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

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.


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