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tracing: Reimplement log2 

log2 as currently implemented applies only to u64 trace_event_field
derived fields, and assumes that anything it's applied to is a u64
field.

To prepare for synthetic fields like latencies, log2 should be
applicable to those as well, so take the opportunity now to fix the
current problems as well as expand to more general uses.

log2 should be thought of as a chaining function rather than a field
type.  To enable this as well as possible future function
implementations, add a hist_field operand array into the hist_field
definition for this purpose, and make use of it to implement the log2
'function'.

Link: http://lkml.kernel.org/r/b47f93fc0b87b36eccf716b0c018f3a71e1f1111.1506105045.git.tom.zanussi@linux.intel.com

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Tom Zanussi 2017-09-22 14:58:23 -05:00 committed by Steven Rostedt (VMware)
parent 85013256cf
commit 5819eaddf3
1 changed files with 27 additions and 4 deletions
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31
kernel/trace/trace_events_hist.c
View File

@ -28,12 +28,16 @@ struct hist_field;
typedef u64 (*hist_field_fn_t) (struct hist_field *field, void *event);
#define HIST_FIELD_OPERANDS_MAX 2
struct hist_field {
struct ftrace_event_field *field;
unsigned long flags;
hist_field_fn_t fn;
unsigned int size;
unsigned int offset;
unsigned int is_signed;
struct hist_field *operands[HIST_FIELD_OPERANDS_MAX];
};
static u64 hist_field_none(struct hist_field *field, void *event)
@ -71,7 +75,9 @@ static u64 hist_field_pstring(struct hist_field *hist_field, void *event)
static u64 hist_field_log2(struct hist_field *hist_field, void *event)
{
u64 val = *(u64 *)(event + hist_field->field->offset);
struct hist_field *operand = hist_field->operands[0];
u64 val = operand->fn(operand, event);
return (u64) ilog2(roundup_pow_of_two(val));
}
@ -156,6 +162,8 @@ static const char *hist_field_name(struct hist_field *field,
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);
if (field_name == NULL)
field_name = "";
@ -357,8 +365,20 @@ static const struct tracing_map_ops hist_trigger_elt_comm_ops = {
.elt_init = hist_trigger_elt_comm_init,
};
static void destroy_hist_field(struct hist_field *hist_field)
static void destroy_hist_field(struct hist_field *hist_field,
unsigned int level)
{
unsigned int i;
if (level > 2)
return;
if (!hist_field)
return;
for (i = 0; i < HIST_FIELD_OPERANDS_MAX; i++)
destroy_hist_field(hist_field->operands[i], level + 1);
kfree(hist_field);
}
@ -385,7 +405,10 @@ static struct hist_field *create_hist_field(struct ftrace_event_field *field,
}
if (flags & HIST_FIELD_FL_LOG2) {
unsigned long fl = flags & ~HIST_FIELD_FL_LOG2;
hist_field->fn = hist_field_log2;
hist_field->operands[0] = create_hist_field(field, fl);
hist_field->size = hist_field->operands[0]->size;
goto out;
}
@ -405,7 +428,7 @@ static struct hist_field *create_hist_field(struct ftrace_event_field *field,
hist_field->fn = select_value_fn(field->size,
field->is_signed);
if (!hist_field->fn) {
destroy_hist_field(hist_field);
destroy_hist_field(hist_field, 0);
return NULL;
}
}
@ -422,7 +445,7 @@ static void destroy_hist_fields(struct hist_trigger_data *hist_data)
for (i = 0; i < TRACING_MAP_FIELDS_MAX; i++) {
if (hist_data->fields[i]) {
destroy_hist_field(hist_data->fields[i]);
destroy_hist_field(hist_data->fields[i], 0);
hist_data->fields[i] = NULL;
}
}