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Date:   Mon, 19 Aug 2019 23:56:43 +1000
From:   Nicholas Piggin <npiggin@gmail.com>
Subject: Re: [PATCH v4 1/2] powerpc/time: Only set
 CONFIG_ARCH_HAS_SCALED_CPUTIME on PPC64
To:     Christophe Leroy <christophe.leroy@c-s.fr>
Cc:     Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        Michael Ellerman <mpe@ellerman.id.au>,
        Paul Mackerras <paulus@samba.org>,
        Segher Boessenkool <segher@kernel.crashing.org>
References: <d9ac8da98f53debb4758b98d0227979aca9196f7.1528292284.git.christophe.leroy@c-s.fr>
        <20180607114304.327c4ab5@roar.ozlabs.ibm.com>
        <26969bb5-c01b-0674-5773-027f1851bd44@c-s.fr>
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Christophe Leroy's on August 14, 2019 4:31 pm:
> Hi Nick,
>=20
>=20
> Le 07/06/2018 =C3=A0 03:43, Nicholas Piggin a =C3=A9crit=C2=A0:
>> On Wed,  6 Jun 2018 14:21:08 +0000 (UTC)
>> Christophe Leroy <christophe.leroy@c-s.fr> wrote:
>>=20
>>> scaled cputime is only meaningfull when the processor has
>>> SPURR and/or PURR, which means only on PPC64.
>>>
>=20
> [...]
>=20
>>=20
>> I wonder if we could make this depend on PPC_PSERIES or even
>> PPC_SPLPAR as well? (That would be for a later patch)
>=20
> Can we go further on this ?
>=20
> Do we know exactly which configuration support scaled cputime, in=20
> extenso have SPRN_SPURR and/or SPRN_PURR ?
>=20
> Ref https://github.com/linuxppc/issues/issues/171

Unfortunately I don't know enough about the timing stuff and who
uses it. SPURR is available on all configurations (guest, bare metal),
so it could account scaled time there too. I guess better just leave
it for now.

Thanks,
Nick
=