Re: [Xen-devel] [Xen-users] Re: Xen 4 TSC problems

[Olivier Hanesse <olivier.hanesse@xxxxxxxxx>]

Hello,

From my point of view, this was a kind of xen hardware "incompatibility/bug" : I was able to reproduce this bug on more than 50 identical servers, but not on another farm of servers with a different hardware.

Xen version, Debian Kernel was exactly the same on both farm.

Regards

Olivier

2012/9/27 Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>

> From: Mauro [mailto:mrsanna1@xxxxxxxxx]
> Sent: Thursday, September 27, 2012 9:55 AM
> To: Olivier Hanesse
> Cc: Dan Magenheimer; Jeremy Fitzhardinge; xen-devel@xxxxxxxxxxxxxxxxxxx; Keir Fraser; Jan Beulich;
> Keir Fraser; Xen Users; Mark Adams
> Subject: Re: [Xen-users] Re: [Xen-devel] Xen 4 TSC problems

>
> On 28 February 2011 16:54, Olivier Hanesse <olivier.hanesse@xxxxxxxxx> wrote:
> > Yes this is what I mean.
> > I am glad to hear that it isn't a bad sign :)
> > I thought of a bad sign, because on system with "reliable TSC", this counter
> > is always 0.
>
> Hey men.
> I have exactly the same problem.
> I have two cluster nodes.
> Server are two HP Proliant DL 580 G4 with four Quad Core Intel(R)
> Xeon(R) CPU E7330  @ 2.40GHz.
> I'm running debian squeeze in dom0s end domUs.

Hi Mauro --

There's been a lot of work on clocks since 4.0 (by other Xen developers,
not me).  I don't think this specific problem was ever reproduced
by a developer so I don't think anyone knows if it has been
already fixed or not, nor are there any plans to backport all the
timer work to 4.0.

You might try upgrading your Xen hypervisor to the just-released
Xen 4.2 [1] and see if the problem goes away.  If the problem still
exists in 4.2, it may be easier to get some developer to pay attention
to it.  It may be specific hardware or processors or power
management or firmware or even dom0 kernel, so the first thing
to do is try later hypervisor bits.

Sorry I can't be more helpful.  Good luck!

Dan

[1] Sorry, I'm not familiar with the 4.0->4.2 upgrade process
so you may want to confirm with others.

> xm info:
>
> host                   : xen-p01
> release                : 2.6.32-5-xen-amd64
> version                : #1 SMP Sun May 6 08:57:29 UTC 2012
> machine                : x86_64
> nr_cpus                : 16
> nr_nodes               : 1
> cores_per_socket       : 4
> threads_per_core       : 1
> cpu_mhz                : 2400
> hw_caps                :
> bfebfbff:20100800:00000000:00000940:0004e3bd:00000000:00000001:00000000
> virt_caps              : hvm
> total_memory           : 65532
> free_memory            : 40317
> node_to_cpu            : node0:0-15
> node_to_memory         : node0:40317
> node_to_dma32_mem      : node0:3256
> max_node_id            : 0
> xen_major              : 4
> xen_minor              : 0
> xen_extra              : .1
> xen_caps               : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32
> hvm-3.0-x86_32p hvm-3.0-x86_64
> xen_scheduler          : credit
> xen_pagesize           : 4096
> platform_params        : virt_start=0xffff800000000000
> xen_changeset          : unavailable
> xen_commandline        : placeholder dom0_mem=3072M loglvl=warning
> guest_loglvl=warning
> cc_compiler            : gcc version 4.4.5 (Debian 4.4.5-8)
> cc_compile_by          : ultrotter
> cc_compile_domain      : debian.org
> cc_compile_date        : Sat Sep  8 19:15:46 UTC 2012
> xend_config_format     : 4
>
> I'm experiencing weekly a clock jump ahead of about 50 minutes on dom0.
> I'm seriously in trouble because it cause every time a reboot of one
> of the two nodes clusters.

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