WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

RE: [Xen-devel] Re: Fix for get_s_time()

To: "Dave Winchell" <dwinchell@xxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] Re: Fix for get_s_time()
From: "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx>
Date: Mon, 28 Apr 2008 11:39:57 -0600
Cc: "Tian, Kevin" <kevin.tian@xxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Ian Pratt <Ian.Pratt@xxxxxxxxxxxxx>, Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Delivery-date: Mon, 28 Apr 2008 10:41:37 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <B99564216C25704085A82B41C46DD3427B05DC@xxxxxxxxxxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Organization: Oracle Corporation
Reply-to: "dan.magenheimer@xxxxxxxxxx" <dan.magenheimer@xxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AcinF84pp4+PJwSlRYmeamaLzOoQeQAJvVoDAIXuy3A=
Hi Dave --
 
> You know, its more like hpet on system time.
 
I wonder how much of the problems we observed with skew on pit was due to
the pit-on-tsc "bug"... in other words, should the virtual pit be based on
system time also?
 
Dan

-----Original Message-----
From: Dave Winchell [mailto:dwinchell@xxxxxxxxxxxxxxx]
Sent: Friday, April 25, 2008 7:54 PM
To: dan.magenheimer@xxxxxxxxxx
Cc: Keir Fraser; Tian, Kevin; xen-devel@xxxxxxxxxxxxxxxxxxx; Ian Pratt; Dave Winchell
Subject: RE: [Xen-devel] Re: Fix for get_s_time()

Hi Dan,

I just need to remove some debug and merge with unstable.
I should be able to send you a patch Monday or Tuesday.
You know, its more like hpet on system time.
Thanks for the testing offer.

Regards,
Dave


-----Original Message-----
From: Dan Magenheimer [mailto:dan.magenheimer@xxxxxxxxxx]
Sent: Fri 4/25/2008 5:03 PM
To: Dave Winchell
Cc: Keir Fraser; Tian, Kevin; xen-devel@xxxxxxxxxxxxxxxxxxx; Ian Pratt
Subject: RE: [Xen-devel] Re: Fix for get_s_time()

Hi Dave --

Are you ready to release the guest-virtual-platform-timer
on xen-system-time patch yet?  If so, we'd be happy to
give it some testing.

Thanks,
Dan

> -----Original Message-----
> From: Dave Winchell [mailto:dwinchell@xxxxxxxxxxxxxxx]
> Sent: Friday, April 25, 2008 1:48 PM
> To: Dave Winchell
> Cc: Keir Fraser; Tian, Kevin; dan.magenheimer@xxxxxxxxxx;
> xen-devel@xxxxxxxxxxxxxxxxxxx; Ian Pratt; Dave Winchell
> Subject: Re: [Xen-devel] Re: Fix for get_s_time()
>
>
> Keir,
>
> Last nights run had the error in the 12 ppm range.
> Here is the change we have been talking about.
>
> -Dave
>
> Dave Winchell wrote:
>
> > Keir Fraser wrote:
> >
> >> On 24/4/08 17:04, "Dave Winchell"
> <dwinchell@xxxxxxxxxxxxxxx> wrote:
> >>
> >>
> >>
> >>> yes, this is the issue. What you suggest should be fine
> and I am trying
> >>> it now.
> >>> With the locking version (and a fix to a bug I
> introduced) I got .0012%
> >>> error
> >>> on an overnight run with hpet layered on
> get_s_time_mono(), which is
> >>> the
> >>> max(prev, cur) layer on get_s_time we discussed.
> >>>
> >>
> >>
> >> 12 parts per million is pretty good. Is that cumulative deviation
> >> from 'wall
> >> time' over ~12 hours?
> >>
> > yes, deviation between the guest's time and an ntp reference.
> >
> >> That could easily be explained by the fact that Xen
> >> system time is not sync'ed with ntp.
> >>
> >>
> > That's true. And, as we have discussed, this error seems to
> vary quite
> > a bit
> > platform to platform for some reason. I will verify that
> this still is
> > the case.
> >
> > -Dave
> >
> >> -- Keir
> >>
> >>
> >>
> >>
> >
>
>
>


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel