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Message-ID: <20230802110858.723d0fa1@gandalf.local.home>
Date: Wed, 2 Aug 2023 11:08:58 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Ze Gao <zegao2021@...il.com>
Cc: Adrian Hunter <adrian.hunter@...el.com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Ian Rogers <irogers@...gle.com>,
Ingo Molnar <mingo@...hat.com>, Jiri Olsa <jolsa@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Masami Hiramatsu <mhiramat@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
linux-trace-kernel@...r.kernel.org,
linux-trace-devel@...r.kernel.org, Ze Gao <zegao@...cent.com>
Subject: Re: [RFC PATCH v4 7/7] libtraceevent: prefer to use prev_state_char
introduced in sched_switch
On Wed, 2 Aug 2023 08:10:02 -0400
Ze Gao <zegao2021@...il.com> wrote:
> Since the sched_switch tracepoint introduces a new variable to
> report sched-out task state in symbolic char, we prefer to use
> it to spare from knowing internal implementations in kernel.
>
> Also we keep the old parsing logic intact but sync the state char
> array with the latest kernel.
>
This should also go to linux-trace-devel@...r.kernel.org.
> Signed-off-by: Ze Gao <zegao@...cent.com>
> ---
> plugins/plugin_sched_switch.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/plugins/plugin_sched_switch.c b/plugins/plugin_sched_switch.c
> index e0986ac..4c57322 100644
> --- a/plugins/plugin_sched_switch.c
> +++ b/plugins/plugin_sched_switch.c
> @@ -11,7 +11,7 @@
>
> static void write_state(struct trace_seq *s, int val)
> {
> - const char states[] = "SDTtXZPI";
> + const char states[] = "SDTtXZPIp";
> int found = 0;
> int i;
>
> @@ -99,7 +99,12 @@ static int sched_switch_handler(struct trace_seq *s,
> if (tep_get_field_val(s, event, "prev_prio", record, &val, 1) == 0)
> trace_seq_printf(s, "[%d] ", (int) val);
>
> - if (tep_get_field_val(s, event, "prev_state", record, &val, 1) == 0)
> + //find if has prev_state_char, otherwise fallback to prev_state
Use standard C comment notation "/* ... */"
> + if (tep_find_field(event, "prev_state_char")) {
> + if (tep_get_field_val(s, event, "prev_state_char", record, &val, 1) == 0)
> + trace_seq_putc(s, (char) val);
> + }
> + else if (tep_get_field_val(s, event, "prev_state", record, &val, 1) == 0)
This should be:
} else if (..) {
> write_state(s, val);
}
-- Steve
>
> trace_seq_puts(s, " ==> ");
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