On Wed, 26 Jul 2023 20:16:18 +0800
Ze Gao <zegao2021@xxxxxxxxx> wrote:
> Since the sched_switch tracepoint introduces a new variable to
> report sched-out task state in symbolic char, we switch to use
> that instead to spare from knowing internal implementations
> in kernel.
This needs to be changed to check if the "prev_state_char" field exists,
and if not, then it must use the old method. Same for perf. The tools must
work with older kernels.
-- Steve
>
> Signed-off-by: Ze Gao <zegao@xxxxxxxxxxx>
> ---
> plugins/plugin_sched_switch.c | 29 ++++-------------------------
> 1 file changed, 4 insertions(+), 25 deletions(-)
>
> diff --git a/plugins/plugin_sched_switch.c b/plugins/plugin_sched_switch.c
> index 8752cae..5dbdc28 100644
> --- a/plugins/plugin_sched_switch.c
> +++ b/plugins/plugin_sched_switch.c
> @@ -9,27 +9,6 @@
> #include "event-parse.h"
> #include "trace-seq.h"
>
> -static void write_state(struct trace_seq *s, int val)
> -{
> - const char states[] = "SDTtZXxW";
> - int found = 0;
> - int i;
> -
> - for (i = 0; i < (sizeof(states) - 1); i++) {
> - if (!(val & (1 << i)))
> - continue;
> -
> - if (found)
> - trace_seq_putc(s, '|');
> -
> - found = 1;
> - trace_seq_putc(s, states[i]);
> - }
> -
> - if (!found)
> - trace_seq_putc(s, 'R');
> -}
> -
> static void write_and_save_comm(struct tep_format_field *field,
> struct tep_record *record,
> struct trace_seq *s, int pid)
> @@ -97,10 +76,10 @@ static int sched_switch_handler(struct trace_seq *s,
> trace_seq_printf(s, "%lld ", val);
>
> if (tep_get_field_val(s, event, "prev_prio", record, &val, 1) ==
> 0)
> - trace_seq_printf(s, "[%d] ", (int) val);
> + trace_seq_printf(s, "[%d] ", (short) val);
>
> - if (tep_get_field_val(s, event, "prev_state", record, &val, 1)
> == 0)
> - write_state(s, val);
> + if (tep_get_field_val(s, event, "prev_state_char", record,
> &val, 1) == 0)
> + trace_seq_putc(s, (char) val);
>
> trace_seq_puts(s, " ==> ");
>
> @@ -115,7 +94,7 @@ static int sched_switch_handler(struct trace_seq *s,
> trace_seq_printf(s, "%lld", val);
>
> if (tep_get_field_val(s, event, "next_prio", record, &val, 1) ==
> 0)
> - trace_seq_printf(s, " [%d]", (int) val);
> + trace_seq_printf(s, " [%d]", (short) val);
>
> return 0;
> }
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