/ia64/kernel/time.c	Thu May  8 09:30:37 2003
+++ linux-2.5.67/arch/ia64/kernel/time.c	Thu May  8 10:41:19 2003
@@ -17,6 +17,7 @@
 #include <linux/time.h>
 #include <linux/interrupt.h>
 #include <linux/efi.h>
+#include <linux/timex.h>
 
 #include <asm/delay.h>
 #include <asm/hw_irq.h>
@@ -26,9 +27,14 @@
 
 extern unsigned long wall_jiffies;
 extern unsigned long last_nsec_offset;
+static unsigned long __ia64_gettimeoffset (void);
+
+unsigned long (*gettimeoffset)(void) = &__ia64_gettimeoffset;
 
 u64 jiffies_64 = INITIAL_JIFFIES;
 
+#define TIME_KEEPER_ID	0	/* smp_processor_id() of time-keeper */
+
 #ifdef CONFIG_IA64_DEBUG_IRQ
 
 unsigned long last_cli_ip;
@@ -63,15 +69,14 @@
  * Return the number of nano-seconds that elapsed since the last update to jiffy.  The
  * xtime_lock must be at least read-locked when calling this routine.
  */
-static inline unsigned long
-gettimeoffset (void)
+static unsigned long
+__ia64_gettimeoffset (void)
 {
 	unsigned long elapsed_cycles, lost = jiffies - wall_jiffies;
 	unsigned long now, last_tick;
-#	define time_keeper_id	0	/* smp_processor_id() of time-keeper */
 
-	last_tick = (cpu_data(time_keeper_id)->itm_next
-		     - (lost + 1)*cpu_data(time_keeper_id)->itm_delta);
+	last_tick = (cpu_data(TIME_KEEPER_ID)->itm_next
+		     - (lost + 1)*cpu_data(TIME_KEEPER_ID)->itm_delta);
 
 	now = ia64_get_itc();
 	if (unlikely((long) (now - last_tick) < 0)) {
@@ -110,6 +115,9 @@
 		time_status |= STA_UNSYNC;
 		time_maxerror = NTP_PHASE_LIMIT;
 		time_esterror = NTP_PHASE_LIMIT;
+		if (update_wall_time_hook)
+			update_wall_time_hook();
+
 	}
 	write_sequnlock_irq(&xtime_lock);
 	clock_was_set();
@@ -200,7 +208,7 @@
 #endif
 		new_itm += local_cpu_data->itm_delta;
 
-		if (smp_processor_id() = 0) {
+		if (smp_processor_id() = TIME_KEEPER_ID) {
 			/*
 			 * Here we are in the timer irq handler. We have irqs locally
 			 * disabled, but we don't know if the timer_bh is running on
diff -urN -X /home/jes/exclude-linux linux-2.5.67-vanilla/arch/ia64/sn/kernel/setup.c linux-2.5.67/arch/ia64/sn/kernel/setup.c
--- linux-2.5.67-vanilla/arch/ia64/sn/kernel/setup.c	Thu May  8 09:30:37 2003
+++ linux-2.5.67/arch/ia64/sn/kernel/setup.c	Thu May  8 09:55:32 2003
@@ -78,9 +78,9 @@
 
 extern void bte_init_node (nodepda_t *, cnodeid_t);
 extern void bte_init_cpu (void);
+extern void sn_timer_init (void);
 
 unsigned long sn_rtc_cycles_per_second;   
-unsigned long sn_rtc_usec_per_cyc;
 
 partid_t sn_partid = -1;
 char sn_system_serial_number_string[128];
@@ -263,13 +263,6 @@
 	else
 		sn_rtc_cycles_per_second = ticks_per_sec;
 
-#ifdef CONFIG_IA64_SGI_SN1
-	/* PROM has wrong value on SN1 */
-	sn_rtc_cycles_per_second = 990177;
-#endif
-	sn_rtc_usec_per_cyc = ((1000000000UL<<IA64_NSEC_PER_CYC_SHIFT)
-			       + sn_rtc_cycles_per_second/2) / sn_rtc_cycles_per_second;
-		
 	for (i=0;i<NR_CPUS;i++)
 		_sn_irq_desc[i] = _irq_desc;
 
@@ -309,6 +302,8 @@
 	 * Turn off "floating-point assist fault" warnings by default.
 	 */
 	current->thread.flags |= IA64_THREAD_FPEMU_NOPRINT;
+
+	sn_timer_init();
 }
 
 /**
diff -urN -X /home/jes/exclude-linux linux-2.5.67-vanilla/arch/ia64/sn/kernel/sn2/Makefile linux-2.5.67/arch/ia64/sn/kernel/sn2/Makefile
--- linux-2.5.67-vanilla/arch/ia64/sn/kernel/sn2/Makefile	Thu May  8 09:30:37 2003
+++ linux-2.5.67/arch/ia64/sn/kernel/sn2/Makefile	Thu May  8 09:50:06 2003
@@ -11,4 +11,4 @@
 
 EXTRA_CFLAGS := -DLITTLE_ENDIAN
 
-obj-y += cache.o iomv.o ptc_deadlock.o sn2_smp.o sn_proc_fs.o
+obj-y += cache.o iomv.o ptc_deadlock.o sn2_smp.o sn_proc_fs.o timer.o
diff -urN -X /home/jes/exclude-linux linux-2.5.67-vanilla/arch/ia64/sn/kernel/sn2/timer.c linux-2.5.67/arch/ia64/sn/kernel/sn2/timer.c
--- linux-2.5.67-vanilla/arch/ia64/sn/kernel/sn2/timer.c	Wed Dec 31 19:00:00 1969
+++ linux-2.5.67/arch/ia64/sn/kernel/sn2/timer.c	Thu May  8 12:35:38 2003
@@ -0,0 +1,85 @@
+/*
+ * linux/arch/ia64/sn/kernel/sn2/timer.c
+ *
+ * Copyright (C) 2003 Silicon Graphics, Inc.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/time.h>
+#include <linux/interrupt.h>
+
+#include <asm/hw_irq.h>
+#include <asm/system.h>
+
+#include <asm/sn/leds.h>
+#include <asm/sn/clksupport.h>
+
+
+extern unsigned long sn_rtc_cycles_per_second;
+static volatile unsigned long last_wall_rtc;
+
+/**
+ * gettimeoffset - number of nsecs elapsed since &xtime was last updated
+ *
+ * This function is used by do_gettimeofday() to determine the number
+ * of nsecs that have elapsed since the last update to &xtime.  On SN
+ * this is accomplished using the RTC built in to each Hub chip; each
+ * is guaranteed to be synchronized by the PROM, so a local read will
+ * suffice (GET_RTC_COUNTER() does this for us).  A snapshot of the RTC
+ * value is taken every time wall_jiffies is updated by the
+ * update_wall_time_hook (sn2_update_wall_time) which means we don't
+ * have to adjust for lost jiffies ticks or anything like that.
+ */
+
+static volatile long rtc_offset;
+static long rtc_nsecs_per_cycle;
+static long rtc_per_timer_tick;
+
+unsigned long
+sn_gettimeoffset(void)
+{
+	long current_rtc, elapsed_rtc, old, new_offset;
+
+	do {
+		old = rtc_offset;
+		current_rtc = GET_RTC_COUNTER();
+
+		/*
+		 * Need to address wrapping here!
+		 */
+		elapsed_rtc = (long)(current_rtc - last_wall_rtc);
+
+		new_offset = max(elapsed_rtc, old);
+	} while (cmpxchg(&rtc_offset, old, new_offset) != old);
+
+	return new_offset * rtc_nsecs_per_cycle;
+}
+
+
+void sn2_update_wall_time(void)
+{
+	rtc_offset -= min(rtc_offset, rtc_per_timer_tick);
+	last_wall_rtc = GET_RTC_COUNTER();
+}
+
+
+void sn2_reset_wall_time(void)
+{
+	rtc_offset = 0;
+	last_wall_rtc = GET_RTC_COUNTER();
+}
+
+
+void __init
+sn_timer_init(void)
+{
+	rtc_per_timer_tick = sn_rtc_cycles_per_second / HZ;
+	rtc_nsecs_per_cycle = 1000000000 / sn_rtc_cycles_per_second;
+
+	last_wall_rtc = GET_RTC_COUNTER();
+	update_wall_time_hook = sn2_update_wall_time;
+	reset_wall_time_hook = sn2_reset_wall_time;
+	gettimeoffset = sn_gettimeoffset;
+}
diff -urN -X /home/jes/exclude-linux linux-2.5.67-vanilla/include/asm-ia64/sn/clksupport.h linux-2.5.67/include/asm-ia64/sn/clksupport.h
--- linux-2.5.67-vanilla/include/asm-ia64/sn/clksupport.h	Mon Apr  7 13:31:56 2003
+++ linux-2.5.67/include/asm-ia64/sn/clksupport.h	Thu May  8 09:56:42 2003
@@ -38,7 +38,7 @@
 
 extern nasid_t master_nasid;
 
-#define RTC_MASK		(0x007fffffffffffff)
+#define RTC_MASK		0x007fffffffffffffUL
 /* clocks are not synchronized yet on SN1  - used node 0 (problem if no NASID 0) */
 #define RTC_COUNTER_ADDR	((clkreg_t*)REMOTE_HUB_ADDR(master_nasid, PI_RT_COUNTER))
 #define RTC_COMPARE_A_ADDR      ((clkreg_t*)REMOTE_HUB_ADDR(master_nasid, PI_RT_COMPARE_A))
@@ -52,7 +52,7 @@
 #include <asm/sn/sn2/addrs.h>
 #include <asm/sn/sn2/shubio.h>
 #include <asm/sn/sn2/shub_mmr.h>
-#define RTC_MASK		(SH_RTC_MASK)
+#define RTC_MASK		SH_RTC_MASK
 #define RTC_COUNTER_ADDR	((clkreg_t*)LOCAL_MMR_ADDR(SH_RTC))
 #define RTC_COMPARE_A_ADDR      ((clkreg_t*)LOCAL_MMR_ADDR(SH_RTC))
 #define RTC_COMPARE_B_ADDR      ((clkreg_t*)LOCAL_MMR_ADDR(SH_RTC))
@@ -62,7 +62,6 @@
 #define RTC_INT_ENABLED_B_ADDR  ((clkreg_t*)LOCAL_MMR_ADDR(SH_RTC))
 #endif	/* CONFIG_IA64_SGI_SN1 */
 
-
 #define GET_RTC_COUNTER()	(*RTC_COUNTER_ADDR)
 #define rtc_time()		GET_RTC_COUNTER()
 
diff -urN -X /home/jes/exclude-linux linux-2.5.67-vanilla/include/asm-ia64/timex.h linux-2.5.67/include/asm-ia64/timex.h
--- linux-2.5.67-vanilla/include/asm-ia64/timex.h	Mon Apr  7 13:32:27 2003
+++ linux-2.5.67/include/asm-ia64/timex.h	Thu May  8 09:52:10 2003
@@ -25,4 +25,6 @@
 	return ret;
 }
 
+extern unsigned long (*gettimeoffset)(void);
+
 #endif /* _ASM_IA64_TIMEX_H */
diff -urN -X /home/jes/exclude-linux linux-2.5.67-vanilla/include/linux/timex.h linux-2.5.67/include/linux/timex.h
--- linux-2.5.67-vanilla/include/linux/timex.h	Mon Apr  7 13:30:38 2003
+++ linux-2.5.67/include/linux/timex.h	Thu May  8 10:42:14 2003
@@ -310,6 +310,13 @@
 extern long pps_errcnt;		/* calibration errors */
 extern long pps_stbcnt;		/* stability limit exceeded */
 
+/*
+ * Call-back for high precision timer sources to snapshot every time
+ * wall_jiffies is updated.
+ */
+extern void (*update_wall_time_hook)(void);
+extern void (*reset_wall_time_hook)(void);
+
 #endif /* KERNEL */
 
 #endif /* LINUX_TIMEX_H */
diff -urN -X /home/jes/exclude-linux linux-2.5.67-vanilla/kernel/time.c linux-2.5.67/kernel/time.c
--- linux-2.5.67-vanilla/kernel/time.c	Thu May  8 09:30:37 2003
+++ linux-2.5.67/kernel/time.c	Thu May  8 09:58:05 2003
@@ -77,6 +77,9 @@
 	if (get_user(value, tptr))
 		return -EFAULT;
 	write_seqlock_irq(&xtime_lock);
+
+	if (reset_wall_time_hook)
+		reset_wall_time_hook();
 	xtime.tv_sec = value;
 	xtime.tv_nsec = 0;
 	last_nsec_offset = 0;
diff -urN -X /home/jes/exclude-linux linux-2.5.67-vanilla/kernel/timer.c linux-2.5.67/kernel/timer.c
--- linux-2.5.67-vanilla/kernel/timer.c	Thu May  8 09:30:37 2003
+++ linux-2.5.67/kernel/timer.c	Thu May  8 09:58:48 2003
@@ -674,6 +674,15 @@
 }
 
 /*
+ * Hook for using external high precision timers for the system clock.
+ * On systems where the CPU clock isn't synchronized between CPUs,
+ * it is necessary to use an external source such as an RTC to obtain
+ * precision in gettimeofday().
+ */
+void (*update_wall_time_hook)(void);
+void (*reset_wall_time_hook)(void);
+
+/*
  * Using a loop looks inefficient, but "ticks" is
  * usually just one (we shouldn't be losing ticks,
  * we're doing this this way mainly for interrupt
@@ -685,12 +694,17 @@
 	do {
 		ticks--;
 		update_wall_time_one_tick();
+
+		if (update_wall_time_hook)
+			update_wall_time_hook();
 	} while (ticks);
 
 	if (xtime.tv_nsec >= 1000000000) {
 	    xtime.tv_nsec -= 1000000000;
 	    xtime.tv_sec++;
 	    second_overflow();
+	    if (update_wall_time_hook)
+		    update_wall_time_hook();
 	}
 }
 

Re: [Linux-ia64] gettimeoffset for 2.5.67

[David Mosberger]

>>>>> On Thu, 8 May 2003 12:44:47 -0400, Jes Sorensen <jes@wildopensource.com> said:

  Jes> Here it is finally, the long awaited gettimeoffset patch for 2.5.x. It's
  Jes> basically a forward port of my fix for 2.4.21, taking into account that
  Jes> gettimeoffset() returns a nanosecond offset now.

  Jes> Patch is relative to David's 2.5.67 0416 release.

The patch looks largely fine to me.  It's missing an update to
fsys_gettimeofday() though.  In that routine, you need to check
whether the ITC_DRIFT flag is on and, if so, fall back on doing the
heavy-weight syscall.

BTW: There were some unrelated changes in the time code (for
CLOCK_MONOTONIC), which make it likely that your patch won't apply.
If you don't mind, wait with resubmitting the patch until 2.5.69 is
out (hopefully today or tomorrow).  But if you don't want to wait,
that's OK too, I'll do the merge, if necessary.

	--david

Re: [Linux-ia64] gettimeoffset for 2.5.67

[Jes Sorensen]

>>>>> "David" = David Mosberger <davidm@napali.hpl.hp.com> writes:

>>>>> On Thu, 8 May 2003 12:44:47 -0400, Jes Sorensen <jes@wildopensource.com> said:
Jes> Patch is relative to David's 2.5.67 0416 release.

David> The patch looks largely fine to me.  It's missing an update to
David> fsys_gettimeofday() though.  In that routine, you need to check
David> whether the ITC_DRIFT flag is on and, if so, fall back on doing
David> the heavy-weight syscall.

Hi David,

Here is the updated version relative to you 2.5.69 patch.
CLOCK_MONOTONIC didn't cause any problems to the patch btw.

I have added the check to fsys.S so for now we will stick to the slow
version for SN2, but I may look into fixing it to use the fast
syscalls for that at a later point. But lets get the kernel booting
first ... details, details ;-)

Tested on my zx1 and doesn't seem to cause any problems there.

Cheers,
Jes

diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/arch/ia64/kernel/fsys.S linux-2.5.69-030509/arch/ia64/kernel/fsys.S
--- linux-2.5.69-030509-vanilla/arch/ia64/kernel/fsys.S	Sun May  4 19:52:48 2003
+++ linux-2.5.69-030509/arch/ia64/kernel/fsys.S	Sun May 11 13:19:24 2003
@@ -142,21 +142,31 @@
  *	   we ought to either skip the ITC-based interpolation or run an ntp-like
  *	   daemon to keep the ITCs from drifting too far apart.
  */
+
+#define IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT	 	(1 << 3)
+
 ENTRY(fsys_gettimeofday)
 	add r9=TI_FLAGS+IA64_TASK_SIZE,r16
 	movl r3=THIS_CPU(cpu_info)
 
 	mov.m r31=ar.itc		// put time stamp into r31 (ITC) = now		(35 cyc)
 	movl r19=xtime			// xtime is a timespec struct
+#ifdef CONFIG_SMP
+	movl r2=sal_platform_features
+#endif
 	;;
 
 #ifdef CONFIG_SMP
+	ld8 r2=[r2]
 	movl r10=__per_cpu_offset
 	;;
 	ld8 r10=[r10]			// r10 <- __per_cpu_offset[0]
 	movl r21=cpu_info__per_cpu
+	and r2=IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT,r2
 	;;
 	add r10=r21, r10		// r10 <- &cpu_data(time_keeper_id)
+	cmp.ne p8, p0=0, r2
+(p8)	br.spnt.many fsys_fallback_syscall
 #else
 	mov r10=r3
 #endif
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/arch/ia64/kernel/time.c linux-2.5.69-030509/arch/ia64/kernel/time.c
--- linux-2.5.69-030509-vanilla/arch/ia64/kernel/time.c	Sun May 11 10:53:49 2003
+++ linux-2.5.69-030509/arch/ia64/kernel/time.c	Sun May 11 11:20:35 2003
@@ -17,6 +17,7 @@
 #include <linux/time.h>
 #include <linux/interrupt.h>
 #include <linux/efi.h>
+#include <linux/timex.h>
 
 #include <asm/delay.h>
 #include <asm/hw_irq.h>
@@ -26,9 +27,14 @@
 
 extern unsigned long wall_jiffies;
 extern unsigned long last_nsec_offset;
+static unsigned long __ia64_gettimeoffset (void);
+
+unsigned long (*gettimeoffset)(void) = &__ia64_gettimeoffset;
 
 u64 jiffies_64 = INITIAL_JIFFIES;
 
+#define TIME_KEEPER_ID	0	/* smp_processor_id() of time-keeper */
+
 #ifdef CONFIG_IA64_DEBUG_IRQ
 
 unsigned long last_cli_ip;
@@ -63,15 +69,14 @@
  * Return the number of nano-seconds that elapsed since the last update to jiffy.  The
  * xtime_lock must be at least read-locked when calling this routine.
  */
-static inline unsigned long
-gettimeoffset (void)
+static unsigned long
+__ia64_gettimeoffset (void)
 {
 	unsigned long elapsed_cycles, lost = jiffies - wall_jiffies;
 	unsigned long now, last_tick;
-#	define time_keeper_id	0	/* smp_processor_id() of time-keeper */
 
-	last_tick = (cpu_data(time_keeper_id)->itm_next
-		     - (lost + 1)*cpu_data(time_keeper_id)->itm_delta);
+	last_tick = (cpu_data(TIME_KEEPER_ID)->itm_next
+		     - (lost + 1)*cpu_data(TIME_KEEPER_ID)->itm_delta);
 
 	now = ia64_get_itc();
 	if (unlikely((long) (now - last_tick) < 0)) {
@@ -124,6 +129,9 @@
 		time_status |= STA_UNSYNC;
 		time_maxerror = NTP_PHASE_LIMIT;
 		time_esterror = NTP_PHASE_LIMIT;
+		if (update_wall_time_hook)
+			update_wall_time_hook();
+
 	}
 	write_sequnlock_irq(&xtime_lock);
 	clock_was_set();
@@ -214,7 +222,7 @@
 #endif
 		new_itm += local_cpu_data->itm_delta;
 
-		if (smp_processor_id() = 0) {
+		if (smp_processor_id() = TIME_KEEPER_ID) {
 			/*
 			 * Here we are in the timer irq handler. We have irqs locally
 			 * disabled, but we don't know if the timer_bh is running on
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/arch/ia64/sn/kernel/setup.c linux-2.5.69-030509/arch/ia64/sn/kernel/setup.c
--- linux-2.5.69-030509-vanilla/arch/ia64/sn/kernel/setup.c	Sun May  4 19:53:08 2003
+++ linux-2.5.69-030509/arch/ia64/sn/kernel/setup.c	Sun May 11 11:20:35 2003
@@ -78,9 +78,9 @@
 
 extern void bte_init_node (nodepda_t *, cnodeid_t);
 extern void bte_init_cpu (void);
+extern void sn_timer_init (void);
 
 unsigned long sn_rtc_cycles_per_second;   
-unsigned long sn_rtc_usec_per_cyc;
 
 partid_t sn_partid = -1;
 char sn_system_serial_number_string[128];
@@ -263,13 +263,6 @@
 	else
 		sn_rtc_cycles_per_second = ticks_per_sec;
 
-#ifdef CONFIG_IA64_SGI_SN1
-	/* PROM has wrong value on SN1 */
-	sn_rtc_cycles_per_second = 990177;
-#endif
-	sn_rtc_usec_per_cyc = ((1000000000UL<<IA64_NSEC_PER_CYC_SHIFT)
-			       + sn_rtc_cycles_per_second/2) / sn_rtc_cycles_per_second;
-		
 	for (i=0;i<NR_CPUS;i++)
 		_sn_irq_desc[i] = _irq_desc;
 
@@ -309,6 +302,8 @@
 	 * Turn off "floating-point assist fault" warnings by default.
 	 */
 	current->thread.flags |= IA64_THREAD_FPEMU_NOPRINT;
+
+	sn_timer_init();
 }
 
 /**
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/arch/ia64/sn/kernel/sn2/Makefile linux-2.5.69-030509/arch/ia64/sn/kernel/sn2/Makefile
--- linux-2.5.69-030509-vanilla/arch/ia64/sn/kernel/sn2/Makefile	Sun May  4 19:53:56 2003
+++ linux-2.5.69-030509/arch/ia64/sn/kernel/sn2/Makefile	Sun May 11 11:20:35 2003
@@ -11,4 +11,4 @@
 
 EXTRA_CFLAGS := -DLITTLE_ENDIAN
 
-obj-y += cache.o iomv.o ptc_deadlock.o sn2_smp.o sn_proc_fs.o
+obj-y += cache.o iomv.o ptc_deadlock.o sn2_smp.o sn_proc_fs.o timer.o
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/arch/ia64/sn/kernel/sn2/timer.c linux-2.5.69-030509/arch/ia64/sn/kernel/sn2/timer.c
--- linux-2.5.69-030509-vanilla/arch/ia64/sn/kernel/sn2/timer.c	Wed Dec 31 19:00:00 1969
+++ linux-2.5.69-030509/arch/ia64/sn/kernel/sn2/timer.c	Sun May 11 11:20:35 2003
@@ -0,0 +1,85 @@
+/*
+ * linux/arch/ia64/sn/kernel/sn2/timer.c
+ *
+ * Copyright (C) 2003 Silicon Graphics, Inc.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/time.h>
+#include <linux/interrupt.h>
+
+#include <asm/hw_irq.h>
+#include <asm/system.h>
+
+#include <asm/sn/leds.h>
+#include <asm/sn/clksupport.h>
+
+
+extern unsigned long sn_rtc_cycles_per_second;
+static volatile unsigned long last_wall_rtc;
+
+/**
+ * gettimeoffset - number of nsecs elapsed since &xtime was last updated
+ *
+ * This function is used by do_gettimeofday() to determine the number
+ * of nsecs that have elapsed since the last update to &xtime.  On SN
+ * this is accomplished using the RTC built in to each Hub chip; each
+ * is guaranteed to be synchronized by the PROM, so a local read will
+ * suffice (GET_RTC_COUNTER() does this for us).  A snapshot of the RTC
+ * value is taken every time wall_jiffies is updated by the
+ * update_wall_time_hook (sn2_update_wall_time) which means we don't
+ * have to adjust for lost jiffies ticks or anything like that.
+ */
+
+static volatile long rtc_offset;
+static long rtc_nsecs_per_cycle;
+static long rtc_per_timer_tick;
+
+unsigned long
+sn_gettimeoffset(void)
+{
+	long current_rtc, elapsed_rtc, old, new_offset;
+
+	do {
+		old = rtc_offset;
+		current_rtc = GET_RTC_COUNTER();
+
+		/*
+		 * Need to address wrapping here!
+		 */
+		elapsed_rtc = (long)(current_rtc - last_wall_rtc);
+
+		new_offset = max(elapsed_rtc, old);
+	} while (cmpxchg(&rtc_offset, old, new_offset) != old);
+
+	return new_offset * rtc_nsecs_per_cycle;
+}
+
+
+void sn2_update_wall_time(void)
+{
+	rtc_offset -= min(rtc_offset, rtc_per_timer_tick);
+	last_wall_rtc = GET_RTC_COUNTER();
+}
+
+
+void sn2_reset_wall_time(void)
+{
+	rtc_offset = 0;
+	last_wall_rtc = GET_RTC_COUNTER();
+}
+
+
+void __init
+sn_timer_init(void)
+{
+	rtc_per_timer_tick = sn_rtc_cycles_per_second / HZ;
+	rtc_nsecs_per_cycle = 1000000000 / sn_rtc_cycles_per_second;
+
+	last_wall_rtc = GET_RTC_COUNTER();
+	update_wall_time_hook = sn2_update_wall_time;
+	reset_wall_time_hook = sn2_reset_wall_time;
+	gettimeoffset = sn_gettimeoffset;
+}
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/include/asm-ia64/sn/clksupport.h linux-2.5.69-030509/include/asm-ia64/sn/clksupport.h
--- linux-2.5.69-030509-vanilla/include/asm-ia64/sn/clksupport.h	Sun May  4 19:53:35 2003
+++ linux-2.5.69-030509/include/asm-ia64/sn/clksupport.h	Sun May 11 11:20:35 2003
@@ -38,7 +38,7 @@
 
 extern nasid_t master_nasid;
 
-#define RTC_MASK		(0x007fffffffffffff)
+#define RTC_MASK		0x007fffffffffffffUL
 /* clocks are not synchronized yet on SN1  - used node 0 (problem if no NASID 0) */
 #define RTC_COUNTER_ADDR	((clkreg_t*)REMOTE_HUB_ADDR(master_nasid, PI_RT_COUNTER))
 #define RTC_COMPARE_A_ADDR      ((clkreg_t*)REMOTE_HUB_ADDR(master_nasid, PI_RT_COMPARE_A))
@@ -52,7 +52,7 @@
 #include <asm/sn/sn2/addrs.h>
 #include <asm/sn/sn2/shubio.h>
 #include <asm/sn/sn2/shub_mmr.h>
-#define RTC_MASK		(SH_RTC_MASK)
+#define RTC_MASK		SH_RTC_MASK
 #define RTC_COUNTER_ADDR	((clkreg_t*)LOCAL_MMR_ADDR(SH_RTC))
 #define RTC_COMPARE_A_ADDR      ((clkreg_t*)LOCAL_MMR_ADDR(SH_RTC))
 #define RTC_COMPARE_B_ADDR      ((clkreg_t*)LOCAL_MMR_ADDR(SH_RTC))
@@ -62,7 +62,6 @@
 #define RTC_INT_ENABLED_B_ADDR  ((clkreg_t*)LOCAL_MMR_ADDR(SH_RTC))
 #endif	/* CONFIG_IA64_SGI_SN1 */
 
-
 #define GET_RTC_COUNTER()	(*RTC_COUNTER_ADDR)
 #define rtc_time()		GET_RTC_COUNTER()
 
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/include/asm-ia64/timex.h linux-2.5.69-030509/include/asm-ia64/timex.h
--- linux-2.5.69-030509-vanilla/include/asm-ia64/timex.h	Sun May  4 19:53:40 2003
+++ linux-2.5.69-030509/include/asm-ia64/timex.h	Sun May 11 11:20:35 2003
@@ -25,4 +25,6 @@
 	return ret;
 }
 
+extern unsigned long (*gettimeoffset)(void);
+
 #endif /* _ASM_IA64_TIMEX_H */
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/include/linux/timex.h linux-2.5.69-030509/include/linux/timex.h
--- linux-2.5.69-030509-vanilla/include/linux/timex.h	Sun May  4 19:52:59 2003
+++ linux-2.5.69-030509/include/linux/timex.h	Sun May 11 11:20:35 2003
@@ -310,6 +310,13 @@
 extern long pps_errcnt;		/* calibration errors */
 extern long pps_stbcnt;		/* stability limit exceeded */
 
+/*
+ * Call-back for high precision timer sources to snapshot every time
+ * wall_jiffies is updated.
+ */
+extern void (*update_wall_time_hook)(void);
+extern void (*reset_wall_time_hook)(void);
+
 #endif /* KERNEL */
 
 #endif /* LINUX_TIMEX_H */
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/kernel/time.c linux-2.5.69-030509/kernel/time.c
--- linux-2.5.69-030509-vanilla/kernel/time.c	Sun May 11 10:53:49 2003
+++ linux-2.5.69-030509/kernel/time.c	Sun May 11 11:20:35 2003
@@ -77,6 +77,9 @@
 	if (get_user(value, tptr))
 		return -EFAULT;
 	write_seqlock_irq(&xtime_lock);
+
+	if (reset_wall_time_hook)
+		reset_wall_time_hook();
 	xtime.tv_sec = value;
 	xtime.tv_nsec = 0;
 	last_nsec_offset = 0;
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/kernel/timer.c linux-2.5.69-030509/kernel/timer.c
--- linux-2.5.69-030509-vanilla/kernel/timer.c	Sun May 11 10:53:49 2003
+++ linux-2.5.69-030509/kernel/timer.c	Sun May 11 11:20:35 2003
@@ -665,6 +665,15 @@
 }
 
 /*
+ * Hook for using external high precision timers for the system clock.
+ * On systems where the CPU clock isn't synchronized between CPUs,
+ * it is necessary to use an external source such as an RTC to obtain
+ * precision in gettimeofday().
+ */
+void (*update_wall_time_hook)(void);
+void (*reset_wall_time_hook)(void);
+
+/*
  * Using a loop looks inefficient, but "ticks" is
  * usually just one (we shouldn't be losing ticks,
  * we're doing this this way mainly for interrupt
@@ -676,12 +685,17 @@
 	do {
 		ticks--;
 		update_wall_time_one_tick();
+
+		if (update_wall_time_hook)
+			update_wall_time_hook();
 	} while (ticks);
 
 	if (xtime.tv_nsec >= 1000000000) {
 	    xtime.tv_nsec -= 1000000000;
 	    xtime.tv_sec++;
 	    second_overflow();
+	    if (update_wall_time_hook)
+		    update_wall_time_hook();
 	}
 }
 

Re: [Linux-ia64] gettimeoffset for 2.5.67

[David Mosberger]

>>>>> On 11 May 2003 13:54:29 -0400, Jes Sorensen <jes@wildopensource.com> said:

>>>>> "David" = David Mosberger <davidm@napali.hpl.hp.com> writes:
>>>>> On Thu, 8 May 2003 12:44:47 -0400, Jes Sorensen <jes@wildopensource.com> said:

  Jes> I have added the check to fsys.S so for now we will stick to
  Jes> the slow version for SN2, but I may look into fixing it to use
  Jes> the fast syscalls for that at a later point. But lets get the
  Jes> kernel booting first ... details, details ;-)

  Jes> diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/arch/ia64/kernel/fsys.S linux-2.5.69-030509/arch/ia64/kernel/fsys.S
  Jes> --- linux-2.5.69-030509-vanilla/arch/ia64/kernel/fsys.S	Sun May  4 19:52:48 2003
  Jes> +++ linux-2.5.69-030509/arch/ia64/kernel/fsys.S	Sun May 11 13:19:24 2003
  Jes> @@ -142,21 +142,31 @@
  Jes>   *	   we ought to either skip the ITC-based interpolation or run an ntp-like
  Jes>   *	   daemon to keep the ITCs from drifting too far apart.
  Jes>   */
  Jes> +
  Jes> +#define IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT	 	(1 << 3)
  Jes> +

This is not good.  The definition is already in sal.h.  Please lets
fix sal.h instead so it can be included by assembly code (i.e., change
sal.h so that the #define's come first, then check for #ifndef
__ASSEMBLY__".  Also, what's the impact of adding the the extra check
to the fsys_gettimeofday()?  Did you verify that the resulting
bundling is still near optimal?

Also, (not in reference to this particular patch): when you send code
that calls through a function pointer, I'd really like to see the
dereferencing there (for anything that goes in arch/ia64 or
include/asm-ia64, I mean).  I know some kernel folks feel differently
about this, but it's very misleading to write:

	foo(...);

instead of

	(*foo)(...);

The former cannot reasonably fail (in the absence of weak symbols),
whereas the latter certainly can (and usually seems to... ;-).

Thanks,

	--david

Re: [Linux-ia64] gettimeoffset for 2.5.67

[Jes Sorensen]

>>>>> "David" = David Mosberger <davidm@napali.hpl.hp.com> writes:

David> This is not good.  The definition is already in sal.h.  Please
David> lets fix sal.h instead so it can be included by assembly code
David> (i.e., change sal.h so that the #define's come first, then
David> check for #ifndef __ASSEMBLY__".  Also, what's the impact of
David> adding the the extra check to the fsys_gettimeofday()?  Did you
David> verify that the resulting bundling is still near optimal?

Hi David,

Try this one instead. I guess lazy is my middle name. Anyway I moved
up the relevant defines in sal.h and added the __ASSEMBLY__ test - I
am not going to move it all around as sal.h is absolute mayhem when it
comes to what it tries to include etc.

As for the instruction bundling, yes of course I checked that, how can
you ask ;-) The patch results in a total of three nops before the
branch, however no matter how I move it around, getting rid of those
doesn't seem to be possible (feel free to challenge me on that one).

David> Also, (not in reference to this particular patch): when you
David> send code that calls through a function pointer, I'd really
David> like to see the dereferencing there (for anything that goes in
David> arch/ia64 or include/asm-ia64, I mean).  I know some kernel
David> folks feel differently about this, but it's very misleading to
David> write:

As you wish, I don't feel particularly strongly on this one. I always
hated function pointer definitions, so I guess I just try to make them
look as much as normal functions as I can.

Cheers,
Jes

diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/arch/ia64/kernel/fsys.S linux-2.5.69-030509-timer/arch/ia64/kernel/fsys.S
--- linux-2.5.69-030509-vanilla/arch/ia64/kernel/fsys.S	Sun May  4 19:52:48 2003
+++ linux-2.5.69-030509-timer/arch/ia64/kernel/fsys.S	Mon May 12 21:01:46 2003
@@ -14,6 +14,7 @@
 #include <asm/offsets.h>
 #include <asm/percpu.h>
 #include <asm/thread_info.h>
+#include <asm/sal.h>
 
 /*
  * See Documentation/ia64/fsys.txt for details on fsyscalls.
@@ -142,21 +143,29 @@
  *	   we ought to either skip the ITC-based interpolation or run an ntp-like
  *	   daemon to keep the ITCs from drifting too far apart.
  */
+
 ENTRY(fsys_gettimeofday)
 	add r9=TI_FLAGS+IA64_TASK_SIZE,r16
 	movl r3=THIS_CPU(cpu_info)
 
 	mov.m r31=ar.itc		// put time stamp into r31 (ITC) = now		(35 cyc)
 	movl r19=xtime			// xtime is a timespec struct
+#ifdef CONFIG_SMP
+	movl r2=sal_platform_features
+#endif
 	;;
 
 #ifdef CONFIG_SMP
+	ld8 r2=[r2]
 	movl r10=__per_cpu_offset
 	;;
 	ld8 r10=[r10]			// r10 <- __per_cpu_offset[0]
 	movl r21=cpu_info__per_cpu
+	and r2=IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT,r2
 	;;
 	add r10=r21, r10		// r10 <- &cpu_data(time_keeper_id)
+	cmp.ne p8, p0=0, r2
+(p8)	br.spnt.many fsys_fallback_syscall
 #else
 	mov r10=r3
 #endif
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/arch/ia64/kernel/time.c linux-2.5.69-030509-timer/arch/ia64/kernel/time.c
--- linux-2.5.69-030509-vanilla/arch/ia64/kernel/time.c	Sun May 11 10:53:49 2003
+++ linux-2.5.69-030509-timer/arch/ia64/kernel/time.c	Mon May 12 21:22:37 2003
@@ -17,6 +17,7 @@
 #include <linux/time.h>
 #include <linux/interrupt.h>
 #include <linux/efi.h>
+#include <linux/timex.h>
 
 #include <asm/delay.h>
 #include <asm/hw_irq.h>
@@ -26,9 +27,14 @@
 
 extern unsigned long wall_jiffies;
 extern unsigned long last_nsec_offset;
+static unsigned long __ia64_gettimeoffset (void);
+
+unsigned long (*gettimeoffset)(void) = &__ia64_gettimeoffset;
 
 u64 jiffies_64 = INITIAL_JIFFIES;
 
+#define TIME_KEEPER_ID	0	/* smp_processor_id() of time-keeper */
+
 #ifdef CONFIG_IA64_DEBUG_IRQ
 
 unsigned long last_cli_ip;
@@ -63,15 +69,14 @@
  * Return the number of nano-seconds that elapsed since the last update to jiffy.  The
  * xtime_lock must be at least read-locked when calling this routine.
  */
-static inline unsigned long
-gettimeoffset (void)
+static unsigned long
+__ia64_gettimeoffset (void)
 {
 	unsigned long elapsed_cycles, lost = jiffies - wall_jiffies;
 	unsigned long now, last_tick;
-#	define time_keeper_id	0	/* smp_processor_id() of time-keeper */
 
-	last_tick = (cpu_data(time_keeper_id)->itm_next
-		     - (lost + 1)*cpu_data(time_keeper_id)->itm_delta);
+	last_tick = (cpu_data(TIME_KEEPER_ID)->itm_next
+		     - (lost + 1)*cpu_data(TIME_KEEPER_ID)->itm_delta);
 
 	now = ia64_get_itc();
 	if (unlikely((long) (now - last_tick) < 0)) {
@@ -112,7 +117,7 @@
 		 * Discover what correction gettimeofday would have done, and then undo
 		 * it!
 		 */
-		nsec -= gettimeoffset();
+		nsec -= (*gettimeoffset)();
 
 		wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
 		wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
@@ -124,6 +129,9 @@
 		time_status |= STA_UNSYNC;
 		time_maxerror = NTP_PHASE_LIMIT;
 		time_esterror = NTP_PHASE_LIMIT;
+		if (update_wall_time_hook)
+			(*update_wall_time_hook)();
+
 	}
 	write_sequnlock_irq(&xtime_lock);
 	clock_was_set();
@@ -138,7 +146,7 @@
 		seq = read_seqbegin(&xtime_lock);
 		{
 			old = last_nsec_offset;
-			offset = gettimeoffset();
+			offset = (*gettimeoffset)();
 			sec = xtime.tv_sec;
 			nsec = xtime.tv_nsec;
 		}
@@ -214,7 +222,7 @@
 #endif
 		new_itm += local_cpu_data->itm_delta;
 
-		if (smp_processor_id() = 0) {
+		if (smp_processor_id() = TIME_KEEPER_ID) {
 			/*
 			 * Here we are in the timer irq handler. We have irqs locally
 			 * disabled, but we don't know if the timer_bh is running on
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/arch/ia64/sn/kernel/setup.c linux-2.5.69-030509-timer/arch/ia64/sn/kernel/setup.c
--- linux-2.5.69-030509-vanilla/arch/ia64/sn/kernel/setup.c	Sun May  4 19:53:08 2003
+++ linux-2.5.69-030509-timer/arch/ia64/sn/kernel/setup.c	Sun May 11 14:27:17 2003
@@ -78,9 +78,9 @@
 
 extern void bte_init_node (nodepda_t *, cnodeid_t);
 extern void bte_init_cpu (void);
+extern void sn_timer_init (void);
 
 unsigned long sn_rtc_cycles_per_second;   
-unsigned long sn_rtc_usec_per_cyc;
 
 partid_t sn_partid = -1;
 char sn_system_serial_number_string[128];
@@ -263,13 +263,6 @@
 	else
 		sn_rtc_cycles_per_second = ticks_per_sec;
 
-#ifdef CONFIG_IA64_SGI_SN1
-	/* PROM has wrong value on SN1 */
-	sn_rtc_cycles_per_second = 990177;
-#endif
-	sn_rtc_usec_per_cyc = ((1000000000UL<<IA64_NSEC_PER_CYC_SHIFT)
-			       + sn_rtc_cycles_per_second/2) / sn_rtc_cycles_per_second;
-		
 	for (i=0;i<NR_CPUS;i++)
 		_sn_irq_desc[i] = _irq_desc;
 
@@ -309,6 +302,8 @@
 	 * Turn off "floating-point assist fault" warnings by default.
 	 */
 	current->thread.flags |= IA64_THREAD_FPEMU_NOPRINT;
+
+	sn_timer_init();
 }
 
 /**
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/arch/ia64/sn/kernel/sn2/Makefile linux-2.5.69-030509-timer/arch/ia64/sn/kernel/sn2/Makefile
--- linux-2.5.69-030509-vanilla/arch/ia64/sn/kernel/sn2/Makefile	Sun May  4 19:53:56 2003
+++ linux-2.5.69-030509-timer/arch/ia64/sn/kernel/sn2/Makefile	Sun May 11 14:27:17 2003
@@ -11,4 +11,4 @@
 
 EXTRA_CFLAGS := -DLITTLE_ENDIAN
 
-obj-y += cache.o iomv.o ptc_deadlock.o sn2_smp.o sn_proc_fs.o
+obj-y += cache.o iomv.o ptc_deadlock.o sn2_smp.o sn_proc_fs.o timer.o
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/arch/ia64/sn/kernel/sn2/timer.c linux-2.5.69-030509-timer/arch/ia64/sn/kernel/sn2/timer.c
--- linux-2.5.69-030509-vanilla/arch/ia64/sn/kernel/sn2/timer.c	Wed Dec 31 19:00:00 1969
+++ linux-2.5.69-030509-timer/arch/ia64/sn/kernel/sn2/timer.c	Sun May 11 14:27:17 2003
@@ -0,0 +1,85 @@
+/*
+ * linux/arch/ia64/sn/kernel/sn2/timer.c
+ *
+ * Copyright (C) 2003 Silicon Graphics, Inc.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/time.h>
+#include <linux/interrupt.h>
+
+#include <asm/hw_irq.h>
+#include <asm/system.h>
+
+#include <asm/sn/leds.h>
+#include <asm/sn/clksupport.h>
+
+
+extern unsigned long sn_rtc_cycles_per_second;
+static volatile unsigned long last_wall_rtc;
+
+/**
+ * gettimeoffset - number of nsecs elapsed since &xtime was last updated
+ *
+ * This function is used by do_gettimeofday() to determine the number
+ * of nsecs that have elapsed since the last update to &xtime.  On SN
+ * this is accomplished using the RTC built in to each Hub chip; each
+ * is guaranteed to be synchronized by the PROM, so a local read will
+ * suffice (GET_RTC_COUNTER() does this for us).  A snapshot of the RTC
+ * value is taken every time wall_jiffies is updated by the
+ * update_wall_time_hook (sn2_update_wall_time) which means we don't
+ * have to adjust for lost jiffies ticks or anything like that.
+ */
+
+static volatile long rtc_offset;
+static long rtc_nsecs_per_cycle;
+static long rtc_per_timer_tick;
+
+unsigned long
+sn_gettimeoffset(void)
+{
+	long current_rtc, elapsed_rtc, old, new_offset;
+
+	do {
+		old = rtc_offset;
+		current_rtc = GET_RTC_COUNTER();
+
+		/*
+		 * Need to address wrapping here!
+		 */
+		elapsed_rtc = (long)(current_rtc - last_wall_rtc);
+
+		new_offset = max(elapsed_rtc, old);
+	} while (cmpxchg(&rtc_offset, old, new_offset) != old);
+
+	return new_offset * rtc_nsecs_per_cycle;
+}
+
+
+void sn2_update_wall_time(void)
+{
+	rtc_offset -= min(rtc_offset, rtc_per_timer_tick);
+	last_wall_rtc = GET_RTC_COUNTER();
+}
+
+
+void sn2_reset_wall_time(void)
+{
+	rtc_offset = 0;
+	last_wall_rtc = GET_RTC_COUNTER();
+}
+
+
+void __init
+sn_timer_init(void)
+{
+	rtc_per_timer_tick = sn_rtc_cycles_per_second / HZ;
+	rtc_nsecs_per_cycle = 1000000000 / sn_rtc_cycles_per_second;
+
+	last_wall_rtc = GET_RTC_COUNTER();
+	update_wall_time_hook = sn2_update_wall_time;
+	reset_wall_time_hook = sn2_reset_wall_time;
+	gettimeoffset = sn_gettimeoffset;
+}
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/include/asm-ia64/sal.h linux-2.5.69-030509-timer/include/asm-ia64/sal.h
--- linux-2.5.69-030509-vanilla/include/asm-ia64/sal.h	Sun May 11 10:53:49 2003
+++ linux-2.5.69-030509-timer/include/asm-ia64/sal.h	Mon May 12 21:01:09 2003
@@ -23,6 +23,13 @@
  *                      (plus examples of platform error info structures from smariset @ Intel)
  */
 
+#define IA64_SAL_PLATFORM_FEATURE_BUS_LOCK		(1 << 0)
+#define IA64_SAL_PLATFORM_FEATURE_IRQ_REDIR_HINT	(1 << 1)
+#define IA64_SAL_PLATFORM_FEATURE_IPI_REDIR_HINT	(1 << 2)
+#define IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT	 	(1 << 3)
+
+#ifndef __ASSEMBLY__
+
 #include <linux/spinlock.h>
 #include <linux/efi.h>
 
@@ -162,11 +169,6 @@
 	u8 oem_reserved[8];
 } ia64_sal_desc_memory_t;
 
-#define IA64_SAL_PLATFORM_FEATURE_BUS_LOCK		(1 << 0)
-#define IA64_SAL_PLATFORM_FEATURE_IRQ_REDIR_HINT	(1 << 1)
-#define IA64_SAL_PLATFORM_FEATURE_IPI_REDIR_HINT	(1 << 2)
-#define IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT	 	(1 << 3)
-
 typedef struct ia64_sal_desc_platform_feature {
 	u8 type;
 	u8 feature_mask;
@@ -790,4 +792,6 @@
 
 extern unsigned long sal_platform_features;
 
+#endif /* __ASSEMBLY__ */
+
 #endif /* _ASM_IA64_PAL_H */
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/include/asm-ia64/sn/clksupport.h linux-2.5.69-030509-timer/include/asm-ia64/sn/clksupport.h
--- linux-2.5.69-030509-vanilla/include/asm-ia64/sn/clksupport.h	Sun May  4 19:53:35 2003
+++ linux-2.5.69-030509-timer/include/asm-ia64/sn/clksupport.h	Sun May 11 14:27:17 2003
@@ -38,7 +38,7 @@
 
 extern nasid_t master_nasid;
 
-#define RTC_MASK		(0x007fffffffffffff)
+#define RTC_MASK		0x007fffffffffffffUL
 /* clocks are not synchronized yet on SN1  - used node 0 (problem if no NASID 0) */
 #define RTC_COUNTER_ADDR	((clkreg_t*)REMOTE_HUB_ADDR(master_nasid, PI_RT_COUNTER))
 #define RTC_COMPARE_A_ADDR      ((clkreg_t*)REMOTE_HUB_ADDR(master_nasid, PI_RT_COMPARE_A))
@@ -52,7 +52,7 @@
 #include <asm/sn/sn2/addrs.h>
 #include <asm/sn/sn2/shubio.h>
 #include <asm/sn/sn2/shub_mmr.h>
-#define RTC_MASK		(SH_RTC_MASK)
+#define RTC_MASK		SH_RTC_MASK
 #define RTC_COUNTER_ADDR	((clkreg_t*)LOCAL_MMR_ADDR(SH_RTC))
 #define RTC_COMPARE_A_ADDR      ((clkreg_t*)LOCAL_MMR_ADDR(SH_RTC))
 #define RTC_COMPARE_B_ADDR      ((clkreg_t*)LOCAL_MMR_ADDR(SH_RTC))
@@ -62,7 +62,6 @@
 #define RTC_INT_ENABLED_B_ADDR  ((clkreg_t*)LOCAL_MMR_ADDR(SH_RTC))
 #endif	/* CONFIG_IA64_SGI_SN1 */
 
-
 #define GET_RTC_COUNTER()	(*RTC_COUNTER_ADDR)
 #define rtc_time()		GET_RTC_COUNTER()
 
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/include/asm-ia64/timex.h linux-2.5.69-030509-timer/include/asm-ia64/timex.h
--- linux-2.5.69-030509-vanilla/include/asm-ia64/timex.h	Sun May  4 19:53:40 2003
+++ linux-2.5.69-030509-timer/include/asm-ia64/timex.h	Sun May 11 14:27:17 2003
@@ -25,4 +25,6 @@
 	return ret;
 }
 
+extern unsigned long (*gettimeoffset)(void);
+
 #endif /* _ASM_IA64_TIMEX_H */
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/include/linux/timex.h linux-2.5.69-030509-timer/include/linux/timex.h
--- linux-2.5.69-030509-vanilla/include/linux/timex.h	Sun May  4 19:52:59 2003
+++ linux-2.5.69-030509-timer/include/linux/timex.h	Sun May 11 14:27:17 2003
@@ -310,6 +310,13 @@
 extern long pps_errcnt;		/* calibration errors */
 extern long pps_stbcnt;		/* stability limit exceeded */
 
+/*
+ * Call-back for high precision timer sources to snapshot every time
+ * wall_jiffies is updated.
+ */
+extern void (*update_wall_time_hook)(void);
+extern void (*reset_wall_time_hook)(void);
+
 #endif /* KERNEL */
 
 #endif /* LINUX_TIMEX_H */
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/kernel/time.c linux-2.5.69-030509-timer/kernel/time.c
--- linux-2.5.69-030509-vanilla/kernel/time.c	Sun May 11 10:53:49 2003
+++ linux-2.5.69-030509-timer/kernel/time.c	Mon May 12 20:53:32 2003
@@ -77,6 +77,9 @@
 	if (get_user(value, tptr))
 		return -EFAULT;
 	write_seqlock_irq(&xtime_lock);
+
+	if (reset_wall_time_hook)
+		(*reset_wall_time_hook)();
 	xtime.tv_sec = value;
 	xtime.tv_nsec = 0;
 	last_nsec_offset = 0;
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/kernel/timer.c linux-2.5.69-030509-timer/kernel/timer.c
--- linux-2.5.69-030509-vanilla/kernel/timer.c	Sun May 11 10:53:49 2003
+++ linux-2.5.69-030509-timer/kernel/timer.c	Mon May 12 20:52:43 2003
@@ -665,6 +665,15 @@
 }
 
 /*
+ * Hook for using external high precision timers for the system clock.
+ * On systems where the CPU clock isn't synchronized between CPUs,
+ * it is necessary to use an external source such as an RTC to obtain
+ * precision in gettimeofday().
+ */
+void (*update_wall_time_hook)(void);
+void (*reset_wall_time_hook)(void);
+
+/*
  * Using a loop looks inefficient, but "ticks" is
  * usually just one (we shouldn't be losing ticks,
  * we're doing this this way mainly for interrupt
@@ -676,12 +685,17 @@
 	do {
 		ticks--;
 		update_wall_time_one_tick();
+
+		if (update_wall_time_hook)
+			(*update_wall_time_hook)();
 	} while (ticks);
 
 	if (xtime.tv_nsec >= 1000000000) {
 	    xtime.tv_nsec -= 1000000000;
 	    xtime.tv_sec++;
 	    second_overflow();
+	    if (update_wall_time_hook)
+		    (*update_wall_time_hook)();
 	}
 }
 

Re: [Linux-ia64] gettimeoffset for 2.5.67

[David Mosberger]

>>>>> On 12 May 2003 22:05:02 -0400, Jes Sorensen <jes@wildopensource.com> said:

  Jes> As for the instruction bundling, yes of course I checked that, how can
  Jes> you ask ;-) The patch results in a total of three nops before the
  Jes> branch, however no matter how I move it around, getting rid of those
  Jes> doesn't seem to be possible (feel free to challenge me on that one).

This:

+	and r2=IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT,r2
 	;;
+	cmp.ne p8, p0=0, r2
+(p8)	br.spnt.many fsys_fallback_syscall


can be shortened to:

	tbit.nz p8, p0=IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT_BIT, r2
(p8)	br.spnt.many fsys_fallback_syscall

Might make it a bit easier to schedule things around (just add foo_BIT
numbers for all the SAL_PLATFORM_FEATURE bits and then define the
masks in terms of these bit numbers).

Sorry I didn't catch this previously.

	--david

Re: [Linux-ia64] gettimeoffset for 2.5.67

[Jes Sorensen]

>>>>> "David" = David Mosberger <davidm@napali.hpl.hp.com> writes:

David> Might make it a bit easier to schedule things around (just add
David> foo_BIT numbers for all the SAL_PLATFORM_FEATURE bits and then
David> define the masks in terms of these bit numbers).

David> Sorry I didn't catch this previously.

Now try this!

Today we proudly present to you: gettimeoffset() du jour, the most
beautiful version of gettimeoffset() ever written! With enhanced bit
mangling and fewer stop bits for your exclusive timing pleasure!

Cheers,
Jes

diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/arch/ia64/kernel/fsys.S linux-2.5.69-030509-timer/arch/ia64/kernel/fsys.S
--- linux-2.5.69-030509-vanilla/arch/ia64/kernel/fsys.S	Sun May  4 19:52:48 2003
+++ linux-2.5.69-030509-timer/arch/ia64/kernel/fsys.S	Tue May 13 11:28:53 2003
@@ -14,6 +14,7 @@
 #include <asm/offsets.h>
 #include <asm/percpu.h>
 #include <asm/thread_info.h>
+#include <asm/sal.h>
 
 /*
  * See Documentation/ia64/fsys.txt for details on fsyscalls.
@@ -142,23 +143,30 @@
  *	   we ought to either skip the ITC-based interpolation or run an ntp-like
  *	   daemon to keep the ITCs from drifting too far apart.
  */
+
 ENTRY(fsys_gettimeofday)
 	add r9=TI_FLAGS+IA64_TASK_SIZE,r16
 	movl r3=THIS_CPU(cpu_info)
 
 	mov.m r31=ar.itc		// put time stamp into r31 (ITC) = now		(35 cyc)
-	movl r19=xtime			// xtime is a timespec struct
-	;;
-
 #ifdef CONFIG_SMP
 	movl r10=__per_cpu_offset
+	movl r2=sal_platform_features
 	;;
+
+	ld8 r2=[r2]
+	movl r19=xtime			// xtime is a timespec struct
+
 	ld8 r10=[r10]			// r10 <- __per_cpu_offset[0]
 	movl r21=cpu_info__per_cpu
 	;;
 	add r10=r21, r10		// r10 <- &cpu_data(time_keeper_id)
+	tbit.nz p8,p0 = r2, IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT_BIT
+(p8)	br.spnt.many fsys_fallback_syscall
 #else
+	;;
 	mov r10=r3
+	movl r19=xtime			// xtime is a timespec struct
 #endif
 	ld4 r9=[r9]
 	movl r17=xtime_lock
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/arch/ia64/kernel/time.c linux-2.5.69-030509-timer/arch/ia64/kernel/time.c
--- linux-2.5.69-030509-vanilla/arch/ia64/kernel/time.c	Sun May 11 10:53:49 2003
+++ linux-2.5.69-030509-timer/arch/ia64/kernel/time.c	Mon May 12 21:22:37 2003
@@ -17,6 +17,7 @@
 #include <linux/time.h>
 #include <linux/interrupt.h>
 #include <linux/efi.h>
+#include <linux/timex.h>
 
 #include <asm/delay.h>
 #include <asm/hw_irq.h>
@@ -26,9 +27,14 @@
 
 extern unsigned long wall_jiffies;
 extern unsigned long last_nsec_offset;
+static unsigned long __ia64_gettimeoffset (void);
+
+unsigned long (*gettimeoffset)(void) = &__ia64_gettimeoffset;
 
 u64 jiffies_64 = INITIAL_JIFFIES;
 
+#define TIME_KEEPER_ID	0	/* smp_processor_id() of time-keeper */
+
 #ifdef CONFIG_IA64_DEBUG_IRQ
 
 unsigned long last_cli_ip;
@@ -63,15 +69,14 @@
  * Return the number of nano-seconds that elapsed since the last update to jiffy.  The
  * xtime_lock must be at least read-locked when calling this routine.
  */
-static inline unsigned long
-gettimeoffset (void)
+static unsigned long
+__ia64_gettimeoffset (void)
 {
 	unsigned long elapsed_cycles, lost = jiffies - wall_jiffies;
 	unsigned long now, last_tick;
-#	define time_keeper_id	0	/* smp_processor_id() of time-keeper */
 
-	last_tick = (cpu_data(time_keeper_id)->itm_next
-		     - (lost + 1)*cpu_data(time_keeper_id)->itm_delta);
+	last_tick = (cpu_data(TIME_KEEPER_ID)->itm_next
+		     - (lost + 1)*cpu_data(TIME_KEEPER_ID)->itm_delta);
 
 	now = ia64_get_itc();
 	if (unlikely((long) (now - last_tick) < 0)) {
@@ -112,7 +117,7 @@
 		 * Discover what correction gettimeofday would have done, and then undo
 		 * it!
 		 */
-		nsec -= gettimeoffset();
+		nsec -= (*gettimeoffset)();
 
 		wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
 		wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
@@ -124,6 +129,9 @@
 		time_status |= STA_UNSYNC;
 		time_maxerror = NTP_PHASE_LIMIT;
 		time_esterror = NTP_PHASE_LIMIT;
+		if (update_wall_time_hook)
+			(*update_wall_time_hook)();
+
 	}
 	write_sequnlock_irq(&xtime_lock);
 	clock_was_set();
@@ -138,7 +146,7 @@
 		seq = read_seqbegin(&xtime_lock);
 		{
 			old = last_nsec_offset;
-			offset = gettimeoffset();
+			offset = (*gettimeoffset)();
 			sec = xtime.tv_sec;
 			nsec = xtime.tv_nsec;
 		}
@@ -214,7 +222,7 @@
 #endif
 		new_itm += local_cpu_data->itm_delta;
 
-		if (smp_processor_id() = 0) {
+		if (smp_processor_id() = TIME_KEEPER_ID) {
 			/*
 			 * Here we are in the timer irq handler. We have irqs locally
 			 * disabled, but we don't know if the timer_bh is running on
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/arch/ia64/sn/kernel/setup.c linux-2.5.69-030509-timer/arch/ia64/sn/kernel/setup.c
--- linux-2.5.69-030509-vanilla/arch/ia64/sn/kernel/setup.c	Sun May  4 19:53:08 2003
+++ linux-2.5.69-030509-timer/arch/ia64/sn/kernel/setup.c	Sun May 11 14:27:17 2003
@@ -78,9 +78,9 @@
 
 extern void bte_init_node (nodepda_t *, cnodeid_t);
 extern void bte_init_cpu (void);
+extern void sn_timer_init (void);
 
 unsigned long sn_rtc_cycles_per_second;   
-unsigned long sn_rtc_usec_per_cyc;
 
 partid_t sn_partid = -1;
 char sn_system_serial_number_string[128];
@@ -263,13 +263,6 @@
 	else
 		sn_rtc_cycles_per_second = ticks_per_sec;
 
-#ifdef CONFIG_IA64_SGI_SN1
-	/* PROM has wrong value on SN1 */
-	sn_rtc_cycles_per_second = 990177;
-#endif
-	sn_rtc_usec_per_cyc = ((1000000000UL<<IA64_NSEC_PER_CYC_SHIFT)
-			       + sn_rtc_cycles_per_second/2) / sn_rtc_cycles_per_second;
-		
 	for (i=0;i<NR_CPUS;i++)
 		_sn_irq_desc[i] = _irq_desc;
 
@@ -309,6 +302,8 @@
 	 * Turn off "floating-point assist fault" warnings by default.
 	 */
 	current->thread.flags |= IA64_THREAD_FPEMU_NOPRINT;
+
+	sn_timer_init();
 }
 
 /**
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/arch/ia64/sn/kernel/sn2/Makefile linux-2.5.69-030509-timer/arch/ia64/sn/kernel/sn2/Makefile
--- linux-2.5.69-030509-vanilla/arch/ia64/sn/kernel/sn2/Makefile	Sun May  4 19:53:56 2003
+++ linux-2.5.69-030509-timer/arch/ia64/sn/kernel/sn2/Makefile	Sun May 11 14:27:17 2003
@@ -11,4 +11,4 @@
 
 EXTRA_CFLAGS := -DLITTLE_ENDIAN
 
-obj-y += cache.o iomv.o ptc_deadlock.o sn2_smp.o sn_proc_fs.o
+obj-y += cache.o iomv.o ptc_deadlock.o sn2_smp.o sn_proc_fs.o timer.o
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/arch/ia64/sn/kernel/sn2/timer.c linux-2.5.69-030509-timer/arch/ia64/sn/kernel/sn2/timer.c
--- linux-2.5.69-030509-vanilla/arch/ia64/sn/kernel/sn2/timer.c	Wed Dec 31 19:00:00 1969
+++ linux-2.5.69-030509-timer/arch/ia64/sn/kernel/sn2/timer.c	Sun May 11 14:27:17 2003
@@ -0,0 +1,85 @@
+/*
+ * linux/arch/ia64/sn/kernel/sn2/timer.c
+ *
+ * Copyright (C) 2003 Silicon Graphics, Inc.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/time.h>
+#include <linux/interrupt.h>
+
+#include <asm/hw_irq.h>
+#include <asm/system.h>
+
+#include <asm/sn/leds.h>
+#include <asm/sn/clksupport.h>
+
+
+extern unsigned long sn_rtc_cycles_per_second;
+static volatile unsigned long last_wall_rtc;
+
+/**
+ * gettimeoffset - number of nsecs elapsed since &xtime was last updated
+ *
+ * This function is used by do_gettimeofday() to determine the number
+ * of nsecs that have elapsed since the last update to &xtime.  On SN
+ * this is accomplished using the RTC built in to each Hub chip; each
+ * is guaranteed to be synchronized by the PROM, so a local read will
+ * suffice (GET_RTC_COUNTER() does this for us).  A snapshot of the RTC
+ * value is taken every time wall_jiffies is updated by the
+ * update_wall_time_hook (sn2_update_wall_time) which means we don't
+ * have to adjust for lost jiffies ticks or anything like that.
+ */
+
+static volatile long rtc_offset;
+static long rtc_nsecs_per_cycle;
+static long rtc_per_timer_tick;
+
+unsigned long
+sn_gettimeoffset(void)
+{
+	long current_rtc, elapsed_rtc, old, new_offset;
+
+	do {
+		old = rtc_offset;
+		current_rtc = GET_RTC_COUNTER();
+
+		/*
+		 * Need to address wrapping here!
+		 */
+		elapsed_rtc = (long)(current_rtc - last_wall_rtc);
+
+		new_offset = max(elapsed_rtc, old);
+	} while (cmpxchg(&rtc_offset, old, new_offset) != old);
+
+	return new_offset * rtc_nsecs_per_cycle;
+}
+
+
+void sn2_update_wall_time(void)
+{
+	rtc_offset -= min(rtc_offset, rtc_per_timer_tick);
+	last_wall_rtc = GET_RTC_COUNTER();
+}
+
+
+void sn2_reset_wall_time(void)
+{
+	rtc_offset = 0;
+	last_wall_rtc = GET_RTC_COUNTER();
+}
+
+
+void __init
+sn_timer_init(void)
+{
+	rtc_per_timer_tick = sn_rtc_cycles_per_second / HZ;
+	rtc_nsecs_per_cycle = 1000000000 / sn_rtc_cycles_per_second;
+
+	last_wall_rtc = GET_RTC_COUNTER();
+	update_wall_time_hook = sn2_update_wall_time;
+	reset_wall_time_hook = sn2_reset_wall_time;
+	gettimeoffset = sn_gettimeoffset;
+}
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/include/asm-ia64/sal.h linux-2.5.69-030509-timer/include/asm-ia64/sal.h
--- linux-2.5.69-030509-vanilla/include/asm-ia64/sal.h	Sun May 11 10:53:49 2003
+++ linux-2.5.69-030509-timer/include/asm-ia64/sal.h	Tue May 13 10:47:02 2003
@@ -23,6 +23,18 @@
  *                      (plus examples of platform error info structures from smariset @ Intel)
  */
 
+#define IA64_SAL_PLATFORM_FEATURE_BUS_LOCK		(1 << 0)
+#define IA64_SAL_PLATFORM_FEATURE_IRQ_REDIR_HINT	(1 << 1)
+#define IA64_SAL_PLATFORM_FEATURE_IPI_REDIR_HINT	(1 << 2)
+#define IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT	 	(1 << 3)
+
+#define IA64_SAL_PLATFORM_FEATURE_BUS_LOCK_BIT		0
+#define IA64_SAL_PLATFORM_FEATURE_IRQ_REDIR_HINT_BIT	1
+#define IA64_SAL_PLATFORM_FEATURE_IPI_REDIR_HINT_BIT	2
+#define IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT_BIT	 	3
+
+#ifndef __ASSEMBLY__
+
 #include <linux/spinlock.h>
 #include <linux/efi.h>
 
@@ -162,11 +174,6 @@
 	u8 oem_reserved[8];
 } ia64_sal_desc_memory_t;
 
-#define IA64_SAL_PLATFORM_FEATURE_BUS_LOCK		(1 << 0)
-#define IA64_SAL_PLATFORM_FEATURE_IRQ_REDIR_HINT	(1 << 1)
-#define IA64_SAL_PLATFORM_FEATURE_IPI_REDIR_HINT	(1 << 2)
-#define IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT	 	(1 << 3)
-
 typedef struct ia64_sal_desc_platform_feature {
 	u8 type;
 	u8 feature_mask;
@@ -790,4 +797,6 @@
 
 extern unsigned long sal_platform_features;
 
+#endif /* __ASSEMBLY__ */
+
 #endif /* _ASM_IA64_PAL_H */
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/include/asm-ia64/sn/clksupport.h linux-2.5.69-030509-timer/include/asm-ia64/sn/clksupport.h
--- linux-2.5.69-030509-vanilla/include/asm-ia64/sn/clksupport.h	Sun May  4 19:53:35 2003
+++ linux-2.5.69-030509-timer/include/asm-ia64/sn/clksupport.h	Sun May 11 14:27:17 2003
@@ -38,7 +38,7 @@
 
 extern nasid_t master_nasid;
 
-#define RTC_MASK		(0x007fffffffffffff)
+#define RTC_MASK		0x007fffffffffffffUL
 /* clocks are not synchronized yet on SN1  - used node 0 (problem if no NASID 0) */
 #define RTC_COUNTER_ADDR	((clkreg_t*)REMOTE_HUB_ADDR(master_nasid, PI_RT_COUNTER))
 #define RTC_COMPARE_A_ADDR      ((clkreg_t*)REMOTE_HUB_ADDR(master_nasid, PI_RT_COMPARE_A))
@@ -52,7 +52,7 @@
 #include <asm/sn/sn2/addrs.h>
 #include <asm/sn/sn2/shubio.h>
 #include <asm/sn/sn2/shub_mmr.h>
-#define RTC_MASK		(SH_RTC_MASK)
+#define RTC_MASK		SH_RTC_MASK
 #define RTC_COUNTER_ADDR	((clkreg_t*)LOCAL_MMR_ADDR(SH_RTC))
 #define RTC_COMPARE_A_ADDR      ((clkreg_t*)LOCAL_MMR_ADDR(SH_RTC))
 #define RTC_COMPARE_B_ADDR      ((clkreg_t*)LOCAL_MMR_ADDR(SH_RTC))
@@ -62,7 +62,6 @@
 #define RTC_INT_ENABLED_B_ADDR  ((clkreg_t*)LOCAL_MMR_ADDR(SH_RTC))
 #endif	/* CONFIG_IA64_SGI_SN1 */
 
-
 #define GET_RTC_COUNTER()	(*RTC_COUNTER_ADDR)
 #define rtc_time()		GET_RTC_COUNTER()
 
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/include/asm-ia64/timex.h linux-2.5.69-030509-timer/include/asm-ia64/timex.h
--- linux-2.5.69-030509-vanilla/include/asm-ia64/timex.h	Sun May  4 19:53:40 2003
+++ linux-2.5.69-030509-timer/include/asm-ia64/timex.h	Sun May 11 14:27:17 2003
@@ -25,4 +25,6 @@
 	return ret;
 }
 
+extern unsigned long (*gettimeoffset)(void);
+
 #endif /* _ASM_IA64_TIMEX_H */
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/include/linux/timex.h linux-2.5.69-030509-timer/include/linux/timex.h
--- linux-2.5.69-030509-vanilla/include/linux/timex.h	Sun May  4 19:52:59 2003
+++ linux-2.5.69-030509-timer/include/linux/timex.h	Sun May 11 14:27:17 2003
@@ -310,6 +310,13 @@
 extern long pps_errcnt;		/* calibration errors */
 extern long pps_stbcnt;		/* stability limit exceeded */
 
+/*
+ * Call-back for high precision timer sources to snapshot every time
+ * wall_jiffies is updated.
+ */
+extern void (*update_wall_time_hook)(void);
+extern void (*reset_wall_time_hook)(void);
+
 #endif /* KERNEL */
 
 #endif /* LINUX_TIMEX_H */
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/kernel/time.c linux-2.5.69-030509-timer/kernel/time.c
--- linux-2.5.69-030509-vanilla/kernel/time.c	Sun May 11 10:53:49 2003
+++ linux-2.5.69-030509-timer/kernel/time.c	Mon May 12 20:53:32 2003
@@ -77,6 +77,9 @@
 	if (get_user(value, tptr))
 		return -EFAULT;
 	write_seqlock_irq(&xtime_lock);
+
+	if (reset_wall_time_hook)
+		(*reset_wall_time_hook)();
 	xtime.tv_sec = value;
 	xtime.tv_nsec = 0;
 	last_nsec_offset = 0;
diff -urN -X /home/jes/exclude-linux linux-2.5.69-030509-vanilla/kernel/timer.c linux-2.5.69-030509-timer/kernel/timer.c
--- linux-2.5.69-030509-vanilla/kernel/timer.c	Sun May 11 10:53:49 2003
+++ linux-2.5.69-030509-timer/kernel/timer.c	Mon May 12 20:52:43 2003
@@ -665,6 +665,15 @@
 }
 
 /*
+ * Hook for using external high precision timers for the system clock.
+ * On systems where the CPU clock isn't synchronized between CPUs,
+ * it is necessary to use an external source such as an RTC to obtain
+ * precision in gettimeofday().
+ */
+void (*update_wall_time_hook)(void);
+void (*reset_wall_time_hook)(void);
+
+/*
  * Using a loop looks inefficient, but "ticks" is
  * usually just one (we shouldn't be losing ticks,
  * we're doing this this way mainly for interrupt
@@ -676,12 +685,17 @@
 	do {
 		ticks--;
 		update_wall_time_one_tick();
+
+		if (update_wall_time_hook)
+			(*update_wall_time_hook)();
 	} while (ticks);
 
 	if (xtime.tv_nsec >= 1000000000) {
 	    xtime.tv_nsec -= 1000000000;
 	    xtime.tv_sec++;
 	    second_overflow();
+	    if (update_wall_time_hook)
+		    (*update_wall_time_hook)();
 	}
 }
 

Re: [Linux-ia64] gettimeoffset for 2.5.67

[David Mosberger]

>>>>> On 13 May 2003 11:42:43 -0400, Jes Sorensen <jes@wildopensource.com> said:

  Jes> Today we proudly present to you: gettimeoffset() du jour, the
  Jes> most beautiful version of gettimeoffset() ever written! With
  Jes> enhanced bit mangling and fewer stop bits for your exclusive
  Jes> timing pleasure!

Now you're getting into the spirit! ;-)

The patch looks pretty good to me.  I'll try it soon (hopefully
today).

Thanks for your patience.

	--david