Hi, This series is a new version of [0] recently posted by Ying Fang to introduce cpu topology support for ARM platform. I have taken over his work about this now, thanks for his contribution.
Description: An accurate cpu topology may help improve the cpu scheduler's decision making when dealing with multi-core system. So cpu topology description is helpful to provide guest with the right view. Dario Faggioli's talk in [1] also shows the virtual topology could have impact on scheduling performace. Thus this patch series introduces cpu topology support for ARM platform. This series originally comes from Andrew Jones's patches [2], but with some re-arrangement. Thanks for Andrew's contribution. In this series, both fdt and ACPI PPTT table are introduced to present cpu topology to the guest. And a new function virt_smp_parse() not like the default smp_parse() is introduced, which prefers cores over sockets. [0] https://patchwork.kernel.org/project/qemu-devel/cover/20210225085627.2263-1-fangyi...@huawei.com/ [1] https://kvmforum2020.sched.com/event/eE1y/virtual-topology-for-virtual-machines-friend-or-foe-dario-faggioli-suse [2] https://github.com/rhdrjones/qemu/commit/ecfc1565f22187d2c715a99bbcd35cf3a7e428fa Test results: After applying this patch series, launch a guest with virt-6.0 and cpu topology configured with: -smp 96,sockets=2,clusters=6,cores=4,threads=2, VM's cpu topology description shows as below. Architecture: aarch64 Byte Order: Little Endian CPU(s): 96 On-line CPU(s) list: 0-95 Thread(s) per core: 2 Core(s) per socket: 24 Socket(s): 2 NUMA node(s): 1 Vendor ID: 0x48 Model: 0 Stepping: 0x1 BogoMIPS: 200.00 NUMA node0 CPU(s): 0-95 --- Changelogs: v1->v2: - Address Andrew Jones's comments - Address Michael S. Tsirkin's comments - Pick up one more patch(patch#6) of Andrew Jones - Rebased on v6.0.0-rc2 release --- Andrew Jones (3): device_tree: Add qemu_fdt_add_path hw/arm/virt: DT: Add cpu-map hw/arm/virt: Replace smp_parse with one that prefers cores Yanan Wang (2): hw/acpi/aml-build: Add processor hierarchy node structure hw/arm/virt-acpi-build: Add PPTT table Ying Fang (1): hw/arm/virt-acpi-build: Distinguish possible and present cpus hw/acpi/aml-build.c | 27 ++++++++ hw/arm/virt-acpi-build.c | 77 ++++++++++++++++++++-- hw/arm/virt.c | 120 ++++++++++++++++++++++++++++++++++- include/hw/acpi/aml-build.h | 4 ++ include/hw/arm/virt.h | 1 + include/sysemu/device_tree.h | 1 + softmmu/device_tree.c | 45 ++++++++++++- 7 files changed, 268 insertions(+), 7 deletions(-) -- 2.19.1