From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Dan Magenheimer" Subject: RE: Re: Fix for get_s_time() Date: Mon, 28 Apr 2008 11:39:57 -0600 Message-ID: <20080428113957734.00000002360@djm-pc> References: Reply-To: "dan.magenheimer@oracle.com" Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============1620139363==" Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Mime-version: 1.0 Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Dave Winchell Cc: "Tian, Kevin" , "xen-devel@lists.xensource.com" , Ian Pratt , Keir Fraser List-Id: xen-devel@lists.xenproject.org This is a multi-part message in MIME format --===============1620139363== Content-Type: multipart/alternative; boundary=-------7844a9b7844a9b This is a multi-part message in MIME format ---------7844a9b7844a9b Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable RE: [Xen-devel] Re: Fix for get_s_time()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@virtualiron.com] Sent: Friday, April 25, 2008 7:54 PM To: dan.magenheimer@oracle.com Cc: Keir Fraser; Tian, Kevin; xen-devel@lists.xensource.com; Ian Pratt; D= ave 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@oracle.com] Sent: Fri 4/25/2008 5:03 PM To: Dave Winchell Cc: Keir Fraser; Tian, Kevin; xen-devel@lists.xensource.com; 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@virtualiron.com] > Sent: Friday, April 25, 2008 1:48 PM > To: Dave Winchell > Cc: Keir Fraser; Tian, Kevin; dan.magenheimer@oracle.com; > xen-devel@lists.xensource.com; 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" > 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 > >> > >> > >> > >> > > > > > ---------7844a9b7844a9b Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable RE: [Xen-devel] Re: Fix for get_s_time()
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 w= ords, = should the virtual pit be based on
system time = also?
 
Dan
-----Original Message-----
From: Dave Winchell = [mailto:dwinchell@virtualiron.com]
Sent: Friday, April 25, 2008= 7:54 = PM
To: dan.magenheimer@oracle.com
Cc: Keir Fraser; Ti= an, = Kevin; xen-devel@lists.xensource.com; Ian Pratt; Dave = Winchell
Subject: RE: [Xen-devel] Re: Fix for = get_s_time()