linux-kernel - Re: [PATCH 1/2] perf/x86/intel: Support adaptive PEBS for fixed counters

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Date:   Wed, 10 Apr 2019 09:41:39 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     kan.liang@...ux.intel.com
Cc:     mingo@...hat.com, linux-kernel@...r.kernel.org, tglx@...utronix.de,
        acme@...nel.org, jolsa@...nel.org, eranian@...gle.com,
        alexander.shishkin@...ux.intel.com, ak@...ux.intel.com
Subject: Re: [PATCH 1/2] perf/x86/intel: Support adaptive PEBS for fixed
 counters

On Tue, Apr 09, 2019 at 06:09:59PM -0700, kan.liang@...ux.intel.com wrote:
> From: Kan Liang <kan.liang@...ux.intel.com>
> 
> Fixed counters can also generate adaptive PEBS record, if the
> corresponding bit in IA32_FIXED_CTR_CTRL is set.
> Otherwise, only basic record is generated.
> 
> Unconditionally set the bit when PEBS is enabled on fixed counters.
> Let MSR_PEBS_CFG decide which format of PEBS record should be generated.
> There is no harmful to leave the bit set.

I'll merge this back into:

  Subject: perf/x86/intel: Support adaptive PEBSv4

such that this bug never existed, ok?

> 
> Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
> ---
>  arch/x86/events/intel/core.c      | 5 +++++
>  arch/x86/include/asm/perf_event.h | 1 +
>  2 files changed, 6 insertions(+)
> 
> diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
> index 56df0f6..f34d92b 100644
> --- a/arch/x86/events/intel/core.c
> +++ b/arch/x86/events/intel/core.c
> @@ -2174,6 +2174,11 @@ static void intel_pmu_enable_fixed(struct perf_event *event)
>  	bits <<= (idx * 4);
>  	mask = 0xfULL << (idx * 4);
>  
> +	if (x86_pmu.intel_cap.pebs_baseline && event->attr.precise_ip) {
> +		bits |= ICL_FIXED_0_ADAPTIVE << (idx * 4);
> +		mask |= ICL_FIXED_0_ADAPTIVE << (idx * 4);
> +	}
> +
>  	rdmsrl(hwc->config_base, ctrl_val);
>  	ctrl_val &= ~mask;
>  	ctrl_val |= bits;
> diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
> index dcb8bac..ce0dc88 100644
> --- a/arch/x86/include/asm/perf_event.h
> +++ b/arch/x86/include/asm/perf_event.h
> @@ -33,6 +33,7 @@
>  #define HSW_IN_TX					(1ULL << 32)
>  #define HSW_IN_TX_CHECKPOINTED				(1ULL << 33)
>  #define ICL_EVENTSEL_ADAPTIVE				(1ULL << 34)
> +#define ICL_FIXED_0_ADAPTIVE				(1ULL << 32)
>  
>  #define AMD64_EVENTSEL_INT_CORE_ENABLE			(1ULL << 36)
>  #define AMD64_EVENTSEL_GUESTONLY			(1ULL << 40)
> -- 
> 2.7.4
>