Re: [PATCH for-6.2 v5 0/5] hw/arm/virt: Introduce cpu topology support

["wangyanan (Y)" <wangyanan55@huawei.com>]

On 2021/8/24 7:53, Michael S. Tsirkin wrote:
> On Thu, Aug 05, 2021 at 08:39:16PM +0800, Yanan Wang wrote:
>> 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.
> ACPI things:
>
> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Thanks for the reviewing.
> pls merge through ARM tree.
Sure, got it.

Yanan
.
>
>> [1] https://lore.kernel.org/qemu-devel/20210622093413.13360-1-wangyanan55@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-wangyanan55@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-wangyanan55@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
>
> .