Commit 067fe038 authored by Tom Zanussi's avatar Tom Zanussi Committed by Steven Rostedt (VMware)

tracing: Add variable reference handling to hist triggers

Add the necessary infrastructure to allow the variables defined on one
event to be referenced in another.  This allows variables set by a
previous event to be referenced and used in expressions combining the
variable values saved by that previous event and the event fields of
the current event.  For example, here's how a latency can be
calculated and saved into yet another variable named 'wakeup_lat':

    # echo 'hist:keys=pid,prio:ts0=common_timestamp ...
    # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp-$ts0 ...

In the first event, the event's timetamp is saved into the variable
ts0.  In the next line, ts0 is subtracted from the second event's
timestamp to produce the latency.

Further users of variable references will be described in subsequent
patches, such as for instance how the 'wakeup_lat' variable above can
be displayed in a latency histogram.

Link: http://lkml.kernel.org/r/b1d3e6975374e34d501ff417c20189c3f9b2c7b8.1516069914.git.tom.zanussi@linux.intel.comSigned-off-by: default avatarTom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 19a9facd
...@@ -7783,6 +7783,7 @@ static int instance_mkdir(const char *name) ...@@ -7783,6 +7783,7 @@ static int instance_mkdir(const char *name)
INIT_LIST_HEAD(&tr->systems); INIT_LIST_HEAD(&tr->systems);
INIT_LIST_HEAD(&tr->events); INIT_LIST_HEAD(&tr->events);
INIT_LIST_HEAD(&tr->hist_vars);
if (allocate_trace_buffers(tr, trace_buf_size) < 0) if (allocate_trace_buffers(tr, trace_buf_size) < 0)
goto out_free_tr; goto out_free_tr;
...@@ -8533,6 +8534,7 @@ __init static int tracer_alloc_buffers(void) ...@@ -8533,6 +8534,7 @@ __init static int tracer_alloc_buffers(void)
INIT_LIST_HEAD(&global_trace.systems); INIT_LIST_HEAD(&global_trace.systems);
INIT_LIST_HEAD(&global_trace.events); INIT_LIST_HEAD(&global_trace.events);
INIT_LIST_HEAD(&global_trace.hist_vars);
list_add(&global_trace.list, &ftrace_trace_arrays); list_add(&global_trace.list, &ftrace_trace_arrays);
apply_trace_boot_options(); apply_trace_boot_options();
......
...@@ -274,6 +274,7 @@ struct trace_array { ...@@ -274,6 +274,7 @@ struct trace_array {
int function_enabled; int function_enabled;
#endif #endif
int time_stamp_abs_ref; int time_stamp_abs_ref;
struct list_head hist_vars;
}; };
enum { enum {
...@@ -1548,6 +1549,8 @@ extern void pause_named_trigger(struct event_trigger_data *data); ...@@ -1548,6 +1549,8 @@ extern void pause_named_trigger(struct event_trigger_data *data);
extern void unpause_named_trigger(struct event_trigger_data *data); extern void unpause_named_trigger(struct event_trigger_data *data);
extern void set_named_trigger_data(struct event_trigger_data *data, extern void set_named_trigger_data(struct event_trigger_data *data,
struct event_trigger_data *named_data); struct event_trigger_data *named_data);
extern struct event_trigger_data *
get_named_trigger_data(struct event_trigger_data *data);
extern int register_event_command(struct event_command *cmd); extern int register_event_command(struct event_command *cmd);
extern int unregister_event_command(struct event_command *cmd); extern int unregister_event_command(struct event_command *cmd);
extern int register_trigger_hist_enable_disable_cmds(void); extern int register_trigger_hist_enable_disable_cmds(void);
......
This diff is collapsed.
...@@ -909,6 +909,12 @@ void set_named_trigger_data(struct event_trigger_data *data, ...@@ -909,6 +909,12 @@ void set_named_trigger_data(struct event_trigger_data *data,
data->named_data = named_data; data->named_data = named_data;
} }
struct event_trigger_data *
get_named_trigger_data(struct event_trigger_data *data)
{
return data->named_data;
}
static void static void
traceon_trigger(struct event_trigger_data *data, void *rec, traceon_trigger(struct event_trigger_data *data, void *rec,
struct ring_buffer_event *event) struct ring_buffer_event *event)
......
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