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tracing: Use a no_filter_buffering_ref to stop using the filter buffer 

Currently, the trace histograms relies on it using absolute time stamps to
trigger the tracing to not use the temp buffer if filters are set. That's
because the histograms need the full timestamp that is saved in the ring
buffer. That is no longer the case, as the ring_buffer_event_time_stamp()
can now return the time stamp for all events without all triggering a full
absolute time stamp.

Now that the absolute time stamp is an unrelated dependency to not using
the filters. There's nothing about having absolute timestamps to keep from
using the filter buffer. Instead, change the interface to explicitly state
to disable filter buffering that the histogram logic can use.

Link: https://lkml.kernel.org/r/20210316164113.847886563@goodmis.org

Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (VMware) 2021-03-16 12:41:05 -04:00
parent efe6196a6b
commit b94bc80df6
3 changed files with 17 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
kernel/trace/trace.c
View File

@ -2737,12 +2737,13 @@ trace_event_buffer_lock_reserve(struct trace_buffer **current_rb,
unsigned int trace_ctx)
{
struct ring_buffer_event *entry;
struct trace_array *tr = trace_file->tr;
int val;
*current_rb = trace_file->tr->array_buffer.buffer;
*current_rb = tr->array_buffer.buffer;
if (!ring_buffer_time_stamp_abs(*current_rb) && (trace_file->flags &
(EVENT_FILE_FL_SOFT_DISABLED | EVENT_FILE_FL_FILTERED)) &&
if (!tr->no_filter_buffering_ref &&
(trace_file->flags & (EVENT_FILE_FL_SOFT_DISABLED | EVENT_FILE_FL_FILTERED)) &&
(entry = this_cpu_read(trace_buffered_event))) {
/* Try to use the per cpu buffer first */
val = this_cpu_inc_return(trace_buffered_event_cnt);
@ -6971,31 +6972,26 @@ static int tracing_time_stamp_mode_open(struct inode *inode, struct file *file)
return ret;
}
int tracing_set_time_stamp_abs(struct trace_array *tr, bool abs)
/*
* Set or disable using the per CPU trace_buffer_event when possible.
*/
int tracing_set_filter_buffering(struct trace_array *tr, bool set)
{
int ret = 0;
mutex_lock(&trace_types_lock);
if (abs && tr->time_stamp_abs_ref++)
if (set && tr->no_filter_buffering_ref++)
goto out;
if (!abs) {
if (WARN_ON_ONCE(!tr->time_stamp_abs_ref)) {
if (!set) {
if (WARN_ON_ONCE(!tr->no_filter_buffering_ref)) {
ret = -EINVAL;
goto out;
}
if (--tr->time_stamp_abs_ref)
goto out;
--tr->no_filter_buffering_ref;
}
ring_buffer_set_time_stamp_abs(tr->array_buffer.buffer, abs);
#ifdef CONFIG_TRACER_MAX_TRACE
if (tr->max_buffer.buffer)
ring_buffer_set_time_stamp_abs(tr->max_buffer.buffer, abs);
#endif
out:
mutex_unlock(&trace_types_lock);

4
kernel/trace/trace.h
View File

@ -352,7 +352,7 @@ struct trace_array {
/* function tracing enabled */
int function_enabled;
#endif
int time_stamp_abs_ref;
int no_filter_buffering_ref;
struct list_head hist_vars;
#ifdef CONFIG_TRACER_SNAPSHOT
struct cond_snapshot *cond_snapshot;
@ -372,7 +372,7 @@ extern int tracing_check_open_get_tr(struct trace_array *tr);
extern struct trace_array *trace_array_find(const char *instance);
extern struct trace_array *trace_array_find_get(const char *instance);
extern int tracing_set_time_stamp_abs(struct trace_array *tr, bool abs);
extern int tracing_set_filter_buffering(struct trace_array *tr, bool set);
extern int tracing_set_clock(struct trace_array *tr, const char *clockstr);
extern bool trace_clock_in_ns(struct trace_array *tr);

6
kernel/trace/trace_events_hist.c
View File

@ -5484,7 +5484,7 @@ static int hist_register_trigger(char *glob, struct event_trigger_ops *ops,
goto out;
}
tracing_set_time_stamp_abs(file->tr, true);
tracing_set_filter_buffering(file->tr, true);
}
if (named_data)
@ -5592,7 +5592,7 @@ static void hist_unregister_trigger(char *glob, struct event_trigger_ops *ops,
if (hist_data->enable_timestamps) {
if (!hist_data->remove || unregistered)
tracing_set_time_stamp_abs(file->tr, false);
tracing_set_filter_buffering(file->tr, false);
}
}
@ -5639,7 +5639,7 @@ static void hist_unreg_all(struct trace_event_file *file)
update_cond_flag(file);
if (hist_data->enable_timestamps)
tracing_set_time_stamp_abs(file->tr, false);
tracing_set_filter_buffering(file->tr, false);
if (test->ops->free)
test->ops->free(test->ops, test);
}