From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Chen, Tiejun" <tiejun.chen@intel.com>
Subject: Re: [PATCH] xen/domctl: lower loglevel of
 XEN_DOMCTL_memory_mapping
Date: Fri, 11 Sep 2015 08:44:50 +0800
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>> Right, that's one of the things that would need taking care of.
>> (Whether enforcing an upper limit is actually needed I'm not
>> sure - we generally allow the admin to shoot himself in the foot
>> if he wants to. And whether the lower limit should be 64 instead
>> of just ensuring the limit is not zero is another question.)
>
> 64 was semi-arbitrary  - it ended up giving good latency on
> highly scalar machines (8 socket). Higher numbers ended up
> affecting the latency.
>
> But higher numbers on small socket machines were OK.
> (As they do not have 8 IOMMU VT-d chipsets all potentially
> flodding the QPI with serialized cache flushes).
>>

So we should make this range [8, <Its up to the user>] here, but 64 by 
default. Right?

Thanks
Tiejun