linux-kernel - Re: [PATCH -v3] perf, x86: try to handle unknown nmis with running perfctrs

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Date:	Thu, 19 Aug 2010 21:43:31 +0400
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Don Zickus <dzickus@...hat.com>,
	Robert Richter <robert.richter@....com>,
	Lin Ming <ming.m.lin@...el.com>, Ingo Molnar <mingo@...e.hu>,
	"fweisbec@...il.com" <fweisbec@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Huang, Ying" <ying.huang@...el.com>,
	Yinghai Lu <yinghai@...nel.org>,
	Andi Kleen <andi@...stfloor.org>
Subject: Re: [PATCH -v3] perf, x86: try to handle unknown nmis with running
	perfctrs

On Thu, Aug 19, 2010 at 04:27:13PM +0200, Peter Zijlstra wrote:
...
> Index: linux-2.6/arch/x86/kernel/cpu/perf_event_p4.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/cpu/perf_event_p4.c
> +++ linux-2.6/arch/x86/kernel/cpu/perf_event_p4.c
> @@ -673,7 +673,7 @@ static int p4_pmu_handle_irq(struct pt_r
>  		if (!overflow && (val & (1ULL << (x86_pmu.cntval_bits - 1))))
>  			continue;
>  
> -		handled += overflow;
> +		handled += !!overflow;

No need to !! here, overflowed returns [0;1] though a small nit
and could be updated later :)

>  
>  		/* event overflow for sure */
>  		data.period = event->hw.last_period;
> @@ -690,7 +690,7 @@ static int p4_pmu_handle_irq(struct pt_r
>  		inc_irq_stat(apic_perf_irqs);
>  	}
>  
> -	return handled > 0;
> +	return handled;
>  }
>  
>  /*
> 
	-- Cyrill
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