On Thu, Dec 02, 2010 at 03:27:42PM -0600, W. Michael Petullo wrote:
>> This kernel works as expected with one exception. The
exception has been
>> a nagging problem, but I have not reported it because 1) we are using
>> a research OS in DomU and 2) we are not clear if the problem is in our
>> code, Linux or Xen. But, here are the symptoms:
>> Occasionally (this seems to correlate to network activity between Dom0
>> and DomU), the system becomes unresponsive. I am running the Michael
>> Young kernel at runlevel 3 within Dom0 (very little memory used by
>> applications). Our OS runs in DomU and is constrained to 128MB of
>> memory. When the system is unresponsive, typing a character into a
>> Dom0 console take 2-5 seconds to appear on the screen. Likewise, other
>> activity is extremely slow. As I mentioned, we have not been able to
>> isolate where the problem is. Running, for example, an OpenWrt Linux
>> build in DomU does not have this problem.
> I have seen something similar, though I don't know where the fault
> lies either.
That is somewhat good to hear. I have today solved this problem by running
"xm vcpu-set Domain-0 1." By default, Xen assigned Dom0 all of my cores
(two). Reducing this to one solves the problem for me. I am working on
a better write up that I'll send to fedora-xen and possibly the upstream
Xen mailing list. I have not decided if this is a bug and am having some
discussions locally that may help me formulate a better inquiry.
Usually it's better to use dom0_max_vcpus=1 on the grub xen.gz line.
-- Pasi