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Date: Fri, 15 May 2009 15:35:47 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>,
       Corey Ashford <cjashfor@linux.vnet.ibm.com>,
       linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
       Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: Re: [PATCH 3/4] perf_counter: frequency based adaptive irq_period
Message-ID: <20090515133547.GA9285@elte.hu>
References: <20090515131925.616419905@chello.nl> <20090515132018.646195868@chello.nl>
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* Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:

> @@ -2907,6 +2940,12 @@ perf_counter_alloc(struct perf_counter_h
>  
>  	pmu = NULL;
>  
> +	hwc = &counter->hw;
> +	if (hw_event->freq && hw_event->irq_freq)
> +		hwc->irq_period = TICK_NSEC / hw_event->irq_freq;

this needs to use a 64-bit do_div method too, otherwise we get this 
on 32-bit:

 kernel/built-in.o: In function `perf_counter_alloc':
 perf_counter.c:(.text+0x7ddc7): undefined reference to `__udivdi3'

	Ingo