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Re: [Xen-devel] [PATCH][RFC] remove PV/x86 warnings (timewentbackwards)

To: "Jan Beulich" <jbeulich@xxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH][RFC] remove PV/x86 warnings (timewentbackwards)
From: Atsushi SAKAI <sakaia@xxxxxxxxxxxxxx>
Date: Thu, 11 Dec 2008 20:00:26 +0900
Cc: kevin.tian@xxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxx, Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
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Hi, Keir, Kevin, and Jan

  Thank you for various suggestions.

One more questions on this.
I think possible solution is
Sync vcpu0 per_cpu(processed_system_time)
to static u64 processed_system_time on PV kernel.

It must be solved on hypervisor layer in this case?

Thanks
Atsushi SAKAI


"Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:

> >>> Keir Fraser <keir.fraser@xxxxxxxxxxxxx> 11.12.08 10:22 >>>
> >On 11/12/2008 08:02, "Atsushi SAKAI" <sakaia@xxxxxxxxxxxxxx> wrote:
> >
> >> 
> >> This patch intends to remove warnings for Time went backwards
> >> (negative delta) like follows.
> >> ========from Xen BZ 195
> >> Timer ISR/0: Time went backwards: delta=-10048465 cpu_delta=9951535
> >> shadow=706605145 0: 71640046095
> >> ========
> >
> >That might be considered skirting around the problem. Are users still seeing
> >this with xen 3.3 and xen unstable?
> 
> Unfortunately yes, but rather seldom these days. We just got a fresh
> report about a larger IBM system suffering from it - while the initial report
> they sent had hundreds of milliseconds in them, the most up-to-date
> one we have shows that it's just a few milliseconds above the -10ms
> boundary. So far I haven't been able to figure what causes this.
> 
> Jan
> 
> 
> _______________________________________________
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