tracing: Add support for recording tgid of tasks
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>
diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index 4c896a0..b341c02 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -12,27 +12,38 @@
#include "trace.h"
-static int sched_ref;
+#define RECORD_CMDLINE 1
+#define RECORD_TGID 2
+
+static int sched_cmdline_ref;
+static int sched_tgid_ref;
static DEFINE_MUTEX(sched_register_mutex);
static void
probe_sched_switch(void *ignore, bool preempt,
struct task_struct *prev, struct task_struct *next)
{
- if (unlikely(!sched_ref))
- return;
+ int flags;
- tracing_record_cmdline(prev);
- tracing_record_cmdline(next);
+ flags = (RECORD_TGID * !!sched_tgid_ref) +
+ (RECORD_CMDLINE * !!sched_cmdline_ref);
+
+ if (!flags)
+ return;
+ tracing_record_taskinfo_sched_switch(prev, next, flags);
}
static void
probe_sched_wakeup(void *ignore, struct task_struct *wakee)
{
- if (unlikely(!sched_ref))
- return;
+ int flags;
- tracing_record_cmdline(current);
+ flags = (RECORD_TGID * !!sched_tgid_ref) +
+ (RECORD_CMDLINE * !!sched_cmdline_ref);
+
+ if (!flags)
+ return;
+ tracing_record_taskinfo(current, flags);
}
static int tracing_sched_register(void)
@@ -75,28 +86,61 @@ static void tracing_sched_unregister(void)
unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
}
-static void tracing_start_sched_switch(void)
+static void tracing_start_sched_switch(int ops)
{
+ bool sched_register = (!sched_cmdline_ref && !sched_tgid_ref);
mutex_lock(&sched_register_mutex);
- if (!(sched_ref++))
+
+ switch (ops) {
+ case RECORD_CMDLINE:
+ sched_cmdline_ref++;
+ break;
+
+ case RECORD_TGID:
+ sched_tgid_ref++;
+ break;
+ }
+
+ if (sched_register && (sched_cmdline_ref || sched_tgid_ref))
tracing_sched_register();
mutex_unlock(&sched_register_mutex);
}
-static void tracing_stop_sched_switch(void)
+static void tracing_stop_sched_switch(int ops)
{
mutex_lock(&sched_register_mutex);
- if (!(--sched_ref))
+
+ switch (ops) {
+ case RECORD_CMDLINE:
+ sched_cmdline_ref--;
+ break;
+
+ case RECORD_TGID:
+ sched_tgid_ref--;
+ break;
+ }
+
+ if (!sched_cmdline_ref && !sched_tgid_ref)
tracing_sched_unregister();
mutex_unlock(&sched_register_mutex);
}
void tracing_start_cmdline_record(void)
{
- tracing_start_sched_switch();
+ tracing_start_sched_switch(RECORD_CMDLINE);
}
void tracing_stop_cmdline_record(void)
{
- tracing_stop_sched_switch();
+ tracing_stop_sched_switch(RECORD_CMDLINE);
+}
+
+void tracing_start_tgid_record(void)
+{
+ tracing_start_sched_switch(RECORD_TGID);
+}
+
+void tracing_stop_tgid_record(void)
+{
+ tracing_stop_sched_switch(RECORD_TGID);
}
