On 2024/12/26 17:23, Shrikanth Hegde wrote:

On 12/20/24 13:23, Yicong Yang wrote:

quoted

From: Yicong Yang <yangyicong@hisilicon.com>

The core CPU control framework supports runtime SMT control which
is not yet supported on arm64. Besides the general vulnerabilities
concerns we want this runtime control on our arm64 server for:

- better single CPU performance in some cases
- saving overall power consumption

EAS is disabled when SMT is present.
I am curious to know how power saving happens here.

EAS shouldn't work on non-asymmetic systems, so it's not the case here.
System wide power consumption comes down from the CPU offlining here.

Thanks.

quoted

This patchset implements it in the following aspects:

- Provides a default topology_is_primary_thread()
- support retrieve SMT thread number on OF based system
- support retrieve SMT thread number on ACPI based system
- select HOTPLUG_SMT for arm64

Tests has been done on our ACPI based arm64 server and on ACPI/OF\
based QEMU VMs.

.