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tracing: Add support for recording tgid of tasks

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Inorder to support recording of tgid, the following changes are made:

* Introduce a new API (tracing_record_taskinfo) to additionally record the tgid
  along with the task's comm at the same time. This has has the benefit of not
  setting trace_cmdline_save before all the information for a task is saved.
* Add a new API tracing_record_taskinfo_sched_switch to record task information
  for 2 tasks at a time (previous and next) and use it from sched_switch probe.
* Preserve the old API (tracing_record_cmdline) and create it as a wrapper
  around the new one so that existing callers aren't affected.
* Reuse the existing sched_switch and sched_wakeup probes to record tgid
  information and add a new option 'record-tgid' to enable recording of tgid

When record-tgid option isn't enabled to being with, we take care to make sure
that there's isn't memory or runtime overhead.

Link: http://lkml.kernel.org/r/20170627020155.5139-1-joelaf@google.com

Cc: kernel-team@android.com
Cc: Ingo Molnar <mingo@redhat.com>
Tested-by: Michael Sartain <mikesart@gmail.com>
Signed-off-by: Joel Fernandes <joelaf@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Joel Fernandes
2017-06-26 19:01:55 -07:00
committed by Steven Rostedt (VMware)
parent 83dd14933e
commit d914ba37d7
5 changed files with 213 additions and 26 deletions
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7
kernel/trace/trace.h
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@@ -640,6 +640,9 @@ void set_graph_array(struct trace_array *tr);
void tracing_start_cmdline_record(void);
void tracing_stop_cmdline_record(void);
void tracing_start_tgid_record(void);
void tracing_stop_tgid_record(void);
int register_tracer(struct tracer *type);
int is_tracing_stopped(void);
@@ -700,6 +703,7 @@ static inline void __trace_stack(struct trace_array *tr, unsigned long flags,
extern u64 ftrace_now(int cpu);
extern void trace_find_cmdline(int pid, char comm[]);
extern int trace_find_tgid(int pid);
extern void trace_event_follow_fork(struct trace_array *tr, bool enable);
#ifdef CONFIG_DYNAMIC_FTRACE
@@ -1124,6 +1128,7 @@ extern int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
C(CONTEXT_INFO, "context-info"), /* Print pid/cpu/time */ \
C(LATENCY_FMT, "latency-format"), \
C(RECORD_CMD, "record-cmd"), \
C(RECORD_TGID, "record-tgid"), \
C(OVERWRITE, "overwrite"), \
C(STOP_ON_FREE, "disable_on_free"), \
C(IRQ_INFO, "irq-info"), \
@@ -1440,6 +1445,8 @@ struct ftrace_event_field *
trace_find_event_field(struct trace_event_call *call, char *name);
extern void trace_event_enable_cmd_record(bool enable);
extern void trace_event_enable_tgid_record(bool enable);
extern int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr);
extern int event_trace_del_tracer(struct trace_array *tr);