linux-kernel - [PATCH 02/11] perf hists: Trim libtraceevent trace

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Message-Id: <1470758494-32127-3-git-send-email-acme@kernel.org>
Date:	Tue,  9 Aug 2016 13:01:25 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	linux-kernel@...r.kernel.org,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	David Ahern <dsahern@...il.com>, Jiri Olsa <jolsa@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>
Subject: [PATCH 02/11] perf hists: Trim libtraceevent trace_seq buffers

From: Arnaldo Carvalho de Melo <acme@...hat.com>

When we use libtraceevent to format trace event fields into printable
strings to use in hist entries it is important to trim it from the
default 4 KiB it starts with to what is really used, to reduce the
memory footprint, so use realloc(seq.buffer, seq.len + 1) when returning
the seq.buffer formatted with the fields contents.

Reported-and-Tested-by: Wang Nan <wangnan0@...wei.com>
Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: David Ahern <dsahern@...il.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Namhyung Kim <namhyung@...nel.org>
Link: http://lkml.kernel.org/n/tip-t3hl7uxmilrkigzmc90rlhk2@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/util/sort.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/sort.c b/tools/perf/util/sort.c
index 947d21f38398..3d3cb8392c86 100644
--- a/tools/perf/util/sort.c
+++ b/tools/perf/util/sort.c
@@ -588,7 +588,11 @@ static char *get_trace_output(struct hist_entry *he)
 	} else {
 		pevent_event_info(&seq, evsel->tp_format, &rec);
 	}
-	return seq.buffer;
+	/*
+	 * Trim the buffer, it starts at 4KB and we're not going to
+	 * add anything more to this buffer.
+	 */
+	return realloc(seq.buffer, seq.len + 1);
 }
 
 static int64_t
-- 
2.7.4