linux-kernel - Re: [tip:perf/urgent] x86, perf events: Check if we have APIC enabled

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Date:	Fri, 11 Dec 2009 09:39:32 +0100
From:	Christian Hartmann <cornogle@...glemail.com>
To:	linux-kernel@...r.kernel.org, Ralf.Hildebrandt@...rite.de
Subject: Re: [tip:perf/urgent] x86, perf events: Check if we have APIC enabled

Hello list,

wow, I reported this bug also "PROBLEM: WARNING: at
arch/x86/kernel/apic/apic.c:249 native_apic_write_dummy+0x32/0x3e()
(git 2.6.32-rc5)" on 22.october 09, this a delay of 1,5 month ;)
But anyway, good to know, that they comes now a hint from the kernel
by this patch... :)





2009/12/10 tip-bot for Cyrill Gorcunov <gorcunov@...nvz.org>:
> Commit-ID:  125580380f418000b1a06d9a54700f1191b6e561
> Gitweb:     http://git.kernel.org/tip/125580380f418000b1a06d9a54700f1191b6e561
> Author:     Cyrill Gorcunov <gorcunov@...nvz.org>
> AuthorDate: Thu, 10 Dec 2009 19:56:34 +0300
> Committer:  Ingo Molnar <mingo@...e.hu>
> CommitDate: Thu, 10 Dec 2009 18:00:30 +0100
>
> x86, perf events: Check if we have APIC enabled
>
> Ralf Hildebrandt reported this boot warning:
>
> | Running a vanilla 2.6.32 as Xen DomU, I'm getting:
> |
> | [    0.000999] CPU: Physical Processor ID: 0
> | [    0.000999] CPU: Processor Core ID: 1
> | [    0.000999] Performance Events: AMD PMU driver.
> | [    0.000999] ------------[ cut here ]------------
> | [    0.000999] WARNING: at arch/x86/kernel/apic/apic.c:249 native_apic_write_dummy
>
> So we need to check if APIC functionality is available, and
> not just in the P6 driver but elsewhere as well.
>
> Reported-by: Ralf Hildebrandt <Ralf.Hildebrandt@...rite.de>
> Signed-off-by: Cyrill Gorcunov <gorcunov@...nvz.org>
> Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> Cc: Mike Galbraith <efault@....de>
> Cc: Paul Mackerras <paulus@...ba.org>
> Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
> Cc: Frederic Weisbecker <fweisbec@...il.com>
> LKML-Reference: <20091210165634.GF5086@...ovo>
> Signed-off-by: Ingo Molnar <mingo@...e.hu>
> ---
>  arch/x86/kernel/cpu/perf_event.c |   18 ++++++++++++------
>  1 files changed, 12 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
> index 1342f23..18f05ec 100644
> --- a/arch/x86/kernel/cpu/perf_event.c
> +++ b/arch/x86/kernel/cpu/perf_event.c
> @@ -2066,12 +2066,6 @@ static __init int p6_pmu_init(void)
>
>        x86_pmu = p6_pmu;
>
> -       if (!cpu_has_apic) {
> -               pr_info("no APIC, boot with the \"lapic\" boot parameter to force-enable it.\n");
> -               pr_info("no hardware sampling interrupt available.\n");
> -               x86_pmu.apic = 0;
> -       }
> -
>        return 0;
>  }
>
> @@ -2163,6 +2157,16 @@ static __init int amd_pmu_init(void)
>        return 0;
>  }
>
> +static void __init pmu_check_apic(void)
> +{
> +       if (cpu_has_apic)
> +               return;
> +
> +       x86_pmu.apic = 0;
> +       pr_info("no APIC, boot with the \"lapic\" boot parameter to force-enable it.\n");
> +       pr_info("no hardware sampling interrupt available.\n");
> +}
> +
>  void __init init_hw_perf_events(void)
>  {
>        int err;
> @@ -2184,6 +2188,8 @@ void __init init_hw_perf_events(void)
>                return;
>        }
>
> +       pmu_check_apic();
> +
>        pr_cont("%s PMU driver.\n", x86_pmu.name);
>
>        if (x86_pmu.num_events > X86_PMC_MAX_GENERIC) {
> --
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