another bug: system time change

[Wolfgang Hennerbichler]

On Apr 9, 2010, at 10:49 , Ondrej Zajicek wrote:

> On Fri, Apr 09, 2010 at 10:22:05AM +0200, Wolfgang Hennerbichler wrote:
>> Hi Ondrejs, 
>> 
>> I think I found another bug. For some mysterious reason our system time jumped forward (more than 30.000 seconds) on one of our route-servers. I don't know why this happened, but I suspect a broken ntp server could have caused this. Nevetheless, this was reason enough for BIRD to drop the BGP peerings: 
>> 
> 
>> You see the log-entries from the wtachdog, which is run every minute,
>> all of a sudden the time jumps to 10:08 UTC, and BIRD brings down BGP
>> sessions. Are the session hold timers dependent on the system time? 
> 
> That is really strange. On Linux 2.6, we use monotonic timers, which
> shouldn't be affected by system time change. If monotonic timers are not
> available (on Linux 2.4), we use system time but we detect time jumps
> and ignore them.

Hm. Now this is strange indeed. I run linux 2.6.33.1 (amd64) - but it is a virtualized host (with xen). Maybe it was xen's fault, but the logs don't reveal much as you see. Hm. this sucks. 

> 
> -- 
> Elen sila lumenn' omentielvo
> 
> Ondrej 'SanTiago' Zajicek (email: santiago at crfreenet.org)
> OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
> "To err is human -- to blame it on a computer is even more so."

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