On Fri, May 02, 2008 at 12:34:54AM +0100, Nix wrote:
> loki:/tmp# /usr/bin/ntpdate -bv hades
> 30 Apr 22:45:52 ntpdate[8833]: ntpdate [EMAIL PROTECTED] Fri Feb 22 18:37:11
> UTC 2008 (1)
> 30 Apr 22:45:52 ntpdate[8833]: step time server 192.168.14.18 offset
> -5.728539 sec
>
> so in effect yes :)
>
> Hm. A five-second skip forwards via date --set works fine. A five-second
> skip *backwards*, and instant boom.
I tried both directions for the hell of it.
With your config, I'm seeing a hang until the system time catches up
to what UML thought it should have been in the first place. But it's
only a few seconds, not forever.
However, stracing it did reveal a bogus interval trying to be set,
which the patch below fixes. It doesn't cause any behavior change
here, so YMMV.
This includes the previous patch, which I think is a good idea anyway,
so back that out and drop this in its place.
Jeff
Index: linux-2.6.22/arch/um/os-Linux/time.c
===================================================================
--- linux-2.6.22.orig/arch/um/os-Linux/time.c 2008-04-24 13:21:28.000000000
-0400
+++ linux-2.6.22/arch/um/os-Linux/time.c 2008-05-02 12:21:01.000000000
-0400
@@ -107,6 +107,10 @@ static void deliver_alarm(void)
unsigned long long this_tick = os_nsecs();
int one_tick = UM_NSEC_PER_SEC / UM_HZ;
+ /* Protection against the host's time going backwards */
+ if ((last_tick != 0) && (this_tick < last_tick))
+ this_tick = last_tick;
+
if (last_tick == 0)
last_tick = this_tick - one_tick;
@@ -149,6 +153,9 @@ static int after_sleep_interval(struct t
start_usecs = usec;
start_usecs -= skew / UM_NSEC_PER_USEC;
+ if (start_usecs < 0)
+ start_usecs = 0;
+
tv = ((struct timeval) { .tv_sec = start_usecs / UM_USEC_PER_SEC,
.tv_usec = start_usecs % UM_USEC_PER_SEC });
interval = ((struct itimerval) { { 0, usec }, tv });
--
Work email - jdike at linux dot intel dot com
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