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

[Yang, WenYou]

[AMD Official Use Only - General]



> -----Original Message-----
> From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Sent: Wednesday, March 29, 2023 4:50 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@xxxxxxxxx; 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
> 
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> 
> On Wed, Mar 29, 2023 at 07:23:29AM +0000, Yang, WenYou wrote:
> > [AMD Official Use Only - General]
> 
> ^^^ that has no business being in a public email.
> 
> > 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.
> 
> When top posting I normally ignore the email. When not wrapping email I
> typically get cranky. You 'win' *3* 'I cannot use email' trophies in a singly try.
> Surely AMD has a HOWTO somewhere you can read?

Yes. It is my fault. Sorry.

> 
> So what do you want to have happen when someone goes and manually offlines
> all the SMT siblings using /sys/devices/system/cpu/cpu*/online
> ?

I don't consider this situation.  Any suggestions will be deeply appreciated.

> 
> I'm thinking that wants the same PMFW (whatever the heck that is) notification
> change done, right?
> 
> If the answer is "yes", then your patch does not meet the goals and is
> inadequate.

Yes.  Need to improve.

Thank you.
Wenyou