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-users

[Xen-devel] Re: [Xen-users] ntpd under Xen Dom0 exhibits extremely high

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Subject: [Xen-devel] Re: [Xen-users] ntpd under Xen Dom0 exhibits extremely high jitter/noise? runs stable/quiet under non-xen kernel.
From: mail ignored <0.bugs.only.0@xxxxxxxxx>
Date: Mon, 18 Jan 2010 10:19:52 -0800
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Xen User-List <xen-users@xxxxxxxxxxxxxxxxxxx>
Delivery-date: Mon, 18 Jan 2010 10:20:45 -0800
Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:cc:content-type; bh=OUHWGLPoTByAHD9p0AQrhumsHr3f44mHyb0hvB4CpJM=; b=jVkOQh+GQFuCbdVBokzNtKt/A7yFZlaBWmOW+aaOtnBrlufcEEPE6S6JPDaw0H2OaC COeJmJ34a1aSbzz8+LNrLzfcOlmi5vl2rYxBHyqxDjdioOvZpIsyBfOcvpSYVjcftmex RD+GWZqoj5IAwGsFBZOrKN2q88WY8I49ukYuE=
Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=ktagWi5nUb5ixox8992wvu5VvXUHL66mPRbEcY8B9h6lNAlzEfwMwfXacNzLfn/cNW 9vmJSLdShUjYgAav6R+RxX8Exegvb9dTnqR+rXJLzZyft1cKEOM78BHcM5s60uWFg0oD ansu4qDSqD3e1bh4ZXpf3INCPpKqiDIvkLnQI=
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <c67eed301001180921u6ab1771fq764d51c9ddf92ab9@xxxxxxxxxxxxxx>
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/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <c67eed301001171421y5e7cbd02me2e5753922bc1c44@xxxxxxxxxxxxxx> <C779BDF0.6799%keir.fraser@xxxxxxxxxxxxx> <c67eed301001180921u6ab1771fq764d51c9ddf92ab9@xxxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
On Mon, Jan 18, 2010 at 9:21 AM, mail ignored <0.bugs.only.0@xxxxxxxxx> wrote:
>> For example, you could try clocksource=acpi, or clocksource=pit. And then
>> check that the 'Platform timer is...' line from Xen boot output changes
>> correspondingly.
>
> checking those now ... will report results in a bit.

both seem to work ...

booting to,

  /xen.gz ... clocksource=acpi ...

then,

 xm dmesg | grep -i timer
  (XEN) ACPI: PM-Timer IO Port: 0x808
  (XEN) ..TIMER: vector=0xF0 apic1=0 pin1=2 apic2=-1 pin2=-1
  (XEN) Platform timer is 3.579MHz ACPI PM Timer
  (XEN) HPET: 4 timers in total, 3 timers will be used for broadcast
  (XEN) mcheck_poll: Machine check polling timer started.

~ 15 minutes, quiet/stable operation @ stratum=2, full reach.

        assID=0 status=0684 leap_none, sync_ntp, 8 events, event_peer/strat_chg,
        version="ntpd 4.2.4p8@xxxxxx Mon Dec 28 17:26:30 UTC 2009 (1)",
        processor="x86_64", system="Linux/2.6.31.8-0.1-xen", leap=00, stratum=2,
        precision=-20, rootdelay=13.970, rootdispersion=26.079, peer=33500,
        refid=216.218.254.202,
        reftime=ceff1d2c.ddbe13c0  Mon, Jan 18 2010  9:47:24.866, poll=6,
        clock=ceff1e07.464f2053  Mon, Jan 18 2010  9:51:03.274, state=4,
        offset=15.245, frequency=24.962, jitter=10.571, noise=17.706,
        stability=7.306
             remote           refid      st t when poll reach   delay   offset  
jitter
        
==============================================================================
        -clock.fmt.he.ne .PPS.            1 u   41   64  377   16.047   20.346  
10.336
        -otc2.psu.edu    130.207.244.240  2 u   39   64  377  100.626   14.538  
 5.387
        +clock.isc.org   .GPS.            1 u   54   64  377   15.174   -0.843  
10.578
        *clock.sjc.he.ne .CDMA.           1 u   26   64  377   13.970   12.255  
 7.051
         zorro.sf-bay.or 216.218.254.202  2 u   31   64  377   16.489   13.730  
 5.781
        +nist1.aol-ca.tr .ACTS.           1 u   15   64  377   14.891    5.947  
14.596

booting to,

  /xen.gz ... clocksource=pit ...

 xm dmesg | grep -i timer
  (XEN) ACPI: PM-Timer IO Port: 0x808
  (XEN) ..TIMER: vector=0xF0 apic1=0 pin1=2 apic2=-1 pin2=-1
  (XEN) Platform timer is 1.193MHz PIT
  (XEN) mcheck_poll: Machine check polling timer started.

~ 20 minutes, quiet/stable operation @ stratum=2, full reach.

        assID=0 status=0654 leap_none, sync_ntp, 5 events, event_peer/strat_chg,
        version="ntpd 4.2.4p8@xxxxxx Mon Dec 28 17:26:30 UTC 2009 (1)",
        processor="x86_64", system="Linux/2.6.31.8-0.1-xen", leap=00, stratum=2,
        precision=-20, rootdelay=16.981, rootdispersion=31.958, peer=63536,
        refid=207.200.81.113,
        reftime=ceff2377.503b4ceb  Mon, Jan 18 2010 10:14:15.313, poll=6,
        clock=ceff240e.fa89c747  Mon, Jan 18 2010 10:16:46.978, state=4,
        offset=9.641, frequency=4.070, jitter=12.958, noise=6.244,
        stability=0.834
             remote           refid      st t when poll reach   delay   offset  
jitter
        
==============================================================================
        +clock.fmt.he.ne .PPS.            1 u   30   64  177   15.250    8.422  
 9.657
        +otc2.psu.edu    147.84.59.145    2 u   33   64  177   99.375   10.359  
 8.906
        +clock.isc.org   .GPS.            1 u   25   64  177   13.060    2.679  
 9.501
        +clock.sjc.he.ne .CDMA.           1 u   22   64  177   15.097   10.608  
 7.866
        +zorro.sf-bay.or 216.218.254.202  2 u   27   64  177   15.082    9.639  
 8.443
        *nist1.aol-ca.tr .ACTS.           1 u   23   64  177   16.981   15.780  
 7.743


seemingly, _nothing_ to do with the kernel, then.  rather overriding
whatever xen's default clocksource is does the trick.

i'll still take a look over longer term @ Dom0, and see if there's any
strangeness in DomU time ...

thanks!

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

<Prev in Thread] Current Thread [Next in Thread>