Re: [Xen-devel] repeatable time jump - Ian Pratt - com.xensource.lists.xen-devel

16 messages in com.xensource.lists.xen-develRe: [Xen-devel] repeatable time jump

From	Sent On	Attachments
David Becker	28 Sep 2004 08:06
David Becker	28 Sep 2004 08:11
Ian Pratt	28 Sep 2004 10:44
David Becker	28 Sep 2004 11:00
Ian Pratt	28 Sep 2004 11:13
David Becker	28 Sep 2004 14:07
Ian Pratt	28 Sep 2004 14:28
David Becker	29 Sep 2004 10:31
Ian Pratt	29 Sep 2004 10:46
David Becker	29 Sep 2004 11:28
Ian Pratt	30 Sep 2004 13:45
David Becker	01 Oct 2004 06:59
Ian Pratt	01 Oct 2004 08:21
David Becker	01 Oct 2004 10:02
Adam Heath	01 Oct 2004 10:25
Peri Hankey	02 Oct 2004 01:35	.diff

Subject:	Re: [Xen-devel] repeatable time jump
From:	Ian Pratt (Ian....@cl.cam.ac.uk)
Date:	09/29/2004 10:46:21 AM
List:	com.xensource.lists.xen-devel

" Close, but not identical. The hwclock time will be written back " periodically.

How periodically?

Once a minute.

" Bizarre. Anything unusual about this machine compared to the " others that are OK?

As of now I am getting repeatable time jumps on 4 of 16, plus another 3 that jump occasionally but not always.

Is the time jump you see on all machines constant? Could you run "while true; date; sleep 1; done" so that we can see what the exact warp is. [it would be very interesting, for example, if it always turned out to be 71 minutes 35 seconds, which is 2^32 usec.]

Is it definitely the act of shutting down the domU that causes the problem? What if you just destroy the domain?

The machines are all IBMs. IBM x330, x335 and HS20 blades. The repeatable hosts have 1GB of mem. THe hosts with only 512 or 256MB ram don't seem to be affected. How could memory size matter?

It seems unlikely that memory size is involved, but the whole thing is weird...

Ian