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From:   "Yang, WenYou" <WenYou.Yang@amd.com>
To:     Peter Zijlstra <peterz@infradead.org>
CC:     "Deucher, Alexander" <Alexander.Deucher@amd.com>,
        "Koenig, Christian" <Christian.Koenig@amd.com>,
        "Pan, Xinhui" <Xinhui.Pan@amd.com>,
        "Quan, Evan" <Evan.Quan@amd.com>,
        "Limonciello, Mario" <Mario.Limonciello@amd.com>,
        "bp@suse.de" <bp@suse.de>,
        "jpoimboe@kernel.org" <jpoimboe@kernel.org>,
        "Phillips, Kim" <kim.phillips@amd.com>,
        "tglx@linutronix.de" <tglx@linutronix.de>,
        "Yuan, Perry" <Perry.Yuan@amd.com>,
        "Liang, Richard qi" <Richardqi.Liang@amd.com>,
        "Li, Ying" <YING.LI@amd.com>, "Liu, Kun" <Kun.Liu2@amd.com>,
        "gpiccoli@igalia.com" <gpiccoli@igalia.com>,
        "amd-gfx@lists.freedesktop.org" <amd-gfx@lists.freedesktop.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v3 1/2] cpu/smt: add a notifier to notify the SMT changes
Thread-Topic: [PATCH v3 1/2] cpu/smt: add a notifier to notify the SMT changes
Thread-Index: AQHZYeESu1Z/BgjKTUGFWIVG6kMXya8RV0EAgAAB2QA=
Date:   Wed, 29 Mar 2023 07:23:29 +0000
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References: <20230329015149.870132-1-WenYou.Yang@amd.com>
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[AMD Official Use Only - General]

Hi Peter,

Thank you for your review.

The purpose of the patch set is to improve the performance when playing gam=
e for some AMD APUs with SMT enabled/disabled.

When change the SMT state on the fly through " echo on/off > /sys/devices/s=
ystem/cpu/smt/control", the kernel needs to send a message to notify PMFW t=
o adjust a variable's value, which impacts the performance.

Best Regards,
Wenyou

> -----Original Message-----
> From: Peter Zijlstra <peterz@infradead.org>
> Sent: Wednesday, March 29, 2023 3:10 PM
> To: Yang, WenYou <WenYou.Yang@amd.com>
> Cc: Deucher, Alexander <Alexander.Deucher@amd.com>; Koenig, Christian
> <Christian.Koenig@amd.com>; Pan, Xinhui <Xinhui.Pan@amd.com>; Quan, Evan
> <Evan.Quan@amd.com>; Limonciello, Mario <Mario.Limonciello@amd.com>;
> bp@suse.de; jpoimboe@kernel.org; Phillips, Kim <kim.phillips@amd.com>;
> tglx@linutronix.de; Yuan, Perry <Perry.Yuan@amd.com>; Liang, Richard qi
> <Richardqi.Liang@amd.com>; Li, Ying <YING.LI@amd.com>; Liu, Kun
> <Kun.Liu2@amd.com>; gpiccoli@igalia.com; amd-gfx@lists.freedesktop.org;
> linux-kernel@vger.kernel.org
> Subject: Re: [PATCH v3 1/2] cpu/smt: add a notifier to notify the SMT cha=
nges
>=20
> Caution: This message originated from an External Source. Use proper caut=
ion
> when opening attachments, clicking links, or responding.
>=20
>=20
> On Wed, Mar 29, 2023 at 09:51:48AM +0800, Wenyou Yang wrote:
> > Add the notifier chain to notify the cpu SMT status changes
> >
>=20
> Why!?!? What's the purpose of all this? IIRC this doesn't trigger if you =
manually
> disable all the siblings. And because you didn't tell us why you need thi=
s I can't
> tell you if that matters or not :/