kern/153620: Xen guest system clock drifts in AWS EC2 (FreeBSD 9.0-CURRENT i386 T1-micro)

[Greg Holmberg]

The following reply was made to PR kern/153620; it has been noted by GNATS.

From: Greg Holmberg <fbsd-9.0-aws-ec2-1293964000 at holmberg.to>
To: FreeBSD PR kern/153620 <bug-followup at FreeBSD.org>
Cc:  
Subject: Re: kern/153620: Xen guest system clock drifts in AWS EC2 (FreeBSD
 9.0-CURRENT i386 T1-micro)
Date: Wed, 5 Jan 2011 17:32:53 +0100

 The latest AMI (FreeBSD 9.0-CURRENT @ 2011-01-04) still drops time in chunks. It loses time in multiples of 2200 seconds while idle.
 
 The clock in the latest AMIs and older AMIs also drifts. Without some kind of external correction, it runs slightly slower, losing time at a rate of a little less than one second every 24 hours.
 
 In the 2011-01-01 and 2011-01-04 AMIs, a single ping from a remote host once every thirty minutes keeps an otherwise idle VM awake enough to prevent any time from being lost in chunks.
 
 In the latest AMIs and older AMIs, no amount of system activity or interrupts seems to prevent, aggravate, or change the rate of gradual clock drift.
 
 Regards,
 
 Greg Holmberg