linux-kernel - Re: [PATCH] perf: fix stat attach bogus counts

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Date:	Thu, 18 Mar 2010 18:36:15 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	linux-kernel@...r.kernel.org, peterz@...radead.org,
	paulus@...ba.org, davem@...emloft.net, fweisbec@...il.com,
	robert.richter@....com, perfmon2-devel@...ts.sf.net,
	eranian@...il.com
Subject: Re: [PATCH] perf: fix stat attach bogus counts


* Stephane Eranian <eranian@...gle.com> wrote:

> 	When perf stat -p pid is used, the events must be enabled
> 	immediately as there is no exec and thus no enable_on_exec.
> 
> 	Signed-off-by: Stephane Eranian <eranian@...gle.com>
> 
> --
>  builtin-stat.c |    6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index 95db31c..3a91fad 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -159,8 +159,10 @@ static void create_perf_stat_counter(int counter, int pid)
>  		}
>  	} else {
>  		attr->inherit	     = inherit;
> -		attr->disabled	     = 1;
> -		attr->enable_on_exec = 1;
> +		if (target_pid == -1) {
> +			attr->disabled	     = 1;
> +			attr->enable_on_exec = 1;
> +		}

Mind checking latest -tip, which has these commits:

d6d901c: perf events: Change perf parameter --pid to process-wide collection instead of thread-wid
46be604: perf record: Enable counters only when kernel is execing subcommand
6be2850: perf stat: Enable counters when collecting process-wide or system-wide data

as they fix/improve various --pid related behavioral aspects of perf. Does it 
work fine for you now?

	Ingo
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