Re: [patch V2 35/67] arm/perf: Convert to hotplug state machine

From	Mark Rutland <mark.rutland@arm.com>
Newsgroups	linux.kernel
Subject	Re: [patch V2 35/67] arm/perf: Convert to hotplug state machine
Date	2016-07-15 18:20 +0200
Message-ID	<rVe0h-D2-13@gated-at.bofh.it> (permalink)
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On Fri, Jul 15, 2016 at 05:26:30PM +0200, Sebastian Andrzej Siewior wrote:
> * Mark Rutland | 2016-07-15 14:08:18 [+0100]:
> 
> >Hi,
> Hi Mark,
> 
> >We may have multiple PMUs (e.g. two in big.LITTLE systems), and
> >__oprofile_cpu_pmu only contains one of these. So this conversion is not
> >correct.
> >
> >We were relying on the notifier list implicitly containing a list of
> >those PMUs. It seems like we need an explicit list here.
> >
> >We keep __oprofile_cpu_pmu around for legacy 32-bit users of OProfile
> >(on non-hetereogeneous systems), and that's all that the variable should
> >be used for.
> 
> By the time I'e been looking there was only one node in the .dts. Now
> you say it is not only possible but likely to have more than one node.

Yes. For example, arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts is a
big.LITTLE system with a Cortex-A7 PMU and a Cortex-A15 PMU.

> So what we need is a list which gets extended in cpu_pmu_init() instead
> of using the global pointer we have now. Correct?

Yes, that sounds right to me, with matching removal in cpu_pmu_destroy.

Thanks,
Mark.

Thread

[patch V2 35/67] arm/perf: Convert to hotplug state machine Anna-Maria Gleixner <anna-maria@linutronix.de> - 2016-07-13 19:30 +0200
  Re: [patch V2 35/67] arm/perf: Convert to hotplug state machine Mark Rutland <mark.rutland@arm.com> - 2016-07-15 15:10 +0200
    Re: [patch V2 35/67] arm/perf: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-07-15 17:30 +0200
      Re: [patch V2 35/67] arm/perf: Convert to hotplug state machine Mark Rutland <mark.rutland@arm.com> - 2016-07-15 18:20 +0200
  [tip:smp/hotplug] arm/perf: Convert to hotplug state machine tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2016-07-19 09:20 +0200
    Re: [tip:smp/hotplug] arm/perf: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-07-19 09:40 +0200
      Re: [tip:smp/hotplug] arm/perf: Convert to hotplug state machine Ingo Molnar <mingo@kernel.org> - 2016-07-19 09:50 +0200
        [PATCH v2] arm/perf: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-07-19 11:10 +0200
          Re: [PATCH v2] arm/perf: Convert to hotplug state machine Mark Rutland <mark.rutland@arm.com> - 2016-07-19 12:00 +0200
            [PATCH v3] arm/perf: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-07-19 13:20 +0200
              Re: [PATCH v3] arm/perf: Convert to hotplug state machine Ingo Molnar <mingo@kernel.org> - 2016-07-20 10:10 +0200
              [tip:smp/hotplug] arm/perf: Fix hotplug state machine conversion tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-07-20 12:50 +0200

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