linux-kernel - Re: [PATCHv2] perf/stat: Report unsupported events properly

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Message-ID: <54E31458.3060009@arm.com>
Date:	Tue, 17 Feb 2015 10:13:44 +0000
From:	"Suzuki K. Poulose" <Suzuki.Poulose@....com>
To:	Arnaldo Carvalho de Melo <acme@...hat.com>,
	David Ahern <dsahern@...il.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Jiri Olsa <jolsa@...nel.org>
Subject: Re: [PATCHv2] perf/stat: Report unsupported events properly

On 13/02/15 20:50, Arnaldo Carvalho de Melo wrote:
> Em Fri, Feb 13, 2015 at 12:39:24PM -0700, David Ahern escreveu:
>>
>>
>> On 02/13/2015 11:40 AM, Suzuki K. Poulose wrote:
>>> From: "Suzuki K. Poulose" <suzuki.poulose@....com>
>>>
>>> Commit 1971f59 (perf stat: Use read_counter in read_counter_aggr )
>>> broke the perf stat output for unsupported counters.
>>>
>>>   $ perf stat -v -a -C 0 -e CCI_400/config=24/ sleep 1
>>>   Warning:
>>>   CCI_400/config=24/ event is not supported by the kernel.
>>>
>>>    Performance counter stats for 'system wide':
>>>
>>>                    0      CCI_400/config=24/
>>>
>>>          1.080265400 seconds time elapsed
>>>
>>> Where it used to be :
>>>
>>> $ perf stat -v -a -C 0 -e CCI_400/config=24/ sleep 1
>>>   Warning:
>>>   CCI_400/config=24/ event is not supported by the kernel.
>>>
>>>    Performance counter stats for 'system wide':
>>>
>>>      <not supported>      CCI_400/config=24/
>>>
>>>          1.083840675 seconds time elapsed
>>>
>>> This patch fixes the issues by checking if the counter is supported,
>>> before reading and logging the counter value.
>>>
>>> Cc: Jiri Olsa <jolsa@...nel.org>
>>> Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
>>> Signed-off-by: Suzuki K. Poulose <suzuki.poulose@....com>
>>> ---
>>>   tools/perf/builtin-stat.c |    5 ++++-
>>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
>>> index e598e4e..d28949d 100644
>>> --- a/tools/perf/builtin-stat.c
>>> +++ b/tools/perf/builtin-stat.c
>>> @@ -510,6 +510,9 @@ static int read_counter(struct perf_evsel *counter)
>>>   	int ncpus = perf_evsel__nr_cpus(counter);
>>>   	int cpu, thread;
>>>
>>> +	if (!counter->supported)
>>> +		return -ENOENT;
>>> +
>>>   	if (counter->system_wide)
>>>   		nthreads = 1;
>>>
>>> @@ -1285,7 +1288,7 @@ static void print_counter_aggr(struct perf_evsel *counter, char *prefix)
>>>   	if (prefix)
>>>   		fprintf(output, "%s", prefix);
>>>
>>> -	if (scaled == -1) {
>>> +	if (scaled == -1 || !counter->supported) {
>>>   		fprintf(output, "%*s%s",
>>>   			csv_output ? 0 : 18,
>>>   			counter->supported ? CNTR_NOT_COUNTED : CNTR_NOT_SUPPORTED,
>>>
>>
>> Just hit this as well.
>>
>> Acked-and-Tested-by: David Ahern <dsahern@...il.com>
>
> Gack, 10ms after I sent my pre-California pull req :-\
>
> Will go in the next one :-)
I think this may need to goto 3.19 stable series as well. Missed that. 
Do you want me to send it there ?

Cheers
Suzuki


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