RE: [PATCH v3 1/2] cpu/smt: add a notifier to notify the SMT changes

[Yang, WenYou]

[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 game for some AMD APUs with SMT enabled/disabled.

When change the SMT state on the fly through " echo on/off > /sys/devices/system/cpu/smt/control", the kernel needs to send a message to notify PMFW to adjust a variable's value, which impacts the performance.

Best Regards,
Wenyou

> -----Original Message-----
> From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Sent: Wednesday, March 29, 2023 3:10 PM
> To: Yang, WenYou <WenYou.Yang@xxxxxxx>
> Cc: Deucher, Alexander <Alexander.Deucher@xxxxxxx>; Koenig, Christian
> <Christian.Koenig@xxxxxxx>; Pan, Xinhui <Xinhui.Pan@xxxxxxx>; Quan, Evan
> <Evan.Quan@xxxxxxx>; Limonciello, Mario <Mario.Limonciello@xxxxxxx>;
> bp@xxxxxxx; jpoimboe@xxxxxxxxxx; Phillips, Kim <kim.phillips@xxxxxxx>;
> tglx@xxxxxxxxxxxxx; Yuan, Perry <Perry.Yuan@xxxxxxx>; Liang, Richard qi
> <Richardqi.Liang@xxxxxxx>; Li, Ying <YING.LI@xxxxxxx>; Liu, Kun
> <Kun.Liu2@xxxxxxx>; gpiccoli@xxxxxxxxxx; amd-gfx@xxxxxxxxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v3 1/2] cpu/smt: add a notifier to notify the SMT changes
> 
> Caution: This message originated from an External Source. Use proper caution
> when opening attachments, clicking links, or responding.
> 
> 
> On Wed, Mar 29, 2023 at 09:51:48AM +0800, Wenyou Yang wrote:
> > Add the notifier chain to notify the cpu SMT status changes
> >
> 
> 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 this I can't
> tell you if that matters or not :/