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From: Andy Lutomirski <luto@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: nathanl@linux.ibm.com, Arnd Bergmann <arnd@arndb.de>,
	X86 ML <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>,
	"open list:MIPS" <linux-mips@vger.kernel.org>,
	Paul Mackerras <paulus@samba.org>,
	Andrew Lutomirski <luto@kernel.org>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [RFC PATCH v4 08/11] lib: vdso: allow fixed clock mode
Date: Thu, 16 Jan 2020 12:19:50 -0800
Message-ID: <CALCETrX9+PZ1h6xex2WZcSqNT7W-6R-E95jv9hLhSdAzhMCrTA@mail.gmail.com> (raw)
In-Reply-To: <874kwvf9by.fsf@nanos.tec.linutronix.de>

On Thu, Jan 16, 2020 at 12:14 PM Thomas Gleixner <tglx@linutronix.de> wrote:
>
> Christophe Leroy <christophe.leroy@c-s.fr> writes:
>
> Can you please adjust the prefix for future patches to lib/vdso: and
> start the sentence after the colon with an uppercase letter?
>
> > On arches like POWERPC, the clock is always the timebase, it
>
> Please spell out architectures. Changelogs are not space constraint.
>
> > cannot be changed on the fly and it is always VDSO capable.
>
> Also this sentence does not make sense as it might suggests that
> architectures with a fixed compile time known clocksource have something
> named timebase. Something like this is more clear:
>
> Some architectures have a fixed clocksource which is known at compile
> time and cannot be replaced or disabled at runtime, e.g. timebase on
> PowerPC. For such cases the clock mode check in the VDSO code is
> pointless.
>

I wonder if we should use this on x86 bare-metal if we have
sufficiently invariant TSC.  (Via static_cpu_has(), not compiled in.)
Maybe there is no such x86 machine.

I really really want Intel or AMD to introduce machines where the TSC
pinky-swears to count in actual nanoseconds.

--Andy

  reply index

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-16 17:58 [RFC PATCH v4 00/11] powerpc: switch VDSO to C implementation Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 01/11] powerpc/64: Don't provide time functions in compat VDSO32 Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 02/11] powerpc/vdso: Switch VDSO to generic C implementation Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 03/11] lib: vdso: only read hrtimer_res when needed in __cvdso_clock_getres() Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 04/11] powerpc/vdso: simplify __get_datapage() Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 05/11] lib: vdso: allow arches to provide vdso data pointer Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 06/11] powerpc/vdso: provide inline alternative to __get_datapage() Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 07/11] powerpc/vdso: provide vdso data pointer from the ASM caller Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 08/11] lib: vdso: allow fixed clock mode Christophe Leroy
2020-01-16 20:13   ` Thomas Gleixner
2020-01-16 20:19     ` Andy Lutomirski [this message]
2020-01-16 21:07       ` Thomas Gleixner
2020-01-16 17:58 ` [RFC PATCH v4 09/11] powerpc/vdso: override __arch_vdso_capable() Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 10/11] lib: vdso: Allow arches to override the ns shift operation Christophe Leroy
2020-01-16 19:47   ` Andy Lutomirski
2020-01-16 19:57     ` Thomas Gleixner
2020-01-16 20:20       ` Andy Lutomirski
2020-01-29  7:14         ` Thomas Gleixner
2020-01-29  7:26           ` Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 11/11] powerpc/32: provide vdso_shift_ns() Christophe Leroy
2020-01-17  8:58 ` [RFC PATCH v4 00/11] powerpc: switch VDSO to C implementation Segher Boessenkool
2020-01-17  9:26   ` Christophe Leroy
2020-01-20 14:56   ` Christophe Leroy
2020-01-20 15:19     ` Segher Boessenkool
2020-01-20 17:08       ` Christophe Leroy
2020-01-20 17:27         ` Segher Boessenkool

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