Re: [PATCH -v3] perf, x86: try to handle unknown nmis with runningperfctrs

[Robert Richter]

On 26.08.10 17:14:24, Don Zickus wrote:
> diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
> index 4539b4b..d16ebd8 100644
> --- a/arch/x86/kernel/cpu/perf_event_intel.c
> +++ b/arch/x86/kernel/cpu/perf_event_intel.c
> @@ -738,6 +738,7 @@ again:
>  
>  	inc_irq_stat(apic_perf_irqs);
>  	ack = status;
> +	intel_pmu_ack_status(ack);

Yes, not immediately ack'ing the status was suspect to me too. Though
it must then be the same counter that retriggers. Or, it is a cpu
bug. You could add a debug print of the status register for the case
the loop is reentered, would be interesting...

Thank for fixing this.

-Robert

>  
>  	intel_pmu_lbr_read();
>  
> @@ -766,8 +767,6 @@ again:
>  			x86_pmu_stop(event);
>  	}
>  
> -	intel_pmu_ack_status(ack);
> -
>  	/*
>  	 * Repeat if there is more work to be done:
>  	 */
> 

-- 
Advanced Micro Devices, Inc.
Operating System Research Center

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