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

On Tue, Dec 23, 2014 at 03:47:35PM +0000, Andrew Cooper wrote:
> 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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