Re: [libvirt] [RFC PATCHv2 00/10] x86 RDT Cache Monitoring Technology (CMT)

This is the V2 of RFC and the POC source code for introducing x86 RDT CMT feature, thanks Martin Kletzander for his review and constructive suggestion for V1. This series is trying to provide the similar functions of the perf event based CMT, MBMT and MBML features in reporting cache occupancy, total memory bandwidth utilization and local memory bandwidth utilization information in livirt. Firstly we focus on cmt. x86 RDT Cache Monitoring Technology (CMT) provides a medthod to track the cache occupancy information per CPU thread. We are leveraging the implementation of kernel resctrl filesystem and create our patches on top of that. Describing the functionality from a high level: 1. Extend the output of 'domstats' and report CMT inforamtion. Comparing with perf event based CMT implementation in libvirt, this series extends the output of command 'domstat' and reports cache occupancy information like these: <pre> [root@dl-c200 libvirt]# virsh domstats vm3 --cpu-resource Domain: 'vm3' cpu.cacheoccupancy.vcpus_2.value=4415488 cpu.cacheoccupancy.vcpus_2.vcpus=2 cpu.cacheoccupancy.vcpus_1.value=7839744 cpu.cacheoccupancy.vcpus_1.vcpus=1 cpu.cacheoccupancy.vcpus_0,3.value=53796864 cpu.cacheoccupancy.vcpus_0,3.vcpus=0,3 </pre> The vcpus have been arragned into three monitoring groups, these three groups cover vcpu 1, vcpu 2 and vcpus 0,3 respectively. Take an example, the 'cpu.cacheoccupancy.vcpus_0,3.value' reports the cache occupancy information for vcpu 0 and vcpu 3, the 'cpu.cacheoccupancy.vcpus_0,3.vcpus' represents the vcpu group information. To address Martin's suggestion "beware as 1-4 is something else than 1,4 so you need to differentiate that.", the content of 'vcpus' (cpu.cacheoccupancy.<groupname>.vcpus=xxx) has been specially processed, if vcpus is a continous range, e.g. 0-2, then the output of cpu.cacheoccupancy.vcpus_0-2.vcpus will be like 'cpu.cacheoccupancy.vcpus_0-2.vcpus=0,1,2' instead of 'cpu.cacheoccupancy.vcpus_0-2.vcpus=0-2'. Please note that 'vcpus_0-2' is a name of this monitoring group, could be specified any other word from the XML configuration file or lively changed with the command introduced in following part.