Hi, This is a new version (v5) of the series [1] that I posted to introduce support for generating cpu topology descriptions to virt machine guest.
Once the view of an accurate virtual cpu topology is provided to guest, with a well-designed vCPU pinning to the pCPU we may get a huge benefit, e.g., the scheduling performance improvement. See Dario Faggioli's research and the related performance tests in [2] for reference. This patch series introduces cpu topology support for ARM platform. Both cpu-map in DT and ACPI PPTT table are introduced to store the topology information. And we only describe the topology information to 6.2 and newer virt machines, considering compatibility. [1] https://lore.kernel.org/qemu-devel/20210622093413.13360-1-wangyana...@huawei.com/ [2] https://kvmforum2020.sched.com/event/eE1y/virtual-topology-for-virtual-machines -friend-or-foe-dario-faggioli-suse Some tests: 1) -smp 16,sockets=2,cores=4,threads=2,maxcpus=16 lscpu: Architecture: aarch64 Byte Order: Little Endian CPU(s): 16 On-line CPU(s) list: 0-15 Thread(s) per core: 2 Core(s) per socket: 4 Socket(s): 2 NUMA node(s): 1 Vendor ID: ARM Model: 2 Model name: Cortex-A72 Stepping: r0p2 BogoMIPS: 100.00 NUMA node0 CPU(s): 0-15 cat /sys/devices/system/cpu/present --> 0-15 cat /sys/devices/system/cpu/possible --> 0-15 2) -smp 8,sockets=2,cores=4,threads=2,maxcpus=16 lscpu: Architecture: aarch64 Byte Order: Little Endian CPU(s): 8 On-line CPU(s) list: 0-7 Thread(s) per core: 2 Core(s) per socket: 4 Socket(s): 1 NUMA node(s): 1 Vendor ID: ARM Model: 2 Model name: Cortex-A72 Stepping: r0p2 BogoMIPS: 100.00 NUMA node0 CPU(s): 0-7 cat /sys/devices/system/cpu/present --> 0-7 cat /sys/devices/system/cpu/possible --> 0-7 --- Changelogs: v4->v5: - drop the added -smp "expose=on|off" parameter and only describe topology for 6.2 and newer machines - rebased the code on patch series [3] which has introduced some fix and improvement for smp parsing - [3]: https://lore.kernel.org/qemu-devel/20210803080527.156556-1-wangyana...@huawei.com/ v3->v4: - add new -smp parameter "expose=on|off" for users to enable/disable the feature - add stricter -smp cmdline parsing rules on "expose=on" case - move build_pptt to generic aml-build.c - add default cluster node in the cpu-map - rebase on top of latest upstream master - v3: https://lore.kernel.org/qemu-devel/20210516102900.28036-1-wangyana...@huawei.com/ v2->v3: - address comments from David, Philippe, and Andrew. Thanks! - split some change into separate commits for ease of review - adjust parsing rules of virt_smp_parse to be more strict (after discussion with Andrew) - adjust author credit for the patches v1->v2: - Address Andrew Jones's comments - Address Michael S. Tsirkin's comments --- Andrew Jones (2): hw/arm/virt: Add cpu-map to device tree hw/acpi/aml-build: Generate PPTT table Yanan Wang (3): hw/arm/virt: Only describe cpu topology to guest since virt 6.2 device_tree: Add qemu_fdt_add_path hw/acpi/aml-build: Add Processor hierarchy node structure hw/acpi/aml-build.c | 76 ++++++++++++++++++++++++++++++++++++ hw/arm/virt-acpi-build.c | 8 +++- hw/arm/virt.c | 62 ++++++++++++++++++++++++----- include/hw/acpi/aml-build.h | 7 ++++ include/hw/arm/virt.h | 4 +- include/sysemu/device_tree.h | 1 + softmmu/device_tree.c | 44 ++++++++++++++++++++- 7 files changed, 188 insertions(+), 14 deletions(-) -- 2.19.1
