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From: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
To: Alex Smith <alex@alex-smith.me.uk>
Cc: David Daney <ddaney.cavm@gmail.com>,
	Ralf Baechle <ralf@linux-mips.org>,
	Markos Chandras <markos.chandras@imgtec.com>,
	linux-mips <linux-mips@linux-mips.org>,
	Alex Smith <alex.smith@imgtec.com>,
	<linux-kernel@vger.kernel.org>
Subject: Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime()
Date: Wed, 28 Oct 2015 12:28:21 -0700	[thread overview]
Message-ID: <563121D5.4030601@imgtec.com> (raw)
In-Reply-To: <CAOFt0_AvGQcxHAToEevTFt5JGiuhN03XnPxxjQizbZ3dC-06mg@mail.gmail.com>

On 10/28/2015 12:04 PM, Alex Smith wrote:
> On 28 October 2015 at 18:57, Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> wrote:
>>
> As I've explained the VDSO will only use the CP0 counter in the same
> situations that the kernel would when it is the active clocksource.
> Any issue that makes the counter unreliable affects the kernel as well
> and is unrelated to the VDSO, so a fix does not belong in this patch.

What would you do if some SoC with different type of cores will define 
CPU1 etc CP0_COUNT as a DIFFERENT clocksource from CPU0 (because of 
frequency etc)? Timekeeping can select CPU0 clocksource but code still 
uses a local CPU1 CP0_COUNT for gettimeofday().

And this kind of solution is the first in line to have an accurate 
timing in systems without GIC and with different clock frequencies.

- Leonid


  reply	other threads:[~2015-10-28 19:28 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-09-28 10:03 [PATCH 0/3] MIPS VDSO support Markos Chandras
2015-09-28 10:10 ` [PATCH 1/3] MIPS: Initial implementation of a VDSO Markos Chandras
2015-09-28 10:54   ` Alex Smith
2015-09-28 13:07     ` Matthew Fortune
2015-11-20 18:15       ` Maciej W. Rozycki
2015-09-28 10:11 ` [PATCH 2/3] irqchip: irq-mips-gic: Provide function to map GIC user section Markos Chandras
2015-09-28 10:55   ` Marc Zyngier
2015-09-28 14:16     ` Qais Yousef
2015-09-28 15:03       ` Marc Zyngier
2015-10-05  8:22     ` Markos Chandras
2015-10-12  9:40   ` [PATCH v2 " Markos Chandras
2015-10-12  9:51     ` Marc Zyngier
2015-10-12 10:16       ` Thomas Gleixner
2015-10-15  9:37         ` Qais Yousef
2015-10-15 10:18           ` Thomas Gleixner
2015-09-28 10:12 ` [PATCH 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() Markos Chandras
2015-09-28 13:15   ` kbuild test robot
2015-10-12 10:24   ` [PATCH v2 " Markos Chandras
2015-10-21  8:57     ` [PATCH v3 " Markos Chandras
2015-10-23  1:41       ` [v3, " Leonid Yegoshin
2015-10-27 14:47         ` Ralf Baechle
2015-10-27 20:46           ` Leonid Yegoshin
2015-10-27 21:02             ` David Daney
2015-10-27 21:15               ` Leonid Yegoshin
2015-10-27 21:44                 ` David Daney
2015-10-27 21:49                   ` Leonid Yegoshin
2015-10-28 10:20                     ` Alex Smith
2015-10-28 18:21                       ` Leonid Yegoshin
2015-10-28 18:30                         ` Alex Smith
2015-10-28 18:57                           ` Leonid Yegoshin
2015-10-28 19:04                             ` Alex Smith
2015-10-28 19:28                               ` Leonid Yegoshin [this message]
2015-10-28 19:55                                 ` Alex Smith
2015-10-28 20:15                                   ` Leonid Yegoshin
2016-01-25 22:36       ` [PATCH v3 " Hauke Mehrtens

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