linux-kernel - Re: [RFC] perf_sample

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Date:   Mon, 12 Aug 2019 12:09:35 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
Cc:     Jiri Olsa <jolsa@...hat.com>, Ingo Molnar <mingo@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Michael Petlan <mpetlan@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC] perf_sample_id::idx

On 9/08/19 7:04 PM, Arnaldo Carvalho de Melo wrote:
> Em Fri, Aug 09, 2019 at 03:20:14PM +0000, Hunter, Adrian escreveu:
> 
>> It will be used for AUX area sampling.  A sample will have AUX area
>> data that will be queued for decoding, where there are separate queues
>> for each CPU (per-cpu tracing) or task (per-thread tracing).  The
>> sample ID can be used to lookup 'idx' which is effectively the queue
>> number.
> 
> Would be good to have this as a comment in the perf_sample_id struct
> definition :-)


>From 45d57bd7b25c9864f21e25534274ea461ff83d9d Mon Sep 17 00:00:00 2001
From: Adrian Hunter <adrian.hunter@...el.com>
Date: Mon, 12 Aug 2019 12:06:31 +0300
Subject: [PATCH] perf tools: Add comment for idx in struct perf_sample_id

'idx' was added as preparation for AUX area sampling. Add a comment to
describe why.

Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
---
 tools/perf/util/evsel.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index cad54e8ba522..ba13eb771775 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -22,6 +22,13 @@ struct perf_sample_id {
 	struct hlist_node 	node;
 	u64		 	id;
 	struct perf_evsel	*evsel;
+	/*
+	 * 'idx' will be used for AUX area sampling. A sample will have AUX area
+	 * data that will be queued for decoding, where there are separate
+	 * queues for each CPU (per-cpu tracing) or task (per-thread tracing).
+	 * The sample ID can be used to lookup 'idx' which is effectively the
+	 * queue number.
+	 */
 	int			idx;
 	int			cpu;
 	pid_t			tid;
-- 
2.17.1