From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Jan Beulich" <jbeulich@suse.com>
Subject: Re: Xen Platform QoS design discussion
Date: Fri, 30 May 2014 12:15:11 +0100
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>>> "Xu, Dongxiao" <dongxiao.xu@intel.com> 05/30/14 9:52 AM >>>
> From: Jan Beulich [mailto:jbeulich@suse.com]
>> Question is whether this mechanism (which I'd like to be done so it can also
>> later get added support for e.g. port I/O: see Linux'es dcdbas_smi_request()
>> for where this might be useful) should become a sysctl op or - to be
>> easily usable by the kernel too - a platform one.
>
>For CQM, this MSR access hypercall may be somewhat specific, because it
>requires one MSR write and one MSR read, which cannot be split into two
>separate hypercalls to avoid preemption in the middle.

Sure - you'd need a flag to suppress preemption between two specific (batched)
operations.

Jan