linux-kernel - Re: [PATCH] perf_events: fix BTS interrupt handling to avoid being dazed by NMI

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Message-ID: <AANLkTinghij+US6sbk4epU95HTQUt-SK_0UyM9iMHi7w@mail.gmail.com>
Date:	Fri, 10 Sep 2010 13:16:37 +0200
From:	Stephane Eranian <eranian@...gle.com>
To:	linux-kernel@...r.kernel.org
Cc:	peterz@...radead.org, mingo@...e.hu, paulus@...ba.org,
	davem@...emloft.net, fweisbec@...il.com,
	perfmon2-devel@...ts.sf.net, eranian@...il.com, eranian@...gle.com,
	robert.richter@....com, dzickus@...hat.com
Subject: Re: [PATCH] perf_events: fix BTS interrupt handling to avoid being
 dazed by NMI

Sorry, my patch is missing one piece. I will repost.


On Fri, Sep 10, 2010 at 1:09 PM, Stephane Eranian <eranian@...gle.com> wrote:
> Fix a bug introduced with commit de725de and the change in the meaning of the
> return value of intel_pmu_handle_irq(). With the current code, when you are
> using the BTS, you get 'dazed by NMI' each time the BTS buffer fills up.
>
> BTS does interrupt on the PMU vector, thus NMI. You need to take this
> into account in the return value of the function.
>
> Signed-off-by: Stephane Eranian <eranian@...gle.com>
> --
>
> diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
> index ee05c90..b4d2e1c 100644
> --- a/arch/x86/kernel/cpu/perf_event_intel.c
> +++ b/arch/x86/kernel/cpu/perf_event_intel.c
> @@ -713,18 +713,18 @@ static int intel_pmu_handle_irq(struct pt_regs *regs)
>        struct cpu_hw_events *cpuc;
>        int bit, loops;
>        u64 status;
> -       int handled = 0;
> +       int handled;
>
>        perf_sample_data_init(&data, 0);
>
>        cpuc = &__get_cpu_var(cpu_hw_events);
>
>        intel_pmu_disable_all();
> -       intel_pmu_drain_bts_buffer();
> +       handled = intel_pmu_drain_bts_buffer();
>        status = intel_pmu_get_status();
>        if (!status) {
>                intel_pmu_enable_all(0);
> -               return 0;
> +               return handled;
>        }
>
>        loops = 0;
>
--
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