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From: Thomas Gleixner <tglx@linutronix.de>
To: "Zhang, Rui" <rui.zhang@intel.com>, "linux-kernel@vger.kernel.org"
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Subject: Re: [patch v2 25/30] x86/cpu/topology: Use topology logical mapping
 mechanism
In-Reply-To: <5024c989133441608592ef86bc78ca2573bcc728.camel@intel.com>
References: <20240118123127.055361964@linutronix.de>
 <20240118123649.971809766@linutronix.de>
 <5024c989133441608592ef86bc78ca2573bcc728.camel@intel.com>
Date: Mon, 12 Feb 2024 17:21:37 +0100
Message-ID: <87r0hhk60e.ffs@tglx>
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On Fri, Feb 02 2024 at 06:45, Rui Zhang wrote:
>> @@ -147,6 +148,9 @@ static void topo_set_ids(struct topo_sca
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0c->topo.pkg_id =3D topo_=
shift_apicid(apicid, TOPO_PKG_DOMAIN);
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0c->topo.die_id =3D topo_=
shift_apicid(apicid, TOPO_DIE_DOMAIN);
>> =C2=A0
>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0c->topo.logical_pkg_id =3D to=
pology_get_logical_id(apicid,
>> TOPO_PKG_DOMAIN);
>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0c->topo.logical_die_id =3D to=
pology_get_logical_id(apicid,
>> TOPO_DIE_DOMAIN);
>> +
>
> Just wondering if we could have logical_core_id.
>
> drivers/hwmon/coretemp.c uses an array to save per core temperature
> information. We cannot use core_id as array index because it can be
> sparse. Currently, to get the temperature info for a specified core,
> we need to traverse the array to know which core each entry maps to.
>
> Ideally, we could have a global logical_core_id, and use that as the
> array index directly.
> This can also simplify kernel code in many places when checking if two
> cpus are in the same core or not.

That's trivial to do now :)

It's an orthogonal change and we can put it on top once this pile is
merged.

Thanks,

        tglx