linux-kernel - [PATCH perf/urgent] perf top: Always sample time

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Date:   Mon, 15 Apr 2019 14:53:33 +0200
From:   Jiri Olsa <jolsa@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Bastian Beischer <bastian.beischer@...h-aachen.de>
Subject: [PATCH perf/urgent] perf top: Always sample time

Bastian reported broken perf top -p PID command, it won't
display any data.

The problem is that for -p option we monitor single thread,
so we don't enable time in samples, because it's not needed.

However since commit 16c66bc167cc we use ordered queues to
stash data plus later commits added logic for dropping samples
in case there's big load and we don't keep up. All this needs
timestamp for sample. Enabling it unconditionally for perf top.

Fixes: 16c66bc167cc ("perf top: Add processing thread")
Reported-by: Bastian Beischer <bastian.beischer@...h-aachen.de>
Link: http://lkml.kernel.org/n/tip-zhn7jg8hqpl9547g7vqjini7@git.kernel.org
Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
 tools/perf/builtin-top.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 1999d6533d12..fbbb0da43abb 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1377,6 +1377,7 @@ int cmd_top(int argc, const char **argv)
 			 * */
 			.overwrite	= 0,
 			.sample_time	= true,
+			.sample_time_set = true,
 		},
 		.max_stack	     = sysctl__max_stack(),
 		.annotation_opts     = annotation__default_options,
-- 
2.17.2