linux-kernel - Re: [PATCH] x86/ACPI/State: Optimize C3 entry on AMD CPUs

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Message-ID: <1f4a2197-2559-49fb-0f59-ae3365be9d05@amd.com>
Date:   Thu, 23 Sep 2021 22:42:13 -0700
From:   "Sharma, Deepak" <deesharm@....com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Deepak Sharma <deepak.sharma@....com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        "open list:SUSPEND TO RAM" <linux-pm@...r.kernel.org>,
        "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" 
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86/ACPI/State: Optimize C3 entry on AMD CPUs


On 9/22/2021 5:47 AM, Rafael J. Wysocki wrote:
> On Wed, Sep 22, 2021 at 5:50 AM Sharma, Deepak <deesharm@....com> wrote:
>> Hi Rafael,
>>
>> On 9/1/2021 5:45 AM, Rafael J. Wysocki wrote:
>>> On Wed, Sep 1, 2021 at 4:14 AM Deepak Sharma <deesharm@....com> wrote:
>>>> On 8/25/21 11:07 AM, Rafael J. Wysocki wrote:
>>>>> On Thu, Aug 19, 2021 at 2:43 AM Deepak Sharma <deepak.sharma@....com> wrote:
>>>>>> AMD CPU which support C3 shares cache. Its not necessary to flush the
>>>>>> caches in software before entering C3. This will cause performance drop
>>>>>> for the cores which share some caches. ARB_DIS is not used with current
>>>>>> AMD C state implementation. So set related flags correctly.
>>>>>>
>>>>>> Signed-off-by: Deepak Sharma <deepak.sharma@....com>
>>>>> Applied as 5.15 material under the edited subject "x86: ACPI: cstate:
>>>>> Optimize C3 entry on AMD CPUs", thanks!
>>>> I might need to send subsequent patch for this. Can you please point me
>>>> to git and branch where this has been merged.
>>> git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next
>> Still I am not able to see this patch merged on linux-next branch.
> It was there, but got dropped before the merge window due to the
> unclear next steps.
>
> I'd rather see this resent along with the subsequent patch you were
> talking about.
Thanks for the clarification. I will resend patch with subsequent 
changes which will have support for zen onward CPU's.