RE: [RFC] timer_interrupt: Avoid device timeouts by freezing time if system froze

From: Luck, Tony <tony.luck_at_intel.com>
Date: 2005-09-10 08:36:01
>I am aware of at least two ia64 virtualization systems
>that rely on the existing behavior to compensate for
>the fact that one guest linux may be inactive while another
>is active.  This isn't to say that another solution
>couldn't be found, but just turning off the existing
>behavior doesn't seem like a good alternative. 

There must be some minimum frequency at which a hypervisor
allows a guest to run in order for it to operate normally
[e.g. a guest that gets no cpu time for several seconds at
a stretch will experience network time-outs with external
systems that it is unable to supply with "keep-alive" packets].

I'm not sure what that minimum frequency is, but I expect that
it may be contrained by some of the shorter TCP timeouts.  I
think that there is one around the 200 milli-second mark.

So possibly a hypervisor that starves a guest for long enough
to trigger Christoph's patch has other problems than just
keeping time correct in the guest.

-Tony
-
To unsubscribe from this list: send the line "unsubscribe linux-ia64" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Received on Sat Sep 10 08:36:43 2005

This archive was generated by hypermail 2.1.8 : 2005-09-10 08:36:51 EST