tracing: Format non-nanosec times from tsc clock without a decimal point.
With the addition of the "tsc" clock, formatting timestamps to look like
fractional seconds is misleading. Mark clocks as either in nanoseconds or
not, and format non-nanosecond timestamps as decimal integers.
Tested:
$ cd /sys/kernel/debug/tracing/
$ cat trace_clock
[local] global tsc
$ echo sched_switch > set_event
$ echo 1 > tracing_on ; sleep 0.0005 ; echo 0 > tracing_on
$ cat trace
<idle>-0 [000] 6330.555552: sched_switch: prev_comm=swapper prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=bash next_pid=29964 next_prio=120
sleep-29964 [000] 6330.555628: sched_switch: prev_comm=bash prev_pid=29964 prev_prio=120 prev_state=S ==> next_comm=swapper next_pid=0 next_prio=120
...
$ echo 1 > options/latency-format
$ cat trace
<idle>-0 0 4104553247us+: sched_switch: prev_comm=swapper prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=bash next_pid=29964 next_prio=120
sleep-29964 0 4104553322us+: sched_switch: prev_comm=bash prev_pid=29964 prev_prio=120 prev_state=S ==> next_comm=swapper next_pid=0 next_prio=120
...
$ echo tsc > trace_clock
$ cat trace
$ echo 1 > tracing_on ; sleep 0.0005 ; echo 0 > tracing_on
$ echo 0 > options/latency-format
$ cat trace
<idle>-0 [000] 16490053398357: sched_switch: prev_comm=swapper prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=bash next_pid=31128 next_prio=120
sleep-31128 [000] 16490053588518: sched_switch: prev_comm=bash prev_pid=31128 prev_prio=120 prev_state=S ==> next_comm=swapper next_pid=0 next_prio=120
...
echo 1 > options/latency-format
$ cat trace
<idle>-0 0 91557653238+: sched_switch: prev_comm=swapper prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=bash next_pid=31128 next_prio=120
sleep-31128 0 91557843399+: sched_switch: prev_comm=bash prev_pid=31128 prev_prio=120 prev_state=S ==> next_comm=swapper next_pid=0 next_prio=120
...
v2:
Move arch-specific bits out of generic code.
v4:
Fix x86_32 build due to 64-bit division.
Google-Bug-Id: 6980623
Link: http://lkml.kernel.org/r/1352837903-32191-2-git-send-email-dhsharp@google.com
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: David Sharp <dhsharp@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 0d20620..d943e69 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -484,10 +484,11 @@
static struct {
u64 (*func)(void);
const char *name;
+ int in_ns; /* is this clock in nanoseconds? */
} trace_clocks[] = {
- { trace_clock_local, "local" },
- { trace_clock_global, "global" },
- { trace_clock_counter, "counter" },
+ { trace_clock_local, "local", 1 },
+ { trace_clock_global, "global", 1 },
+ { trace_clock_counter, "counter", 0 },
ARCH_TRACE_CLOCKS
};
@@ -2478,6 +2479,10 @@
if (ring_buffer_overruns(iter->tr->buffer))
iter->iter_flags |= TRACE_FILE_ANNOTATE;
+ /* Output in nanoseconds only if we are using a clock in nanoseconds. */
+ if (trace_clocks[trace_clock_id].in_ns)
+ iter->iter_flags |= TRACE_FILE_TIME_IN_NS;
+
/* stop the trace while dumping */
tracing_stop();
@@ -3339,6 +3344,10 @@
if (trace_flags & TRACE_ITER_LATENCY_FMT)
iter->iter_flags |= TRACE_FILE_LAT_FMT;
+ /* Output in nanoseconds only if we are using a clock in nanoseconds. */
+ if (trace_clocks[trace_clock_id].in_ns)
+ iter->iter_flags |= TRACE_FILE_TIME_IN_NS;
+
iter->cpu_file = cpu_file;
iter->tr = &global_trace;
mutex_init(&iter->mutex);