[libvirt] [RFCv2 PATCH 0/5] Introduce RDT memory bandwidth allocation support

[bing.niu at intel.com]

From: Bing Niu <bing.niu at intel.com>

This series is to introduce RDT memory bandwidth allocation support by extending
current virresctrl implementation.

The Memory Bandwidth Allocation (MBA) feature provides indirect and approximate
control over memory bandwidth available per-core. This feature provides a method to
control applications which may be over-utilizing bandwidth relative to their priority
in environments such as the data-center. The details can be found in Intel's SDM 17.19.7.
Kernel supports MBA through resctrl file system same as CAT. Each resctrl group have a
MB parameter to control how much memory bandwidth it can utilize in unit of percentage.

In this series, MBA is enabled by enhancing existing virresctrl implementation. The
policy employed for MBA is similar with CAT: The sum of each MBA group's bandwidth
dose not exceed 100%. 

The enhancement of virresctrl include two parts:

Part 1:  Add two new structures virResctrlInfoMB and virResctrlAllocMB for collecting
         host system MBA capability and domain memory bandwidth allocation. Those two
         structures are the extension of existing virResctrlInfo and virResctrlAlloc. With
         them, virresctrl framework can support MBA and CAT concurrently. Each virResctrlAlloc
         represent a resource allocation including CAT, or MBA, or CAT&MBA. The policy of MBA is
         that: total memory bandwidth of each resctrl group, created by virresctrl, does not
         exceed to 100%.

Part 2:  On XML part, add new elements to host capabilities query and domain allocation to support
         memory bandwidth allocation.
     ----------------------------------------------------------------------------------------------  
         For host capabilities XML, new XML format like below example,
           <host>
            .....
             <memory>
               <node id='0' cpus='0-19'>
                 <control granularity='10' min ='10' maxAllocs='8'/>
               </node>
             </memory>
           </host>
          
           granularity --- memory bandwidth granularity
           min         --- minimum memory bandwidth allowed
           maxAllocs   --- maximum concurrent memory bandwidth allocation allowed.

     ----------------------------------------------------------------------------------------------  
         For domain XML, new format as below example
           <domain type='kvm' id='2'>
             ...... 
             <cputune>
               ......
               <shares>1024</shares>
               <memorytune vcpus='0-1'>
                 <node id='0' bandwidth='20'/>
               </memorytune>
             </cputune>
             ......
           </domain>

          id         --- node where memory bandwidth allocation will happen
          bandwidth  --- bandwidth allocated in percentage

     ----------------------------------------------------------------------------------------------  

Changelog:
        v1->v2:
            Jano's comment: 1. put renaming parts into separated patches.
                            2. set the initial return value as -1.
                            3. using full name in structure definition.
                            4. do not use VIR_CACHE_TYPE_LAST for memory bandwidth allocation formatting.
            
            Pavel's comment: 1. add host capabilities XML for memory bandwidth allocation.
                             2. do not mix use cachetune section in XML for memory bandwidth allocation in
                                domain XML. define a dedicated one for memory bandwidth allocation.

Bing Niu (5):
  util: Rename and packing parts of virresctrl
  util: Add memory bandwidth support to resctrl
  conf: rename cachetune to restune
  conf: Introduce  cputune/memorytune to support memory bandwidth
    allocation
  conf: add memory bandwidth allocation capability of host

 src/conf/capabilities.c  | 112 +++++++++++
 src/conf/capabilities.h  |  11 ++
 src/conf/domain_conf.c   | 304 ++++++++++++++++++++++++++---
 src/conf/domain_conf.h   |  10 +-
 src/libvirt_private.syms |   4 +-
 src/qemu/qemu_process.c  |  18 +-
 src/util/virresctrl.c    | 496 ++++++++++++++++++++++++++++++++++++++++++++---
 src/util/virresctrl.h    |  35 +++-
 8 files changed, 918 insertions(+), 72 deletions(-)

-- 
2.7.4