linux-kernel - Re: perf record: regression with latest PT fix

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Date:   Mon, 18 Dec 2017 16:25:27 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Stephane Eranian <eranian@...gle.com>
Cc:     Jiri Olsa <jolsa@...hat.com>, LKML <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>
Subject: Re: perf record: regression with latest PT fix

On 18/12/17 15:28, Alexander Shishkin wrote:
> On Mon, Dec 18, 2017 at 05:03:53AM -0800, Stephane Eranian wrote:
>> Hi,
>>
>>
>> The following patch:
>>
>> f785657b0fbe perf report: Fix regression when decoding Intel-PT traces
> 
> Cc'ing Adrian in case he missed the patch.

Doesn't seem to have much to do with Intel PT, but the patch logic looks wrong:

 		ret = perf_evlist__parse_sample_timestamp(evlist, event, &timestamp);
-		if (ret)
+		if (ret != -1)
 			return ret;

Shouldn't that be:

 		ret = perf_evlist__parse_sample_timestamp(evlist, event, &timestamp);
-		if (ret)
+		if (ret && ret != -1)
 			return ret;


> 
>> is breaking perf report for me. I get no samples reported from perf report
>> when running simple perf record commands:
>>
>> $ perf record -e cycles noploop
>>
>> Reverting the patch fixes the problem.
>>
>> Are you seeing this as well?
>