From: Steven Rostedt <[email protected]>
When CONFIG_HIST_TRIGGERS_DEBUG is enabled, each trace event has a
"hist_debug" file that explains the histogram internal data. This is very
useful for debugging histograms.
One bit of data that was missing from this file was what function a
histogram field uses to process its data. The hist_field structure now has
a fn_num that is used by a switch statement in hist_fn_call() to call a
function directly (to avoid spectre mitigations).
Instead of displaying that number, create a string array that maps to the
histogram function enums so that the function for a field may be
displayed:
~# cat /sys/kernel/tracing/events/sched/sched_switch/hist_debug
[..]
hist_data: 0000000043d62762
n_vals: 2
n_keys: 1
n_fields: 3
val fields:
hist_data->fields[0]:
flags:
VAL: HIST_FIELD_FL_HITCOUNT
type: u64
size: 8
is_signed: 0
function: hist_field_counter()
hist_data->fields[1]:
flags:
HIST_FIELD_FL_VAR
var.name: __arg_3921_2
var.idx (into tracing_map_elt.vars[]): 0
type: unsigned long[]
size: 128
is_signed: 0
function: hist_field_nop()
key fields:
hist_data->fields[2]:
flags:
HIST_FIELD_FL_KEY
ftrace_event_field name: prev_pid
type: pid_t
size: 8
is_signed: 1
function: hist_field_s32()
The "function:" field above is added.
Signed-off-by: Steven Rostedt (Google) <[email protected]>
---
kernel/trace/trace_events_hist.c | 75 +++++++++++++++++++-------------
1 file changed, 44 insertions(+), 31 deletions(-)
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 4a7f945e368d..24441b30a1a4 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -105,38 +105,44 @@ enum field_op_id {
FIELD_OP_MULT,
};
+#define FIELD_FUNCS \
+ C(NOP, "nop"), \
+ C(VAR_REF, "var_ref"), \
+ C(COUNTER, "counter"), \
+ C(CONST, "const"), \
+ C(LOG2, "log2"), \
+ C(BUCKET, "bucket"), \
+ C(TIMESTAMP, "timestamp"), \
+ C(CPU, "cpu"), \
+ C(COMM, "comm"), \
+ C(STRING, "string"), \
+ C(DYNSTRING, "dynstring"), \
+ C(RELDYNSTRING, "reldynstring"), \
+ C(PSTRING, "pstring"), \
+ C(S64, "s64"), \
+ C(U64, "u64"), \
+ C(S32, "s32"), \
+ C(U32, "u32"), \
+ C(S16, "s16"), \
+ C(U16, "u16"), \
+ C(S8, "s8"), \
+ C(U8, "u8"), \
+ C(UMINUS, "uminus"), \
+ C(MINUS, "minus"), \
+ C(PLUS, "plus"), \
+ C(DIV, "div"), \
+ C(MULT, "mult"), \
+ C(DIV_POWER2, "div_power2"), \
+ C(DIV_NOT_POWER2, "div_not_power2"), \
+ C(DIV_MULT_SHIFT, "div_mult_shift"), \
+ C(EXECNAME, "execname"), \
+ C(STACK, "stack"),
+
+#undef C
+#define C(a, b) HIST_FIELD_FN_##a
+
enum hist_field_fn {
- HIST_FIELD_FN_NOP,
- HIST_FIELD_FN_VAR_REF,
- HIST_FIELD_FN_COUNTER,
- HIST_FIELD_FN_CONST,
- HIST_FIELD_FN_LOG2,
- HIST_FIELD_FN_BUCKET,
- HIST_FIELD_FN_TIMESTAMP,
- HIST_FIELD_FN_CPU,
- HIST_FIELD_FN_COMM,
- HIST_FIELD_FN_STRING,
- HIST_FIELD_FN_DYNSTRING,
- HIST_FIELD_FN_RELDYNSTRING,
- HIST_FIELD_FN_PSTRING,
- HIST_FIELD_FN_S64,
- HIST_FIELD_FN_U64,
- HIST_FIELD_FN_S32,
- HIST_FIELD_FN_U32,
- HIST_FIELD_FN_S16,
- HIST_FIELD_FN_U16,
- HIST_FIELD_FN_S8,
- HIST_FIELD_FN_U8,
- HIST_FIELD_FN_UMINUS,
- HIST_FIELD_FN_MINUS,
- HIST_FIELD_FN_PLUS,
- HIST_FIELD_FN_DIV,
- HIST_FIELD_FN_MULT,
- HIST_FIELD_FN_DIV_POWER2,
- HIST_FIELD_FN_DIV_NOT_POWER2,
- HIST_FIELD_FN_DIV_MULT_SHIFT,
- HIST_FIELD_FN_EXECNAME,
- HIST_FIELD_FN_STACK,
+ FIELD_FUNCS
};
/*
@@ -5845,6 +5851,12 @@ const struct file_operations event_hist_fops = {
};
#ifdef CONFIG_HIST_TRIGGERS_DEBUG
+
+#undef C
+#define C(a, b) b
+
+static const char * const field_funcs[] = { FIELD_FUNCS };
+
static void hist_field_debug_show_flags(struct seq_file *m,
unsigned long flags)
{
@@ -5909,6 +5921,7 @@ static int hist_field_debug_show(struct seq_file *m,
seq_printf(m, " type: %s\n", field->type);
seq_printf(m, " size: %u\n", field->size);
seq_printf(m, " is_signed: %u\n", field->is_signed);
+ seq_printf(m, " function: hist_field_%s()\n",
field_funcs[field->fn_num]);
return 0;
}
--
2.51.0
