Re: [libvirt] [PATCHv7 00/18] Introduce x86 Cache Monitoring Technology (CMT)

This series of patches and the series already been merged introduce the x86 Cache Monitoring Technology (CMT) to libvirt by interacting with kernel resource control (resctrl) interface. CMT is one of the Intel(R) x86 CPU feature which belongs to the Resource Director Technology (RDT). CMT reports the occupancy of the last level cache, which is shared by all CPU cores.

In the v1 series, an original and complete feature for CMT was introduced The v2 and v3 patches address the feature for the host capability of CMT. v4 is addressing the feature for monitoring VM vcpu thread set cache occupancy and reporting it through a virsh command. We have serval discussion about the enabling of CMT, please refer to following links for the RFCs. RFCv3 https://www.redhat.com/archives/libvir-list/2018-August/msg01213.html RFCv2 https://www.redhat.com/archives/libvir-list/2018-July/msg00409.html https://www.redhat.com/archives/libvir-list/2018-July/msg01241.html RFCv1 https://www.redhat.com/archives/libvir-list/2018-June/msg00674.html And the merged commits are list as below, for host capability of CMT. 6af8417415508c31f8ce71234b573b4999f35980 8f6887998bf63594ae26e3db18d4d5896c5f2cb4 58fcee6f3a2b7e89c21c1fb4ec21429c31a0c5b8 12093f1feaf8f5023dcd9d65dff111022842183d a5d293c18831dcf69ec6195798387fbb70c9f461 1. About reason why CMT is necessary in libvirt? The perf events of 'CMT, MBML, MBMT' have been phased out since Linux kernel commit c39a0e2c8850f08249383f2425dbd8dbe4baad69, in libvirt the perf based cmt,mbm will not work with the latest linux kernel. These patches add CMT feature to libvirt through kernel resctrlfs interface. 2 Create cache monitoring group (cache monitor). The main interface for creating monitoring group is through XML file. The proposed configuration is like: <cputune> <cachetune vcpus='1'> <cache id='0' level='3' type='code' size='7680' unit='KiB'/> <cache id='1' level='3' type='data' size='3840' unit='KiB'/> + <monitor level='3' vcpus='1'/> </cachetune> <cachetune vcpus='4-7'> + <monitor level='3' vcpus='4-6'/> </cachetune> </cputune> In above XML, created 2 cache resctrl allocation groups and 2 resctrl monitoring groups. The changes of cache monitor will be effective in next booting of VM. 2 Show CMT result through command 'domstats' Adding the interface in qemu to report this information for resource monitor group through command 'virsh domstats --cpu-total'. Below is a typical output: # virsh domstats 1 --cpu-total Domain: 'ubuntu16.04-base' ... cpu.cache.monitor.count=2 cpu.cache.monitor.0.name=vcpus_1 cpu.cache.monitor.0.vcpus=1 cpu.cache.monitor.0.bank.count=2 cpu.cache.monitor.0.bank.0.id=0 cpu.cache.monitor.0.bank.0.bytes=4505600 cpu.cache.monitor.0.bank.1.id=1 cpu.cache.monitor.0.bank.1.bytes=5586944 cpu.cache.monitor.1.name=vcpus_4-6 cpu.cache.monitor.1.vcpus=4,5,6 cpu.cache.monitor.1.bank.count=2 cpu.cache.monitor.1.bank.0.id=0 cpu.cache.monitor.1.bank.0.bytes=17571840 cpu.cache.monitor.1.bank.1.id=1 cpu.cache.monitor.1.bank.1.bytes=29106176 Changes in v7: - Add several lines removed by mistake. Changes in v6: - Addressing John's review comments for v5. - Removed and cleaned the concepts of 'default allocation' and 'default monitor'. - qemu: virsh domstats --cpu-total output for CMT, add identifier 'monitor' for each itm. Changes in v5: - qemu: Setting up vcpu and adding pids to resctrl monitor groups during re-connection. - Add the document for domain configuration related to resctrl monitor. Changes in v4: v4 is addressing the feature for monitoring VM vcpu thread set cache occupancy and reporting it through a virsh command. - Introduced resctrl default allocation - Introduced resctrl monitor and default monitor Changes in v3: - Addressed John Ferlan's review. - Typo fixed. - Removed VIR_ENUM_DECL(virMonitor); Changes in v2: - Introduced MBM capability. - Capability layout changed * Moved <monitor> from cahe <bank> to <cache> * Renamed <Threshold> to <reuseThreshold> - Document for 'reuseThreshold' changed. - Introduced API virResctrlInfoGetMonitorPrefix - Added more tests, covering standalone CMT, fake new feature. - Creating CMT resource control group will be subsequent job. Wang Huaqiang (18): docs,util: Refactor schemas and virresctrl to support optional cache util: Introduce resctrl monitor for CMT util: Refactor code for determining allocation path util: Add interface to determine monitor path util: Refactor code for adding PID to the resource group util: Add interface for adding PID to the monitor util: Refactor code for creating resctrl group util: Add interface for creating monitor group util: Add more interfaces for resctrl monitor conf: Remove virDomainResctrlAppend and introduce virDomainResctrlNew conf: move virResctrlAllocIsEmpty to a place a litter lower conf: Introduce cache monitor element in cachetune qemu: enable resctrl monitor in qemu util: Add function for checking if monitor is running conf: Add 'id' to virDomainResctrlDef qemu: refactor qemuDomainGetStatsCpu qemu: Report cache occupancy (CMT) with domstats qemu: Setting up vcpu and adding pids to resctrl monitor groups during reconnection docs/formatdomain.html.in | 30 +- docs/schemas/domaincommon.rng | 14 +- src/conf/domain_conf.c | 310 ++++++++++-- src/conf/domain_conf.h | 12 + src/libvirt-domain.c | 9 + src/libvirt_private.syms | 11 + src/qemu/qemu_driver.c | 270 +++++++++- src/qemu/qemu_process.c | 69 ++- src/util/virresctrl.c | 560 +++++++++++++++++++-- src/util/virresctrl.h | 49 ++ tests/genericxml2xmlindata/cachetune-cdp.xml | 3 + .../cachetune-colliding-monitor.xml | 30 ++ tests/genericxml2xmlindata/cachetune-small.xml | 7 + tests/genericxml2xmltest.c | 2 + 14 files changed, 1283 insertions(+), 93 deletions(-) create mode 100644 tests/genericxml2xmlindata/cachetune-colliding-monitor.xml