>
> " always turned out to be 71 minutes 35 seconds, which is 2^32
> " usec.]
>
> Huh, thats right. I'm seeing a 4294 second jump on the hosts that jump an
> hour.
> It happens with both xm shutdown and xm destroy.
OK, this bug is now officially annoying me.
I've checked in a tiny fix I spotted in a code review, but I
doubt it will solve the problem.
I think the easiest way to solve it since we can't reproduce
locally is to apply tracing.
David: please can you apply the following patch to
linux-2.6.8.1-xen-sparse/arch/xen/i386/kernel/time.c and see what
comes out when you run your test. It's also interesting to see
what output comes out after the time skip whenever you run date.
Thanks,
Ian
---
/usr/groups/xeno/BK/xeno.bk/linux-2.6.8.1-xen-sparse/arch/xen/i386/kernel/time.c
2004-09-30 21:14:58.000000000 +0100
+++ linux-2.6.8.1-xen-sparse/arch/xen/i386/kernel/time.c 2004-09-30
21:28:09.000000000 +0100
@@ -114,28 +114,34 @@
#define NS_PER_TICK (1000000000ULL/HZ)
-#define HANDLE_USEC_UNDERFLOW(_tv) do { \
+#define HANDLE_USEC_UNDERFLOW(_tv) do { int i=0; \
while ((_tv).tv_usec < 0) { \
(_tv).tv_usec += USEC_PER_SEC; \
(_tv).tv_sec--; \
- } \
+ }if(i>100)printk(KERN_ALERT"USEC_UNDER %d\n",i); \
} while (0)
-#define HANDLE_USEC_OVERFLOW(_tv) do { \
+#define HANDLE_USEC_OVERFLOW(_tv) do { int i=0; \
while ((_tv).tv_usec >= USEC_PER_SEC) { \
(_tv).tv_usec -= USEC_PER_SEC; \
- (_tv).tv_sec++; \
- } \
+ (_tv).tv_sec++; i++; \
+ }if(i>100)printk(KERN_ALERT"USEC_OVER %d\n",i); \
} while (0)
static inline void __normalize_time(time_t *sec, s64 *nsec)
{
+int i=0,j=0;
while (*nsec >= NSEC_PER_SEC) {
(*nsec) -= NSEC_PER_SEC;
(*sec)++;
+ i++;
}
while (*nsec < 0) {
(*nsec) += NSEC_PER_SEC;
(*sec)--;
+ j++;
}
+
+if( i>100 || j>100 ) printk(KERN_ALERT"normalize time %d %d\n",i,j);
+
}
/* Does this guest OS track Xen time, or set its wall clock independently? */
@@ -155,6 +161,8 @@
*/
static void __get_time_values_from_xen(void)
{
+long last = shadow_tv.tv_sec;
+
shared_info_t *s = HYPERVISOR_shared_info;
do {
@@ -169,6 +177,7 @@
while (shadow_time_version != s->time_version1);
cur_timer->mark_offset();
+if( shadow_tv.tv_sec-last > 600 ) printk(KERN_ALERT"****
__get_time_values_from_xen(void) JUPMED!\n");
}
#define TIME_VALUES_UP_TO_DATE \
@@ -241,6 +250,7 @@
((sec == last_seen_tv.tv_sec) && (usec < last_seen_tv.tv_usec))) {
sec = last_seen_tv.tv_sec;
usec = last_seen_tv.tv_usec;
+printk(KERN_ALERT"Clamp time %ld %ld\n",sec,last_seen_tv.tv_sec);
} else {
last_seen_tv.tv_sec = sec;
last_seen_tv.tv_usec = usec;
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