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

[wangyanan (Y)]

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
>
> .