linux-kernel - Re: [PATCH v10 0/4] Support SMT control on arm64

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <d0e73e64-cdf7-443b-a8e3-7c1f25533000@linux.ibm.com>
Date: Thu, 26 Dec 2024 14:53:32 +0530
From: Shrikanth Hegde <sshegde@...ux.ibm.com>
To: Yicong Yang <yangyicong@...wei.com>
Cc: linuxppc-dev@...ts.ozlabs.org, x86@...nel.org,
        linux-kernel@...r.kernel.org, morten.rasmussen@....com,
        msuchanek@...e.de, gregkh@...uxfoundation.org, rafael@...nel.org,
        jonathan.cameron@...wei.com, prime.zeng@...ilicon.com,
        linuxarm@...wei.com, yangyicong@...ilicon.com, xuwei5@...wei.com,
        guohanjun@...wei.com, catalin.marinas@....com, will@...nel.org,
        sudeep.holla@....com, tglx@...utronix.de, peterz@...radead.org,
        mpe@...erman.id.au, linux-arm-kernel@...ts.infradead.org,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        pierre.gondois@....com, dietmar.eggemann@....com
Subject: Re: [PATCH v10 0/4] Support SMT control on arm64



On 12/20/24 13:23, Yicong Yang wrote:
> From: Yicong Yang <yangyicong@...ilicon.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.

> 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.
>