linux-kernel - Re: [PATCH] x86/tsc: Use topology_max

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Date: Mon, 18 Mar 2024 09:18:35 +0800
From: Feng Tang <feng.tang@...el.com>
To: "Zhang, Rui" <rui.zhang@...el.com>
CC: "Hansen, Dave" <dave.hansen@...el.com>, "bp@...en8.de" <bp@...en8.de>,
	"x86@...nel.org" <x86@...nel.org>, "peterz@...radead.org"
	<peterz@...radead.org>, "hpa@...or.com" <hpa@...or.com>, "mingo@...hat.com"
	<mingo@...hat.com>, "tglx@...utronix.de" <tglx@...utronix.de>,
	"paulmck@...nel.org" <paulmck@...nel.org>, "longman@...hat.com"
	<longman@...hat.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "dave.hansen@...ux.intel.com"
	<dave.hansen@...ux.intel.com>
Subject: Re: [PATCH] x86/tsc: Use topology_max_packages() to get package
 number

On Sun, Mar 17, 2024 at 08:00:26PM +0800, Zhang, Rui wrote:
> On Fri, 2024-03-15 at 10:58 -0700, Dave Hansen wrote:
> > On 3/15/24 04:26, Feng Tang wrote:
> > > Thomas' recent patchset of refactoring x86 topology code introduces
> > > topology_max_package(), 
> 
> s/topology_max_package/topology_max_packages
> 
> And topology_max_packages() is not new. The patch set actually
> improves/fixes it.

Aha, you are right. Will fix the typo.

Thanks,
Feng

> 
> > 
> > I also did a big *gulp* when I saw this:
> > 
> >         #define topology_max_packages() (__max_logical_packages)
> > 
> > and:
> > 
> > >         /*
> > >          * Today neither Intel nor AMD support heterogeneous
> > > systems so
> > >          * extrapolate the boot cpu's data to all packages.
> > >          */
> > >         ncpus = cpu_data(0).booted_cores *
> > > topology_max_smt_threads();
> > >         __max_logical_packages = DIV_ROUND_UP(total_cpus, ncpus);
> > 
> > Because Intel obviously has heterogeneous systems today.
> > 
> Dave, I think you were checking the old code.
> Please refer to commit 090610ba704a ("x86/cpu/topology: Use topology
> bitmaps for sizing"), which is just merged in this merge window.
> 
> thanks,
> rui