linux-kernel - Re: [PATCH] perf record: Fix to honor user freq/interval properly

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Date:	Mon, 9 Jun 2014 12:22:31 +0200
From:	Jiri Olsa <jolsa@...hat.com>
To:	Namhyung Kim <namhyung@...nel.org>
Cc:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...nel.org>,
	Paul Mackerras <paulus@...ba.org>,
	Namhyung Kim <namhyung.kim@....com>,
	LKML <linux-kernel@...r.kernel.org>,
	Andi Kleen <andi@...stfloor.org>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: Re: [PATCH] perf record: Fix to honor user freq/interval properly

On Mon, Jun 09, 2014 at 02:43:37PM +0900, Namhyung Kim wrote:
> When configuring event perf checked a wrong condition that user
> specified both of freq (-F) and period (-c) or the event has no
> default value.  This worked because most of events don't have default
> value and only tracepoint events have default of 1 (and it's not
> desirable to change it for those events).
> 
> However, Andi's downloadable event patch changes the situation so it
> cannot change the value for those events.  Fix it by allowing override
> the default value if user gives one of the options.
> 
>   $ perf record -a -e uops_retired.all -F 4000 sleep 1
>   [ perf record: Woken up 1 times to write data ]
>   [ perf record: Captured and wrote 0.325 MB perf.data (~14185 samples) ]
> 
>   $ perf evlist -F
>   cpu/uops_retired.all/: sample_freq=4000
> 
> Cc: Andi Kleen <andi@...stfloor.org>
> Cc: Frederic Weisbecker <fweisbec@...il.com>
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> ---
>  tools/perf/util/evsel.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index 5c28d82b76c4..5ff811c67adc 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -589,10 +589,10 @@ void perf_evsel__config(struct perf_evsel *evsel, struct record_opts *opts)
>  	}
>  
>  	/*
> -	 * We default some events to a 1 default interval. But keep
> +	 * We default some events to have a default interval. But keep
>  	 * it a weak assumption overridable by the user.
>  	 */
> -	if (!attr->sample_period || (opts->user_freq != UINT_MAX &&
> +	if (!attr->sample_period || (opts->user_freq != UINT_MAX ||
>  				     opts->user_interval != ULLONG_MAX)) {

seems ok to me, maybe we could fixup brackets in that condition so
it does not seems like there's some hidden message ;-)

Acked-by: Jiri Olsa <jolsa@...hat.com>

thanks,
jirka
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