[PATCH v4 5/5] tracing: Show hitcount value only when specified

Masami Hiramatsu (Google)
2022-08-27T04:04:09Z

From: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Show the hitcount value only when it is specified explicitly or
no value is specified.

# cd /sys/kernel/debug/tracing/
# echo hist:keys=pid:vals=runtime.percent,runtime.graph:sort=pid > \
events/sched/sched_stat_runtime/trigger
# sleep 10
# cat events/sched/sched_stat_runtime/hist
# event histogram
#
# trigger info: hist:keys=pid:vals=runtime.percent,runtime.graph:sort=pid:size=2048 [active]
#

{ pid: 14 } runtime (%): 0.97 runtime:
{ pid: 16 } runtime (%): 1.74 runtime:
{ pid: 26 } runtime (%): 0.13 runtime:
{ pid: 57 } runtime (%): 7.06 runtime: ###
{ pid: 61 } runtime (%): 11.06 runtime: #####
{ pid: 65 } runtime (%): 0.75 runtime:
{ pid: 70 } runtime (%): 0.98 runtime:
{ pid: 77 } runtime (%): 0.10 runtime:
{ pid: 125 } runtime (%): 0.56 runtime:
{ pid: 146 } runtime (%): 37.53 runtime: ####################
{ pid: 152 } runtime (%): 23.67 runtime: ############
{ pid: 153 } runtime (%): 15.39 runtime: ########

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
kernel/trace/trace_events_hist.c | 33 +++++++++++++++++++--------------
1 file changed, 19 insertions(+), 14 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index fceea784fded..35feeea84a38 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -508,6 +508,7 @@ enum hist_field_flags {
HIST_FIELD_FL_CONST = 1 << 18,
HIST_FIELD_FL_PERCENT = 1 << 19,
HIST_FIELD_FL_GRAPH = 1 << 20,
+ HIST_FIELD_FL_VAL = 1 << 21,
};

struct var_defs {
@@ -4204,7 +4205,8 @@ static int create_val_field(struct hist_trigger_data *hist_data,
if (WARN_ON(val_idx >= TRACING_MAP_VALS_MAX))
return -EINVAL;

- return __create_val_field(hist_data, val_idx, file, NULL, field_str, 0);
+ return __create_val_field(hist_data, val_idx, file, NULL, field_str,
+ HIST_FIELD_FL_VAL);
}

static const char no_comm[] = "(no comm)";
@@ -4355,8 +4357,11 @@ static int create_val_fields(struct hist_trigger_data *hist_data,
goto out;

fields_str = hist_data->attrs->vals_str;
- if (!fields_str)
+ if (!fields_str) {
+ /* If there is no value, use hitcount as a value */
+ hist_data->fields[HITCOUNT_IDX]->flags |= HIST_FIELD_FL_VAL;
goto out;
+ }

for (i = 0, j = 1; i < TRACING_MAP_VALS_MAX &&
j < TRACING_MAP_VALS_MAX; i++) {
@@ -4372,6 +4377,8 @@ static int create_val_fields(struct hist_trigger_data *hist_data,
if (strncmp(field_str + 8, ".graph", 8) == 0)
hist_data->fields[HITCOUNT_IDX]->flags |=
HIST_FIELD_FL_GRAPH;
+ hist_data->fields[HITCOUNT_IDX]->flags |=
+ HIST_FIELD_FL_VAL;
continue;
}

@@ -5392,13 +5399,13 @@ static void hist_trigger_entry_print(struct seq_file *m,
hist_trigger_print_key(m, hist_data, key, elt);

flags = hist_data->fields[i]->flags;
- hist_trigger_print_val(m, i, "hitcount", flags, stats, elt);
+ if (flags & HIST_FIELD_FL_VAL)
+ hist_trigger_print_val(m, i, "hitcount", flags, stats, elt);

for (i = 1; i < hist_data->n_vals; i++) {
field_name = hist_field_name(hist_data->fields[i], 0);
flags = hist_data->fields[i]->flags;
-
- if (flags & HIST_FIELD_FL_VAR || flags & HIST_FIELD_FL_EXPR)
+ if (!(flags & HIST_FIELD_FL_VAL))
continue;

seq_puts(m, " ");
@@ -5842,6 +5849,7 @@ static int event_hist_trigger_print(struct seq_file *m,
struct hist_trigger_data *hist_data = data->private_data;
struct hist_field *field;
bool have_var = false;
+ bool show_val = false;
unsigned int i;

seq_puts(m, HIST_PREFIX);
@@ -5872,16 +5880,13 @@ static int event_hist_trigger_print(struct seq_file *m,
continue;
}

- if (i == HITCOUNT_IDX) {
- seq_puts(m, "hitcount");
- if (field->flags & HIST_FIELD_FL_PERCENT)
- seq_puts(m, ".percent");
- else if (field->flags & HIST_FIELD_FL_GRAPH)
- seq_puts(m, ".graph");
- } else {
+ if (!(field->flags & HIST_FIELD_FL_VAL))
+ continue;
+
+ if (show_val)
seq_puts(m, ",");
- hist_field_print(m, field);
- }
+ hist_field_print(m, field);
+ show_val = true;
}

if (have_var) {