Hongming Xiao
2008-Sep-25 22:13 UTC
[Xen-users] domu''s time is frozen after change dom0''s time backward
All, Hope this is the right list to post my question. I noticed that once I changed dom0''s time backward, domU''s time will be frozen. Here is the step to reproduce the problem. a) sync domU''s time with dom0 by running following command in domU # echo 0 > /proc/sys/xen/independent_wallclock b) Verify domU''s time is synced to dom0''s In dom0: # date Thu Sep 25 12:10:03 EDT 2008 In domU: # date Thu Sep 25 12:10:04 EDT 2008 c) Change dom0''s time backward for 1 hour In dom0: # date 0925110000 In dom0: # daten Thu Sep 25 11:00:02 EDT 2008 d) Then, domU''s time is frozen at the time we made change to dom0''s time. In domU: # date Thu Sep 25 12:11:00 EDT 2008 # date Thu Sep 25 12:11:00 EDT 2008 # date Thu Sep 25 12:11:00 EDT 2008 .... domU''s time can be unfrozen by making domU''s time older than dom0''s, no matter by changing dom0 or domU''s time. In domU: (change domU''s time backward) # date 0925100000 In domU: # date Thu Sep 25 11:01:00 EDT 2008 Question: Appearently, Xen will stop syncing domU''s time if dom0''s time is older than domU''s. Is it possible to configure Xen to let it sync domU''s time to dom0''s (not matter what dom0''s time is)? Thanks in advance, Bill Wei _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hongming Xiao
2008-Sep-26 14:44 UTC
[Xen-users] Re: domu''s time is frozen after change dom0''s time backward
ooops, forgot to provide OS and xen version info.
When test, ntpd was not running.
OS: CentOS 5.2 (both domU and dom0)
Output of "xm info"
xm info
host : 302472-lab1.hq.avaya.com
release : 2.6.18-92.1.6.el5xen
version : #1 SMP Wed Jun 25 14:13:10 EDT 2008
machine : x86_64
nr_cpus : 8
nr_nodes : 1
sockets_per_node : 2
cores_per_socket : 4
threads_per_core : 1
cpu_mhz : 2327
hw_caps :
bfebfbff:20100800:00000000:00000140:000ce3bd:00000000:0
0000001
total_memory : 6138
free_memory : 1
node_to_cpu : node0:0-7
xen_major : 3
xen_minor : 1
xen_extra : .2-92.1.6.el5
xen_caps : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32
hvm-3.0-x
86_32p hvm-3.0-x86_64
xen_pagesize : 4096
platform_params : virt_start=0xffff800000000000
xen_changeset : unavailable
cc_compiler : gcc version 4.1.2 20071124 (Red Hat 4.1.2-42)
cc_compile_by : mockbuild
cc_compile_domain : centos.org
cc_compile_date : Wed Jun 25 13:39:56 EDT 2008
xend_config_format : 2
On Thu, Sep 25, 2008 at 6:13 PM, Hongming Xiao <xiaohm@gmail.com>
wrote:> All,
>
> Hope this is the right list to post my question.
>
> I noticed that once I changed dom0''s time backward,
domU''s time will
> be frozen. Here is the step to reproduce the problem.
>
> a) sync domU''s time with dom0 by running following command in domU
>
> # echo 0 > /proc/sys/xen/independent_wallclock
>
> b) Verify domU''s time is synced to dom0''s
>
> In dom0:
> # date
> Thu Sep 25 12:10:03 EDT 2008
>
> In domU:
> # date
> Thu Sep 25 12:10:04 EDT 2008
>
> c) Change dom0''s time backward for 1 hour
>
> In dom0:
> # date 0925110000
>
> In dom0:
> # daten
> Thu Sep 25 11:00:02 EDT 2008
>
> d) Then, domU''s time is frozen at the time we made change to
dom0''s time.
>
> In domU:
> # date
> Thu Sep 25 12:11:00 EDT 2008
> # date
> Thu Sep 25 12:11:00 EDT 2008
> # date
> Thu Sep 25 12:11:00 EDT 2008
> ....
>
> domU''s time can be unfrozen by making domU''s time older
than dom0''s,
> no matter by changing dom0 or domU''s time.
>
> In domU: (change domU''s time backward)
> # date 0925100000
>
> In domU:
> # date
> Thu Sep 25 11:01:00 EDT 2008
>
>
> Question:
>
> Appearently, Xen will stop syncing domU''s time if dom0''s
time is older
> than domU''s. Is it possible to configure Xen to let it sync
domU''s
> time to dom0''s (not matter what dom0''s time is)?
>
> Thanks in advance,
> Bill Wei
>
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Hongming Xiao
2008-Oct-07 15:28 UTC
[Xen-users] Re: domu''s time is frozen after change dom0''s time backward
Can somebody let me know this is a known issue or my configuration issue? BTW, I am using full hardware based virtualization. Will it make any difference? TIA On Fri, Sep 26, 2008 at 10:44 AM, Hongming Xiao <xiaohm@gmail.com> wrote:> ooops, forgot to provide OS and xen version info. > > When test, ntpd was not running. > OS: CentOS 5.2 (both domU and dom0) > Output of "xm info" > > xm info > host : 302472-lab1.hq.avaya.com > release : 2.6.18-92.1.6.el5xen > version : #1 SMP Wed Jun 25 14:13:10 EDT 2008 > machine : x86_64 > nr_cpus : 8 > nr_nodes : 1 > sockets_per_node : 2 > cores_per_socket : 4 > threads_per_core : 1 > cpu_mhz : 2327 > hw_caps : > bfebfbff:20100800:00000000:00000140:000ce3bd:00000000:0 > > 0000001 > total_memory : 6138 > free_memory : 1 > node_to_cpu : node0:0-7 > xen_major : 3 > xen_minor : 1 > xen_extra : .2-92.1.6.el5 > xen_caps : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 > hvm-3.0-x > > 86_32p hvm-3.0-x86_64 > xen_pagesize : 4096 > platform_params : virt_start=0xffff800000000000 > xen_changeset : unavailable > cc_compiler : gcc version 4.1.2 20071124 (Red Hat 4.1.2-42) > cc_compile_by : mockbuild > cc_compile_domain : centos.org > cc_compile_date : Wed Jun 25 13:39:56 EDT 2008 > xend_config_format : 2 > > On Thu, Sep 25, 2008 at 6:13 PM, Hongming Xiao <xiaohm@gmail.com> wrote: >> All, >> >> Hope this is the right list to post my question. >> >> I noticed that once I changed dom0''s time backward, domU''s time will >> be frozen. Here is the step to reproduce the problem. >> >> a) sync domU''s time with dom0 by running following command in domU >> >> # echo 0 > /proc/sys/xen/independent_wallclock >> >> b) Verify domU''s time is synced to dom0''s >> >> In dom0: >> # date >> Thu Sep 25 12:10:03 EDT 2008 >> >> In domU: >> # date >> Thu Sep 25 12:10:04 EDT 2008 >> >> c) Change dom0''s time backward for 1 hour >> >> In dom0: >> # date 0925110000 >> >> In dom0: >> # daten >> Thu Sep 25 11:00:02 EDT 2008 >> >> d) Then, domU''s time is frozen at the time we made change to dom0''s time. >> >> In domU: >> # date >> Thu Sep 25 12:11:00 EDT 2008 >> # date >> Thu Sep 25 12:11:00 EDT 2008 >> # date >> Thu Sep 25 12:11:00 EDT 2008 >> .... >> >> domU''s time can be unfrozen by making domU''s time older than dom0''s, >> no matter by changing dom0 or domU''s time. >> >> In domU: (change domU''s time backward) >> # date 0925100000 >> >> In domU: >> # date >> Thu Sep 25 11:01:00 EDT 2008 >> >> >> Question: >> >> Appearently, Xen will stop syncing domU''s time if dom0''s time is older >> than domU''s. Is it possible to configure Xen to let it sync domU''s >> time to dom0''s (not matter what dom0''s time is)? >> >> Thanks in advance, >> Bill Wei >> >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users