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From: Nicholas Piggin <npiggin@gmail.com>
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>
Subject: Re: [PATCH v4 1/2] powerpc/time: Only set CONFIG_ARCH_HAS_SCALED_CPUTIME on PPC64
Date: Mon, 19 Aug 2019 23:56:43 +1000	[thread overview]
Message-ID: <1566222563.zuxi8x5ryi.astroid@bobo.none> (raw)
In-Reply-To: <26969bb5-c01b-0674-5773-027f1851bd44@c-s.fr>

Christophe Leroy's on August 14, 2019 4:31 pm:
> Hi Nick,
> 
> 
> Le 07/06/2018 à 03:43, Nicholas Piggin a écrit :
>> On Wed,  6 Jun 2018 14:21:08 +0000 (UTC)
>> Christophe Leroy <christophe.leroy@c-s.fr> wrote:
>> 
>>> scaled cputime is only meaningfull when the processor has
>>> SPURR and/or PURR, which means only on PPC64.
>>>
> 
> [...]
> 
>> 
>> I wonder if we could make this depend on PPC_PSERIES or even
>> PPC_SPLPAR as well? (That would be for a later patch)
> 
> Can we go further on this ?
> 
> Do we know exactly which configuration support scaled cputime, in 
> extenso have SPRN_SPURR and/or SPRN_PURR ?
> 
> 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

  reply	other threads:[~2019-08-19 13:56 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-06 14:21 Christophe Leroy
2018-06-06 14:21 ` [PATCH v4 2/2] powerpc/time: no steal_time when CONFIG_PPC_SPLPAR is not selected Christophe Leroy
2018-06-07  1:43 ` [PATCH v4 1/2] powerpc/time: Only set CONFIG_ARCH_HAS_SCALED_CPUTIME on PPC64 Nicholas Piggin
2019-08-14  6:31   ` Christophe Leroy
2019-08-19 13:56     ` Nicholas Piggin [this message]
2019-08-20 12:42     ` Michael Ellerman

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