Re: [Xen-devel] [PATCH 0/4] enable Memory Bandwidth Monitoring (MBM) for VMs

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 23/12/2014 08:54, Chao Peng wrote:
> Intel Memory Bandwidth Monitoring(MBM) is a new hardware feature
> which builds on the CMT infrastructure to allow monitoring of system
> memory bandwidth. Event codes are provided to monitor both "total"
> and "local" bandwidth, meaning bandwidth over QPI and other external
> links can be monitored.
>
> For XEN, MBM is used to monitor memory bandwidth for VMs. Due to its
> dependency on CMT, the software also makes use of most of CMT codes.
> Actually, besides introducing two additional events and some cpuid
> feature bits, there are no extra changes compared to cache occupancy
> monitoring in CMT. Due to this, CMT should be enabled first to use
> this feature.
>
> For interface changes, the patch serial only introduces a new command
> "XEN_SYSCTL_PSR_CMT_get_l3_event_mask" which exposes MBM feature
> capability to user space and introduces two additional options for
> "xl psr-cmt-show":
> total_mem_bandwidth:     Show total memory bandwidth
> local_mem_bandwidth:     Show local memory bandwidth
>
> The usage flow keeps the same with CMT.
>
> Chao Peng (4):
>    x86: expose CMT L3 event mask to user space
>    tools: libxc: add routine to get CMT L3 event mask
>    tools: libxl: code preparation for MBM
>    tools: add total/local memory bandwith monitoring
Please can you add a note about MBM in the command line documentation, 
beside the CMT information.
~Andrew

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