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Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime()

From Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Newsgroups linux.kernel
Subject Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime()
Date 2015-10-28 20:30 +0100
Message-ID <qoEA2-6Ra-5@gated-at.bofh.it> (permalink)
References (8 earlier) <qow9s-1ly-11@gated-at.bofh.it> <qoDDY-6eY-21@gated-at.bofh.it> <qoDND-6j4-5@gated-at.bofh.it> <qoE70-6pV-25@gated-at.bofh.it> <qoEql-6NV-15@gated-at.bofh.it>
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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

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[PATCH v3 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() Markos Chandras <markos.chandras@imgtec.com> - 2015-10-21 11:00 +0200
  Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and  clock_gettime() Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> - 2015-10-23 03:50 +0200
    Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and  clock_gettime() Ralf Baechle <ralf@linux-mips.org> - 2015-10-27 15:50 +0100
      Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and  clock_gettime() Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> - 2015-10-27 21:50 +0100
        Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and  clock_gettime() David Daney <ddaney.cavm@gmail.com> - 2015-10-27 22:10 +0100
          Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and  clock_gettime() Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> - 2015-10-27 22:20 +0100
            Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and  clock_gettime() Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> - 2015-10-27 22:50 +0100
              Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() Alex Smith <alex@alex-smith.me.uk> - 2015-10-28 11:30 +0100
                Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and  clock_gettime() Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> - 2015-10-28 19:30 +0100
                Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() Alex Smith <alex@alex-smith.me.uk> - 2015-10-28 19:40 +0100
                Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and  clock_gettime() Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> - 2015-10-28 20:00 +0100
                Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() Alex Smith <alex@alex-smith.me.uk> - 2015-10-28 20:20 +0100
                Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and  clock_gettime() Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> - 2015-10-28 20:30 +0100
                Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() Alex Smith <alex@alex-smith.me.uk> - 2015-10-28 21:00 +0100
                Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and  clock_gettime() Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> - 2015-10-28 21:20 +0100
            Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and  clock_gettime() David Daney <ddaney.cavm@gmail.com> - 2015-10-27 22:50 +0100

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