linux-kernel - Re: [PATCH 8/8][RFC] perf: be paranoid about child times?

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Message-ID: <20091123105156.GA14736@elte.hu>
Date:	Mon, 23 Nov 2009 11:51:56 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	Paul Mackerras <paulus@...ba.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 8/8][RFC] perf: be paranoid about child times?


* Peter Zijlstra <a.p.zijlstra@...llo.nl> wrote:

> Normally we flatten the inherited hierarchy by attaching all childs to
> the top parent, therefore a child's child_total_time_* should never
> get incremented, add it anyway?
> 
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> ---
>  kernel/perf_event.c |    6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> Index: linux-2.6/kernel/perf_event.c
> ===================================================================
> --- linux-2.6.orig/kernel/perf_event.c
> +++ linux-2.6/kernel/perf_event.c
> @@ -1780,8 +1780,10 @@ u64 perf_event_read_value(struct perf_ev
>  
>  	list_for_each_entry(child, &event->child_list, child_list) {
>  		total += perf_event_read(child);
> -		*enabled += child->total_time_enabled;
> -		*running += child->total_time_running;
> +		*enabled += child->total_time_enabled +
> +			atomic64_read(&child->child_total_time_enabled);
> +		*running += child->total_time_running +
> +			atomic64_read(&child->child_total_time_running);

Stick in a WARN_ON_ONCE() instead?

	Ingo
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