%patch
Index: linux-2.6.7/arch/ia64/kernel/cyclone.c
===================================================================
--- linux-2.6.7.orig/arch/ia64/kernel/cyclone.c
+++ linux-2.6.7/arch/ia64/kernel/cyclone.c
@@ -16,62 +16,10 @@
 	return 1;
 }
 
-static u32* volatile cyclone_timer;	/* Cyclone MPMC0 register */
-static u32 last_update_cyclone;
-
-static unsigned long offset_base;
-
-static unsigned long get_offset_cyclone(void)
-{
-	u32 now;
-	unsigned long offset;
-
-	/* Read the cyclone timer */
-	now = readl(cyclone_timer);
-	/* .. relative to previous update*/
-	offset = now - last_update_cyclone;
-
-	/* convert cyclone ticks to nanoseconds */
-	offset = (offset*NSEC_PER_SEC)/CYCLONE_TIMER_FREQ;
-
-	/* our adjusted time in nanoseconds */
-	return offset_base + offset;
-}
-
-static void update_cyclone(long delta_nsec)
-{
-	u32 now;
-	unsigned long offset;
-
-	/* Read the cyclone timer */
-	now = readl(cyclone_timer);
-	/* .. relative to previous update*/
-	offset = now - last_update_cyclone;
-
-	/* convert cyclone ticks to nanoseconds */
-	offset = (offset*NSEC_PER_SEC)/CYCLONE_TIMER_FREQ;
-
-	offset += offset_base;
-
-	/* Be careful about signed/unsigned comparisons here: */
-	if (delta_nsec < 0 || (unsigned long) delta_nsec < offset)
-		offset_base = offset - delta_nsec;
-	else
-		offset_base = 0;
-
-	last_update_cyclone = now;
-}
-
-static void reset_cyclone(void)
-{
-	offset_base = 0;
-	last_update_cyclone = readl(cyclone_timer);
-}
 
 struct time_interpolator cyclone_interpolator = {
-	.get_offset =	get_offset_cyclone,
-	.update =	update_cyclone,
-	.reset =	reset_cyclone,
+	.source =	TIME_SOURCE_MMIO32,
+	.shift =	32,
 	.frequency =	CYCLONE_TIMER_FREQ,
 	.drift =	-100,
 };
@@ -82,6 +30,7 @@
 	u64 base;	/* saved cyclone base address */
 	u64 offset;	/* offset from pageaddr to cyclone_timer register */
 	int i;
+	u32* volatile cyclone_timer;	/* Cyclone MPMC0 register */
 
 	if (!use_cyclone)
 		return -ENODEV;
@@ -149,7 +98,7 @@
 		}
 	}
 	/* initialize last tick */
-	last_update_cyclone = readl(cyclone_timer);
+	cyclone_interpolator.addr = cyclone_timer;
 	register_time_interpolator(&cyclone_interpolator);
 
 	return 0;
Index: linux-2.6.7/arch/ia64/kernel/fsys.S
===================================================================
--- linux-2.6.7.orig/arch/ia64/kernel/fsys.S
+++ linux-2.6.7/arch/ia64/kernel/fsys.S
@@ -8,6 +8,8 @@
  * 18-Feb-03 louisk	Implement fsys_gettimeofday().
  * 28-Feb-03 davidm	Fixed several bugs in fsys_gettimeofday().  Tuned it some more,
  *			probably broke it along the way... ;-)
+ * 13-Jul-04 clameter   Implement fsys_clock_gettime and revise fsys_gettimeofday to make
+ *                      it capable of using memory based clocks without falling back to C code.
  */
 
 #include <asm/asmmacro.h>
@@ -144,195 +146,181 @@
 END(fsys_set_tid_address)
 
 /*
- * Note 1: This routine uses floating-point registers, but only with registers that
- *	   operate on integers.  Because of that, we don't need to set ar.fpsr to the
- *	   kernel default value.
- *
- * Note 2: For now, we will assume that all CPUs run at the same clock-frequency.
- *	   If that wasn't the case, we would have to disable preemption (e.g.,
- *	   by disabling interrupts) between reading the ITC and reading
- *	   local_cpu_data->nsec_per_cyc.
- *
- * Note 3: On platforms where the ITC-drift bit is set in the SAL feature vector,
- *	   we ought to either skip the ITC-based interpolation or run an ntp-like
- *	   daemon to keep the ITCs from drifting too far apart.
+ * Ensure that the time interpolator structure is compatible with the asm code
  */
-
+#if IA64_TIME_INTERPOLATOR_SOURCE_OFFSET !=0 || IA64_TIME_INTERPOLATOR_SHIFT_OFFSET != 2 \
+	|| IA64_TIME_INTERPOLATOR_NSEC_OFFSET != 4
+#error fsys_gettimeofday incompatible with changes to struct time_interpolator
+#endif
+#define CLOCK_REALTIME 0
+#define CLOCK_MONOTONIC 1
+#define CLOCK_DIVIDE_BY_1000 0x4000
+#define CLOCK_ADD_MONOTONIC 0x8000
 ENTRY(fsys_gettimeofday)
 	.prologue
 	.altrp b6
 	.body
-	add r9=TI_FLAGS+IA64_TASK_SIZE,r16
-	addl r3=THIS_CPU(cpu_info),r0
-
-#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]
-	addl r21=THIS_CPU(cpu_info),r0
-	;;
-	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
-	;;
-
-	// r32, r33 should contain the 2 args of gettimeofday
-	adds r21=IA64_CPUINFO_ITM_NEXT_OFFSET, r10
-	mov r2=-1
-	tnat.nz p6,p7=r32		// guard against NaT args
-	;;
-
-	adds r10=IA64_CPUINFO_ITM_DELTA_OFFSET, r10
-(p7)	tnat.nz p6,p0=r33
-(p6)	br.cond.spnt.few .fail_einval
-
-	adds r8=IA64_CPUINFO_NSEC_PER_CYC_OFFSET, r3
-	movl r24=2361183241434822607	// for division hack (only for / 1000)
-	;;
-
-	ldf8 f7=[r10]			// f7 now contains itm_delta
-	setf.sig f11=r2
-	adds r10=8, r32
-
-	adds r20=IA64_TIMESPEC_TV_NSEC_OFFSET, r19	// r20 = &xtime->tv_nsec
-	movl r26=jiffies
-
-	setf.sig f9=r24			// f9 is used for division hack
-	movl r27=wall_jiffies
-
-	and r9=TIF_ALLWORK_MASK,r9
-	movl r25=last_nsec_offset
-	;;
-
-	/*
-	 * Verify that we have permission to write to struct timeval.  Note:
-	 * Another thread might unmap the mapping before we actually get
-	 * to store the result.  That's OK as long as the stores are also
-	 * protect by EX().
-	 */
-EX(.fail_efault, probe.w.fault r32, 3)		// this must come _after_ NaT-check
-EX(.fail_efault, probe.w.fault r10, 3)		// this must come _after_ NaT-check
-	nop 0
-
-	ldf8 f10=[r8]			// f10 <- local_cpu_data->nsec_per_cyc value
-	cmp.ne p8, p0=0, r9
-(p8)	br.spnt.many fsys_fallback_syscall
-	;;
-.retry:	// *** seq = read_seqbegin(&xtime_lock); ***
-	ld4.acq r23=[r17]		// since &xtime_lock == &xtime_lock->sequence
-	ld8 r14=[r25]			// r14 (old) = last_nsec_offset
-
-	ld8 r28=[r26]			// r28 = jiffies
-	ld8 r29=[r27]			// r29 = wall_jiffies
+	mov r27 = r32
+	mov r26 = CLOCK_DIVIDE_BY_1000
+	tnat.nz p6,p0 = r33		// guard against NaT argument
+(p6)    br.cond.spnt.few .fail_einval
+	;;
+.gettime:
+	// Register map
+	// Not touched >=r32 and other reserved registers
+	// Incoming r27 = pointer to address where to place result
+	//          r26 = flags determining how time is processed
+	// r2,3 = temp
+	// r8 = temporary storage for last itc value
+	// r10 = temporary storage for clock difference
+	// r20 = initial sequence number
+	// r21 = result seconds
+	// r22 = result nanoseconds
+	// r23 = time interpolator first quad with sourcetype, shift, nsec_per_cyc
+	// r24 = time interpolator_last_counter
+	// r25 = address of time_interpolator_last_cycle
+	// r26 = time processing flags
+	// r27 = pointer to sec portion 
+	// r28 = pointer to nsec portion of argument (r32+8)
+	// r29 = address of wall_to_monotonic
+	// r30 = pointer to struct time_interpolator
+	// r31 = address of seqlock
+	// Predicates
+	// p6,p7 short term use
+	// p8 = timesource ar.itc
+	// p9 = timesource mmio64
+	// p10 = timesource mmio32
+	// p11 = timesource not to be handled by asm code
+	// p12 = unused
+	// p13 = do cmpxchg with time_interpolator_last_cycle
+	// p14 = Divide by 1000
+	// p15 = Add monotonic
+	mov pr = r26,0xc000
+	tnat.nz p6,p0 = r27
+(p6)    br.cond.spnt.few .fail_einval
+	add r2 = TI_FLAGS+IA64_TASK_SIZE,r16
+	add r28 = IA64_TIMESPEC_TV_NSEC_OFFSET,r27
+	movl r30 = time_interpolator
+	movl r31 = xtime_lock
+	movl r21 = xtime
+	;;
+EX(.fail_efault, probe.w.fault r27, 3)
+EX(.fail_efault, probe.w.fault r28, 3)
+	ld8 r30 = [r30]			// now pointer to time_interpolator
+	ld4 r2 = [r2]
+	add r22 = IA64_TIMESPEC_TV_NSEC_OFFSET,r21
+	;;
+	and r2 = TIF_ALLWORK_MASK,r2
+	ld8 r3 = [r30]
+	add r24 = IA64_TIME_INTERPOLATOR_LAST_COUNTER_OFFSET,r30
+	;;
+	cmp.ne p6, p0 = 0, r2	// Fallback if work is scheduled
+(p6)    br.cond.spnt.many fsys_fallback_syscall
+	mov pr = r3,0x3f00	// Set up predicate for timer operations
+	;;
+(p11)	br.cond.spnt.many fsys_fallback_syscall		// timer source is C function
+	extr r23 = r3,16,16	// time_interpolator->shift
+	extr r3 = r3,32,32	// time_interpolator->nsec_per_cyc
+	add r2 = IA64_TIME_INTERPOLATOR_ADDRESS_OFFSET,r30
+(p15)	movl r29 = wall_to_monotonic
+(p13)	add r25 = IA64_TIME_INTERPOLATOR_LAST_CYCLE_OFFSET,r30
+	;;
+	setf.sig f7 = r3
+	ld8 r2 = [r2]
+	ld4.acq r20 = [r31]	//  xtime_lock.sequence
+	;;
+	// Start critical section
+	.pred.rel.mutex p8,p9,p10
+	ld8 r24 = [r24]		// time_interpolator_last_counter
+ 	ld8 r21 = [r21]		// xtime.tv_sec
+	ld8 r22 = [r22]		// xtime.tv_nsec
+(p15)	ld8 r3 = [r29],8	// wall_to_monotonic.sec
+(p13)	ld8 r8 = [r25]		// time interpolator last_cycle
+(p9)	ld8 r2 = [r2]		// readq(ti->address)
+(p10)	ld4 r2 = [r2]		// readw(ti->address)
+(p8)	mov r2 = ar.itc		// CPU_TIMER
+	;;
+(p15)	add r21 = r21,r3	// Add monotonic.secs to secs
+(p13)	cmp.gt.unc p6,p13 = r8,r2	// check if it is less than last. p6,p13 cleared
+(p15)	ld8 r29 = [r29]		// wall_to_monotonic.nsecs
+	;;
+(p6)	mov r2 = r8		// time we got was less than last_cycle
+(p13)	mov ar.ccv = r8		// more than last_cycle. Prep for cmpxchg
+	;;
+(p13)	cmpxchg8.rel r25 = [r25],r2,ar.ccv
+	sub r10 = r2, r24	// current_counter - last_counter
+	add r3 = IA64_TIME_INTERPOLATOR_OFFSET_OFFSET,r30
+	;;
+(p13)	cmp.ne p13,p0 = r8,r25	// if cmpxchg not successful redo
+(p13)	br.cond.dpnt.few .gettime 
+	setf.sig f8 = r10
+(p15)	add r22 = r22,r29	// Add monotonic.nsecs to nsecs
+	ld8 r3 = [r3]		// time_interpolator_offset
 	;;
-
-	ldf8 f8=[r21]			// f8 now contains itm_next
-	mov.m r31=ar.itc		// put time stamp into r31 (ITC) == now
-	sub r28=r29, r28, 1		// r28 now contains "-(lost + 1)"
+	xmpy.l f8 = f8,f7	// nsec_per_cyc*(counter-last_counter)
+	add r22 = r22,r3	// Add time interpolator offset
 	;;
-
-	ld8 r2=[r19]			// r2 = sec = xtime.tv_sec
-	ld8 r29=[r20]			// r29 = nsec = xtime.tv_nsec
-	tbit.nz p9, p10=r23, 0		// p9 <- is_odd(r23), p10 <- is_even(r23)
-
-	setf.sig f6=r28			// f6 <- -(lost + 1)				(6 cyc)
+	getf.sig r2 = f8
+	and r20 = ~1,r20	// Make sequence even to force retry if odd
 	;;
-
+	shr.u r2 = r2,r23
 	mf
-	xma.l f8=f6, f7, f8	// f8 (last_tick) <- -(lost + 1)*itm_delta + itm_next	(5 cyc)
-	nop 0
-
-	setf.sig f12=r31		// f12 <- ITC					(6 cyc)
-	// *** if (unlikely(read_seqretry(&xtime_lock, seq))) continue; ***
-	ld4 r24=[r17]			// r24 = xtime_lock->sequence (re-read)
-	nop 0
-	;;
-
-	xma.l f8=f11, f8, f12	// f8 (elapsed_cycles) <- (-1*last_tick + now) = (now - last_tick)
-	nop 0
-	;;
-
-	getf.sig r18=f8			// r18 <- (now - last_tick)
-	xmpy.l f8=f8, f10		// f8 <- elapsed_cycles*nsec_per_cyc (5 cyc)
-	add r3=r29, r14			// r3 = (nsec + old)
-	;;
-
-	cmp.lt p7, p8=r18, r0		// if now < last_tick, set p7 = 1, p8 = 0
-	getf.sig r18=f8			// r18 = elapsed_cycles*nsec_per_cyc		(6 cyc)
-	nop 0
-	;;
-
-(p10)	cmp.ne p9, p0=r23, r24		// if xtime_lock->sequence != seq, set p9
-	shr.u r18=r18, IA64_NSEC_PER_CYC_SHIFT	// r18 <- offset
-(p9)	br.spnt.many .retry
-	;;
-
-	mov ar.ccv=r14			// ar.ccv = old					(1 cyc)
-	cmp.leu p7, p8=r18, r14		// if (offset <= old), set p7 = 1, p8 = 0
-	;;
-
-(p8)	cmpxchg8.rel r24=[r25], r18, ar.ccv	// compare-and-exchange (atomic!)
-(p8)	add r3=r29, r18			// r3 = (nsec + offset)
-	;;
-	shr.u r3=r3, 3			// initiate dividing r3 by 1000
+	ld4 r25 = [r31]		// xtime_lock.sequence
 	;;
-	setf.sig f8=r3			//						(6 cyc)
-	mov r10=1000000			// r10 = 1000000
-	;;
-(p8)	cmp.ne.unc p9, p0=r24, r14
-	xmpy.hu f6=f8, f9		//						(5 cyc)
-(p9)	br.spnt.many .retry
-	;;
-
-	getf.sig r3=f6			//						(6 cyc)
-	;;
-	shr.u r3=r3, 4			// end of division, r3 is divided by 1000 (=usec)
-	;;
-
-1:	cmp.geu p7, p0=r3, r10		// while (usec >= 1000000)
-	;;
-(p7)	sub r3=r3, r10			// usec -= 1000000
-(p7)	adds r2=1, r2			// ++sec
-(p7)	br.spnt.many 1b
-
-	// finally: r2 = sec, r3 = usec
-EX(.fail_efault, st8 [r32]=r2)
-	adds r9=8, r32
-	mov r8=r0			// success
-	;;
-EX(.fail_efault, st8 [r9]=r3)		// store them in the timeval struct
-	mov r10=0
+	// End critical section.
+	add r22 = r22,r2	// Add xtime.nsecs
+	cmp4.ne p6,p0 = r25,r20
+(p6)	br.cond.dpnt.few .gettime	// sequence number changed ?
+	// Now r21=tv->tv_nsec and r22=tv->tv_sec
+	movl r2 = 1000000000
+(p14)	movl r3 = 2361183241434822607	// Prep for / 1000 hack
+	;;
+.time_normalize:
+	cmp.ge p6,p0 = r22,r2
+(p14)	shr.u r20 = r22, 3		// We can repeat this if necessary just wasting some time
+(p14)	setf.sig f7 = r3		// Chances for repeats are 1 in 10000 for gettod
+	;;
+(p14)	setf.sig f8 = r20
+(p6)	sub r22 = r22,r2
+(p6)	add r21 = 1,r21
+(p6)	br.cond.dpnt.few .time_normalize
+	;;
+EX(.fail_efault, st8 [r27] = r21)			// tv->tv_sec = seconds
+	// Divided by 8. Now divide by 125
+	// The compiler is able to do that with a multiply
+	// and a shift and we do the same
+(p14)	xmpy.hu f8 = f8, f7
+	;;
+(p14)	getf.sig r2 = f8
+	;;
+(p14)	shr.u r22 = r2, 4
+	;;
+EX(.fail_efault, st8 [r28] = r22)
+	mov r8 = r0
+	mov r10 = r0
 	FSYS_RETURN
-	/*
-	 * Note: We are NOT clearing the scratch registers here.  Since the only things
-	 *	 in those registers are time-related variables and some addresses (which
-	 *	 can be obtained from System.map), none of this should be security-sensitive
-	 *	 and we should be fine.
-	 */
-
 .fail_einval:
-	mov r8=EINVAL			// r8 = EINVAL
-	mov r10=-1			// r10 = -1
+	mov r8 = EINVAL
+	mov r10 = -1
 	FSYS_RETURN
-
 .fail_efault:
-	mov r8=EFAULT			// r8 = EFAULT
-	mov r10=-1			// r10 = -1
+	mov r8 = EFAULT
+	mov r10 = -1
 	FSYS_RETURN
 END(fsys_gettimeofday)
 
+ENTRY(fsys_clock_gettime)
+	.prologue
+	.altrp b6
+	.body
+	cmp.lt p6, p0 = CLOCK_MONOTONIC, r32
+	// Fallback if this is not CLOCK_REALTIME or CLOCK_MONOTONIC
+(p6)	br.spnt.many fsys_fallback_syscall
+	mov r27 = r33
+	shl r26 = r32,15
+	br.many .gettime
+END(fsys_clock_gettime)
+
 /*
  * long fsys_rt_sigprocmask (int how, sigset_t *set, sigset_t *oset, size_t sigsetsize).
  */
@@ -838,7 +826,7 @@
 	data8 0				// timer_getoverrun
 	data8 0				// timer_delete
 	data8 0				// clock_settime
-	data8 0				// clock_gettime
+	data8 fsys_clock_gettime	// clock_gettime
 	data8 0				// clock_getres		// 1255
 	data8 0				// clock_nanosleep
 	data8 0				// fstatfs64
Index: linux-2.6.7/arch/ia64/kernel/time.c
===================================================================
--- linux-2.6.7.orig/arch/ia64/kernel/time.c
+++ linux-2.6.7/arch/ia64/kernel/time.c
@@ -45,46 +45,7 @@
 
 #endif
 
-static void
-itc_reset (void)
-{
-}
-
-/*
- * Adjust for the fact that xtime has been advanced by delta_nsec (may be negative and/or
- * larger than NSEC_PER_SEC.
- */
-static void
-itc_update (long delta_nsec)
-{
-}
-
-/*
- * Return the number of nano-seconds that elapsed since the last
- * update to jiffy.  It is quite possible that the timer interrupt
- * will interrupt this and result in a race for any of jiffies,
- * wall_jiffies or itm_next.  Thus, the xtime_lock must be at least
- * read synchronised when calling this routine (see do_gettimeofday()
- * below for an example).
- */
-unsigned long
-itc_get_offset (void)
-{
-	unsigned long elapsed_cycles, lost = jiffies - wall_jiffies;
-	unsigned long now = ia64_get_itc(), last_tick;
-
-	last_tick = (cpu_data(TIME_KEEPER_ID)->itm_next
-		     - (lost + 1)*cpu_data(TIME_KEEPER_ID)->itm_delta);
-
-	elapsed_cycles = now - last_tick;
-	return (elapsed_cycles*local_cpu_data->nsec_per_cyc) >> IA64_NSEC_PER_CYC_SHIFT;
-}
-
-static struct time_interpolator itc_interpolator = {
-	.get_offset =	itc_get_offset,
-	.update =	itc_update,
-	.reset =	itc_reset
-};
+static struct time_interpolator itc_interpolator;
 
 int
 do_settimeofday (struct timespec *tv)
@@ -127,53 +88,15 @@
 void
 do_gettimeofday (struct timeval *tv)
 {
-	unsigned long seq, nsec, usec, sec, old, offset;
-
-	while (1) {
+	unsigned long seq, nsec, usec, sec, offset;
+	do {
 		seq = read_seqbegin(&xtime_lock);
-		{
-			old = last_nsec_offset;
-			offset = time_interpolator_get_offset();
-			sec = xtime.tv_sec;
-			nsec = xtime.tv_nsec;
-		}
-		if (unlikely(read_seqretry(&xtime_lock, seq)))
-			continue;
-		/*
-		 * Ensure that for any pair of causally ordered gettimeofday() calls, time
-		 * never goes backwards (even when ITC on different CPUs are not perfectly
-		 * synchronized).  (A pair of concurrent calls to gettimeofday() is by
-		 * definition non-causal and hence it makes no sense to talk about
-		 * time-continuity for such calls.)
-		 *
-		 * Doing this in a lock-free and race-free manner is tricky.  Here is why
-		 * it works (most of the time): read_seqretry() just succeeded, which
-		 * implies we calculated a consistent (valid) value for "offset".  If the
-		 * cmpxchg() below succeeds, we further know that last_nsec_offset still
-		 * has the same value as at the beginning of the loop, so there was
-		 * presumably no timer-tick or other updates to last_nsec_offset in the
-		 * meantime.  This isn't 100% true though: there _is_ a possibility of a
-		 * timer-tick occurring right right after read_seqretry() and then getting
-		 * zero or more other readers which will set last_nsec_offset to the same
-		 * value as the one we read at the beginning of the loop.  If this
-		 * happens, we'll end up returning a slightly newer time than we ought to
-		 * (the jump forward is at most "offset" nano-seconds).  There is no
-		 * danger of causing time to go backwards, though, so we are safe in that
-		 * sense.  We could make the probability of this unlucky case occurring
-		 * arbitrarily small by encoding a version number in last_nsec_offset, but
-		 * even without versioning, the probability of this unlucky case should be
-		 * so small that we won't worry about it.
-		 */
-		if (offset <= old) {
-			offset = old;
-			break;
-		} else if (likely(cmpxchg(&last_nsec_offset, old, offset) == old))
-			break;
+		offset = time_interpolator_get_offset();
+		sec = xtime.tv_sec;
+		nsec = xtime.tv_nsec;
+	} while (unlikely(read_seqretry(&xtime_lock, seq)));
 
-		/* someone else beat us to updating last_nsec_offset; try again */
-	}
-
-	usec = (nsec + offset) / 1000;
+       	usec = (nsec + offset) / 1000;
 
 	while (unlikely(usec >= USEC_PER_SEC)) {
 		usec -= USEC_PER_SEC;
@@ -323,6 +246,18 @@
 	ia64_set_itm(local_cpu_data->itm_next);
 }
 
+static int nojitter;
+
+static int __init nojitter_setup(char *str)
+{
+        nojitter = 1;
+        printk("Jitter checking for ITC timers disabled\n");
+        return 1;
+}
+
+__setup("nojitter", nojitter_setup);
+
+
 void __devinit
 ia64_init_itm (void)
 {
@@ -385,7 +320,27 @@
 
 	if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) {
 		itc_interpolator.frequency = local_cpu_data->itc_freq;
+		itc_interpolator.shift = 10;	/* accuracy ~200ns */
+		/* shift=16 yields a much better accuracy (~50ns) but runs
+		 * the risk of having the interpolator run too fast on some
+		 * systems
+		 */
 		itc_interpolator.drift = itc_drift;
+		itc_interpolator.source = TIME_SOURCE_CPU;
+#ifdef CONFIG_SMP
+		/* On IA64 in an SMP configuration ITCs are never accurately synchronized.
+		 * Jitter compensation requires a cmpxchg which may limit
+		 * the scalability of the syscalls for retrieving time.
+		 * The ITC synchronization is usually successful to within a few
+		 * ITC ticks but this is not a sure thing. If you need to improve
+		 * timer performance in SMP situations then boot the kernel with the
+		 * "nojitter" option. However, doing so may result in time fluctuating (maybe
+		 * even going backward) if the ITC offsets between the individual CPUs
+		 * are too large.
+		 */
+		if (!nojitter) itc_interpolator.source |= TIME_SOURCE_JITTER;
+#endif
+		itc_interpolator.addr = NULL;
 		register_time_interpolator(&itc_interpolator);
 	}
 
Index: linux-2.6.7/arch/ia64/sn/kernel/sn2/timer.c
===================================================================
--- linux-2.6.7.orig/arch/ia64/sn/kernel/sn2/timer.c
+++ linux-2.6.7/arch/ia64/sn/kernel/sn2/timer.c
@@ -20,57 +20,16 @@
 
 
 extern unsigned long sn_rtc_cycles_per_second;
-static volatile unsigned long last_wall_rtc;
 
-static unsigned long rtc_offset;	/* updated only when xtime write-lock is held! */
-static long rtc_nsecs_per_cycle;
-static long rtc_per_timer_tick;
-
-static unsigned long
-getoffset(void)
-{
-	return rtc_offset + (GET_RTC_COUNTER() - last_wall_rtc)*rtc_nsecs_per_cycle;
-}
-
-
-static void
-update(long delta_nsec)
-{
-	unsigned long rtc_counter = GET_RTC_COUNTER();
-	unsigned long offset = rtc_offset + (rtc_counter - last_wall_rtc)*rtc_nsecs_per_cycle;
-
-	/* Be careful about signed/unsigned comparisons here: */
-	if (delta_nsec < 0 || (unsigned long) delta_nsec < offset)
-		rtc_offset = offset - delta_nsec;
-	else
-		rtc_offset = 0;
-	last_wall_rtc = rtc_counter;
-}
-
-
-static void
-reset(void)
-{
-	rtc_offset = 0;
-	last_wall_rtc = GET_RTC_COUNTER();
-}
-
-
-static struct time_interpolator sn2_interpolator = {
-	.get_offset =	getoffset,
-	.update =	update,
-	.reset =	reset
-};
+static struct time_interpolator sn2_interpolator;
 
 void __init
 sn_timer_init(void)
 {
 	sn2_interpolator.frequency = sn_rtc_cycles_per_second;
 	sn2_interpolator.drift = -1;	/* unknown */
+	sn2_interpolator.shift = 0;	/* RTC is 54 bits maximum shift is 10 */
+	sn2_interpolator.addr = RTC_COUNTER_ADDR;
+	sn2_interpolator.source = TIME_SOURCE_MMIO64;
 	register_time_interpolator(&sn2_interpolator);
-
-	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();
 }
Index: linux-2.6.7/include/linux/timex.h
===================================================================
--- linux-2.6.7.orig/include/linux/timex.h
+++ linux-2.6.7/include/linux/timex.h
@@ -53,8 +53,10 @@
 
 #include <linux/config.h>
 #include <linux/compiler.h>
+#include <linux/jiffies.h>
 
 #include <asm/param.h>
+#include <asm/io.h>
 
 /*
  * The following defines establish the engineering parameters of the PLL
@@ -320,81 +322,130 @@
 
 #ifdef CONFIG_TIME_INTERPOLATION
 
+#define TIME_SOURCE_CPU 0x0100
+#define TIME_SOURCE_MMIO64 0x0200
+#define TIME_SOURCE_MMIO32 0x0400
+#define TIME_SOURCE_FUNCTION 0x0800
+
+/* TIME_SOURCE_JITTER compensates for a fluctuating timesource by always comparing
+   to the last value read from the timesource and never returning an earlier value.
+   Some timesources may fluctuate which may result in the strange phenomenon that
+   highly accurate timer calls seem to be stepping backward. The price to pay
+   for this compensation is that the timer routines are not as scalable anymore.
+*/
+#define TIME_SOURCE_JITTER 0x2000
+
+/* For proper operations time_interpolator clocks must run slightly slower
+   than the standard clock since the interpolator may only correct by having
+   time jump forward during a tick. A slower clock is usually a side effect
+   of the integer divide of the nanoseconds in a second by the frequency. 
+   The accuracy of the division can be increased by specifying a shift.
+   However, this may cause the clock not to be slow enough. If that is the
+   case then either the scaling needs to be reduced or a lower frequency
+   specified to slow down the interpolator.
+   A too fast interpolator will result in a time_interpolator_offset
+   that does not go back to zero once in a while. The interpolator
+   clock will become the time source for the system and the
+   logic for time adjustments in kernel/time.c will no longer work.
+*/
 struct time_interpolator {
-	/* cache-hot stuff first: */
-	unsigned long (*get_offset) (void);
-	void (*update) (long);
-	void (*reset) (void);
-
-	/* cache-cold stuff follows here: */
-	struct time_interpolator *next;
+	unsigned short source;		/* time source flag */
+	unsigned short shift;		/* increases accuracy of multiply by shifting. */
+			/* Note that bits may be lost if shift is set too high */
+	unsigned nsec_per_cyc;		/* set by register_time_interpolator() */
+	void *addr;			/* address of counter or function */
+	unsigned long offset;		/* nsec offset at last update */
+	unsigned long last_counter;	/* counter value in units of the counter at last update */
+	unsigned long last_cycle;	/* Last timer value if TIME_SOURCE_JITTER is set */
 	unsigned long frequency;	/* frequency in counts/second */
 	long drift;			/* drift in parts-per-million (or -1) */
+	struct time_interpolator *next;
 };
 
-extern volatile unsigned long last_nsec_offset;
-#ifndef __HAVE_ARCH_CMPXCHG
-extern spin_lock_t last_nsec_offset_lock;
-#endif
 extern struct time_interpolator *time_interpolator;
 
-extern void register_time_interpolator(struct time_interpolator *);
-extern void unregister_time_interpolator(struct time_interpolator *);
-
-/* Called with xtime WRITE-lock acquired.  */
-static inline void
-time_interpolator_update(long delta_nsec)
+static inline unsigned long
+time_interpolator_get_cycles(unsigned int src)
 {
-	struct time_interpolator *ti = time_interpolator;
+	unsigned long (*x)(void);
 
-	if (last_nsec_offset > 0) {
-#ifdef __HAVE_ARCH_CMPXCHG
-		unsigned long new, old;
+	switch (src & 0xF00)
+	{
+		case TIME_SOURCE_FUNCTION:
+			x = time_interpolator->addr;
+			return x();
 
-		do {
-			old = last_nsec_offset;
-			if (old > delta_nsec)
-				new = old - delta_nsec;
-			else
-				new = 0;
-		} while (cmpxchg(&last_nsec_offset, old, new) != old);
-#else
-		/*
-		 * This really hurts, because it serializes gettimeofday(), but without an
-		 * atomic single-word compare-and-exchange, there isn't all that much else
-		 * we can do.
-		 */
-		spin_lock(&last_nsec_offset_lock);
-		{
-			last_nsec_offset -= min(last_nsec_offset, delta_nsec);
-		}
-		spin_unlock(&last_nsec_offset_lock);
-#endif
+		case TIME_SOURCE_MMIO64	:
+			return readq(time_interpolator->addr);
+
+		case TIME_SOURCE_MMIO32	:
+			return readl(time_interpolator->addr);
+
+		default: return get_cycles();
 	}
+}
+
+static inline unsigned long
+time_interpolator_get_counter(void)
+{
+	unsigned int src = time_interpolator->source;
 
-	if (ti)
-		(*ti->update)(delta_nsec);
+	if (src && TIME_SOURCE_JITTER)
+	{
+		unsigned long lcycle;
+		unsigned long now;
+		
+		do {
+			lcycle = time_interpolator->last_cycle;
+			now = time_interpolator_get_cycles(src);
+			/* If the jitter causes the timer to return an earlier value return last value */
+			if (lcycle && time_after(lcycle,now)) return lcycle;
+			/* Keep track of the last timer value returned. The use of cmpxchg here
+			 * will cause contention in an SMP environment and better be avoided.
+			 */
+		} while (unlikely(cmpxchg(&time_interpolator->last_cycle,lcycle,now) != lcycle));
+		return now;
+	}
+	else
+		return time_interpolator_get_cycles(src);
 }
 
-/* Called with xtime WRITE-lock acquired.  */
+extern void register_time_interpolator(struct time_interpolator *);
+extern void unregister_time_interpolator(struct time_interpolator *);
+
 static inline void
 time_interpolator_reset(void)
 {
-	struct time_interpolator *ti = time_interpolator;
-
-	last_nsec_offset = 0;
-	if (ti)
-		(*ti->reset)();
+	time_interpolator->offset = 0;
+	time_interpolator->last_counter = time_interpolator_get_counter();
 }
 
-/* Called with xtime READ-lock acquired.  */
+#define GET_TI_NSECS(count,i) ((((count) - i->last_counter) * i->nsec_per_cyc) >> i->shift)
+
 static inline unsigned long
 time_interpolator_get_offset(void)
 {
-	struct time_interpolator *ti = time_interpolator;
-	if (ti)
-		return (*ti->get_offset)();
-	return last_nsec_offset;
+	return time_interpolator->offset +
+		GET_TI_NSECS(time_interpolator_get_counter(),time_interpolator);
+}
+
+static inline void time_interpolator_update(long delta_nsec)
+{
+	unsigned long counter=time_interpolator_get_counter();
+	unsigned long offset=time_interpolator->offset + GET_TI_NSECS(counter,time_interpolator);
+
+	/* The interpolator compensates for late ticks by accumulating
+         * the late time in interpolator_offset. A tick earlier than
+	 * expected will lead to a reset of the offset and a corresponding
+	 * jump of the clock forward. Again this only works if the
+	 * interpolator clock is running slightly slower than the regular clock. 
+         */
+
+	if (delta_nsec < 0 || (unsigned long) delta_nsec < offset)
+		time_interpolator->offset = offset - delta_nsec;
+	else
+		time_interpolator->offset = 0;			/* Early tick. Resync */
+	time_interpolator->last_counter = counter;
 }
 
 #else /* !CONFIG_TIME_INTERPOLATION */
Index: linux-2.6.7/kernel/timer.c
===================================================================
--- linux-2.6.7.orig/kernel/timer.c
+++ linux-2.6.7/kernel/timer.c
@@ -1425,10 +1425,6 @@
 }
 
 #ifdef CONFIG_TIME_INTERPOLATION
-volatile unsigned long last_nsec_offset;
-#ifndef __HAVE_ARCH_CMPXCHG
-spinlock_t last_nsec_offset_lock = SPIN_LOCK_UNLOCKED;
-#endif
 
 struct time_interpolator *time_interpolator;
 static struct time_interpolator *time_interpolator_list;
@@ -1439,17 +1435,21 @@
 {
 	if (!time_interpolator)
 		return 1;
-	return new->frequency > 2*time_interpolator->frequency ||
+	return new->frequency > 2 * time_interpolator->frequency ||
 	    (unsigned long)new->drift < (unsigned long)time_interpolator->drift;
 }
 
 void
 register_time_interpolator(struct time_interpolator *ti)
 {
+	ti->nsec_per_cyc = (NSEC_PER_SEC << ti->shift) / ti->frequency;
 	spin_lock(&time_interpolator_lock);
 	write_seqlock_irq(&xtime_lock);
 	if (is_better_time_interpolator(ti))
+	{
 		time_interpolator = ti;
+		time_interpolator_reset();
+	}
 	write_sequnlock_irq(&xtime_lock);
 
 	ti->next = time_interpolator_list;
@@ -1480,6 +1480,7 @@
 		for (curr = time_interpolator_list; curr; curr = curr->next)
 			if (is_better_time_interpolator(curr))
 				time_interpolator = curr;
+		time_interpolator_reset();
 	}
 	write_sequnlock_irq(&xtime_lock);
 	spin_unlock(&time_interpolator_lock);
Index: linux-2.6.7/arch/ia64/kernel/asm-offsets.c
===================================================================
--- linux-2.6.7.orig/arch/ia64/kernel/asm-offsets.c
+++ linux-2.6.7/arch/ia64/kernel/asm-offsets.c
@@ -187,14 +187,6 @@
 	DEFINE(IA64_CLONE_VFORK, CLONE_VFORK);
 	DEFINE(IA64_CLONE_VM, CLONE_VM);
 
-	BLANK();
-    /* used by fsys_gettimeofday in arch/ia64/kernel/fsys.S */
-	DEFINE(IA64_CPUINFO_ITM_DELTA_OFFSET, offsetof (struct cpuinfo_ia64, itm_delta));
-	DEFINE(IA64_CPUINFO_ITM_NEXT_OFFSET, offsetof (struct cpuinfo_ia64, itm_next));
-	DEFINE(IA64_CPUINFO_NSEC_PER_CYC_OFFSET, offsetof (struct cpuinfo_ia64, nsec_per_cyc));
-	DEFINE(IA64_TIMESPEC_TV_NSEC_OFFSET, offsetof (struct timespec, tv_nsec));
-
-
 	DEFINE(CLONE_IDLETASK_BIT, 12);
 #if CLONE_IDLETASK != (1 << 12)
 # error "CLONE_IDLETASK_BIT incorrect, please fix"
@@ -207,5 +199,21 @@
 
 	BLANK();
 	DEFINE(IA64_MCA_TLB_INFO_SIZE, sizeof (struct ia64_mca_tlb_info));
+	/* used by head.S */
+	DEFINE(IA64_CPUINFO_NSEC_PER_CYC_OFFSET, offsetof (struct cpuinfo_ia64, nsec_per_cyc));
 
+	BLANK();
+	/* used by fsys_gettimeofday in arch/ia64/kernel/fsys.S */
+	DEFINE(IA64_TIME_INTERPOLATOR_ADDRESS_OFFSET, offsetof (struct time_interpolator, addr));
+	DEFINE(IA64_TIME_INTERPOLATOR_SOURCE_OFFSET, offsetof (struct time_interpolator, source));
+	DEFINE(IA64_TIME_INTERPOLATOR_SHIFT_OFFSET, offsetof (struct time_interpolator, shift));
+	DEFINE(IA64_TIME_INTERPOLATOR_NSEC_OFFSET, offsetof (struct time_interpolator, nsec_per_cyc));
+	DEFINE(IA64_TIME_INTERPOLATOR_OFFSET_OFFSET, offsetof (struct time_interpolator, offset));
+	DEFINE(IA64_TIME_INTERPOLATOR_LAST_CYCLE_OFFSET, offsetof (struct time_interpolator, last_cycle));
+	DEFINE(IA64_TIME_INTERPOLATOR_LAST_COUNTER_OFFSET, offsetof (struct time_interpolator, last_counter));
+	DEFINE(IA64_TIME_SOURCE_CPU, TIME_SOURCE_CPU);
+	DEFINE(IA64_TIME_SOURCE_JITTER, TIME_SOURCE_JITTER);
+	DEFINE(IA64_TIME_SOURCE_MMIO64, TIME_SOURCE_MMIO64);
+	DEFINE(IA64_TIME_SOURCE_MMIO32, TIME_SOURCE_MMIO32);
+	DEFINE(IA64_TIMESPEC_TV_NSEC_OFFSET, offsetof (struct timespec, tv_nsec));
 }