>>>> 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.

So, is this a known "issue." Is it typically best practice to limit Dom0 to
one core? I've seen systems where this is not a problem (dom0_max_vcpus=n
works fine, where n is the number of cores) and others where it is. Why
would this be?


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