@@ -167,16 +167,31 @@
The above sets up an initially paused hist trigger which is unpaused
and starts aggregating events when a given program is executed, and
which stops aggregating when the process exits and the hist trigger
is paused again.
The examples below provide a more concrete illustration of the
concepts and typical usage patterns discussed above.
+ 'special' event fields
+ ------------------------
+
+ There are a number of 'special event fields' available for use as
+ keys or values in a hist trigger. These look like and behave as if
+ they were actual event fields, but aren't really part of the event's
+ field definition or format file. They are however available for any
+ event, and can be used anywhere an actual event field could be.
+ They are:
+
+ common_timestamp u64 - timestamp (from ring buffer) associated
+ with the event, in nanoseconds. May be
+ modified by .usecs to have timestamps
+ interpreted as microseconds.
+ cpu int - the cpu on which the event occurred.
6.2 'hist' trigger examples
---------------------------
The first set of examples creates aggregations using the kmalloc
event. The fields that can be used for the hist trigger are listed
in the kmalloc event's format file:
@@ -222,16 +222,17 @@ enum hist_field_flags {
HIST_FIELD_FL_SYSCALL = 1 << 7,
HIST_FIELD_FL_STACKTRACE = 1 << 8,
HIST_FIELD_FL_LOG2 = 1 << 9,
HIST_FIELD_FL_TIMESTAMP = 1 << 10,
HIST_FIELD_FL_TIMESTAMP_USECS = 1 << 11,
HIST_FIELD_FL_VAR = 1 << 12,
HIST_FIELD_FL_EXPR = 1 << 13,
HIST_FIELD_FL_VAR_REF = 1 << 14,
+ HIST_FIELD_FL_CPU = 1 << 15,
};
struct var_defs {
unsigned int n_vars;
char *name[TRACING_MAP_VARS_MAX];
char *expr[TRACING_MAP_VARS_MAX];
};
@@ -1159,16 +1160,26 @@ static u64 hist_field_timestamp(struct hist_field *hist_field,
u64 ts = ring_buffer_event_time_stamp(rbe);
if (hist_data->attrs->ts_in_usecs && trace_clock_in_ns(tr))
ts = ns2usecs(ts);
return ts;
}
+static u64 hist_field_cpu(struct hist_field *hist_field,
+ struct tracing_map_elt *elt,
+ struct ring_buffer_event *rbe,
+ void *event)
+{
+ int cpu = smp_processor_id();
+
+ return cpu;
+}
+
static struct hist_field *
check_field_for_var_ref(struct hist_field *hist_field,
struct hist_trigger_data *var_data,
unsigned int var_idx)
{
struct hist_field *found = NULL;
if (hist_field && hist_field->flags & HIST_FIELD_FL_VAR_REF) {
@@ -1597,16 +1608,18 @@ static const char *hist_field_name(struct hist_field *field,
return field_name;
if (field->field)
field_name = field->field->name;
else if (field->flags & HIST_FIELD_FL_LOG2)
field_name = hist_field_name(field->operands[0], ++level);
else if (field->flags & HIST_FIELD_FL_TIMESTAMP)
field_name = "common_timestamp";
+ else if (field->flags & HIST_FIELD_FL_CPU)
+ field_name = "cpu";
else if (field->flags & HIST_FIELD_FL_EXPR ||
field->flags & HIST_FIELD_FL_VAR_REF) {
if (field->system) {
static char full_name[MAX_FILTER_STR_VAL];
strcat(full_name, field->system);
strcat(full_name, ".");
strcat(full_name, field->event_name);
@@ -2104,16 +2117,25 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
hist_field->fn = hist_field_timestamp;
hist_field->size = sizeof(u64);
hist_field->type = kstrdup("u64", GFP_KERNEL);
if (!hist_field->type)
goto free;
goto out;
}
+ if (flags & HIST_FIELD_FL_CPU) {
+ hist_field->fn = hist_field_cpu;
+ hist_field->size = sizeof(int);
+ hist_field->type = kstrdup("unsigned int", GFP_KERNEL);
+ if (!hist_field->type)
+ goto free;
+ goto out;
+ }
+
if (WARN_ON_ONCE(!field))
goto out;
if (is_string_field(field)) {
flags |= HIST_FIELD_FL_STRING;
hist_field->size = MAX_FILTER_STR_VAL;
hist_field->type = kstrdup(field->type, GFP_KERNEL);
@@ -2340,17 +2362,19 @@ parse_field(struct hist_trigger_data *hist_data, struct trace_event_file *file,
}
}
if (strcmp(field_name, "common_timestamp") == 0) {
*flags |= HIST_FIELD_FL_TIMESTAMP;
hist_data->enable_timestamps = true;
if (*flags & HIST_FIELD_FL_TIMESTAMP_USECS)
hist_data->attrs->ts_in_usecs = true;
- } else {
+ } else if (strcmp(field_name, "cpu") == 0)
+ *flags |= HIST_FIELD_FL_CPU;
+ else {
field = trace_find_event_field(file->event_call, field_name);
if (!field || !field->size) {
field = ERR_PTR(-EINVAL);
goto out;
}
}
out:
kfree(str);
@@ -4614,16 +4638,18 @@ static void hist_field_print(struct seq_file *m, struct hist_field *hist_field)
{
const char *field_name = hist_field_name(hist_field, 0);
if (hist_field->var.name)
seq_printf(m, "%s=", hist_field->var.name);
if (hist_field->flags & HIST_FIELD_FL_TIMESTAMP)
seq_puts(m, "common_timestamp");
+ else if (hist_field->flags & HIST_FIELD_FL_CPU)
+ seq_puts(m, "cpu");
else if (field_name) {
if (hist_field->flags & HIST_FIELD_FL_VAR_REF)
seq_putc(m, '$');
seq_printf(m, "%s", field_name);
}
if (hist_field->flags) {
const char *flags_str = get_hist_field_flags(hist_field);