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>

3 files changed, 65 insertions, 32 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 0d20620c0d27..d943e69569cd 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -484,10 +484,11 @@ static const char *trace_options[] = {
 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 @@ __tracing_open(struct inode *inode, struct file *file)
         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 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
         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);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 55010ed175f0..c75d7988902c 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -406,10 +406,6 @@ void tracing_stop_sched_switch_record(void);
 void tracing_start_sched_switch_record(void);
 int register_tracer(struct tracer *type);
 int is_tracing_stopped(void);
-enum trace_file_type {
-        TRACE_FILE_LAT_FMT      = 1,
-        TRACE_FILE_ANNOTATE     = 2,
-};
 
 extern cpumask_var_t __read_mostly tracing_buffer_mask;
 
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index 123b189c732c..194d79602dc7 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -610,24 +610,54 @@ lat_print_generic(struct trace_seq *s, struct trace_entry *entry, int cpu)
         return trace_print_lat_fmt(s, entry);
 }
 
-static unsigned long preempt_mark_thresh = 100;
+static unsigned long preempt_mark_thresh_us = 100;
 
 static int
-lat_print_timestamp(struct trace_seq *s, u64 abs_usecs,
-                    unsigned long rel_usecs)
+lat_print_timestamp(struct trace_iterator *iter, u64 next_ts)
 {
-        return trace_seq_printf(s, " %4lldus%c: ", abs_usecs,
-                                rel_usecs > preempt_mark_thresh ? '!' :
-                                  rel_usecs > 1 ? '+' : ' ');
+        unsigned long verbose = trace_flags & TRACE_ITER_VERBOSE;
+        unsigned long in_ns = iter->iter_flags & TRACE_FILE_TIME_IN_NS;
+        unsigned long long abs_ts = iter->ts - iter->tr->time_start;
+        unsigned long long rel_ts = next_ts - iter->ts;
+        struct trace_seq *s = &iter->seq;
+
+        if (in_ns) {
+                abs_ts = ns2usecs(abs_ts);
+                rel_ts = ns2usecs(rel_ts);
+        }
+
+        if (verbose && in_ns) {
+                unsigned long abs_usec = do_div(abs_ts, USEC_PER_MSEC);
+                unsigned long abs_msec = (unsigned long)abs_ts;
+                unsigned long rel_usec = do_div(rel_ts, USEC_PER_MSEC);
+                unsigned long rel_msec = (unsigned long)rel_ts;
+
+                return trace_seq_printf(
+                                s, "[%08llx] %ld.%03ldms (+%ld.%03ldms): ",
+                                ns2usecs(iter->ts),
+                                abs_msec, abs_usec,
+                                rel_msec, rel_usec);
+        } else if (verbose && !in_ns) {
+                return trace_seq_printf(
+                                s, "[%016llx] %lld (+%lld): ",
+                                iter->ts, abs_ts, rel_ts);
+        } else if (!verbose && in_ns) {
+                return trace_seq_printf(
+                                s, " %4lldus%c: ",
+                                abs_ts,
+                                rel_ts > preempt_mark_thresh_us ? '!' :
+                                  rel_ts > 1 ? '+' : ' ');
+        } else { /* !verbose && !in_ns */
+                return trace_seq_printf(s, " %4lld: ", abs_ts);
+        }
 }
 
 int trace_print_context(struct trace_iterator *iter)
 {
         struct trace_seq *s = &iter->seq;
         struct trace_entry *entry = iter->ent;
-        unsigned long long t = ns2usecs(iter->ts);
-        unsigned long usec_rem = do_div(t, USEC_PER_SEC);
-        unsigned long secs = (unsigned long)t;
+        unsigned long long t;
+        unsigned long secs, usec_rem;
         char comm[TASK_COMM_LEN];
         int ret;
 
@@ -644,8 +674,13 @@ int trace_print_context(struct trace_iterator *iter)
                         return 0;
         }
 
-        return trace_seq_printf(s, " %5lu.%06lu: ",
-                                secs, usec_rem);
+        if (iter->iter_flags & TRACE_FILE_TIME_IN_NS) {
+                t = ns2usecs(iter->ts);
+                usec_rem = do_div(t, USEC_PER_SEC);
+                secs = (unsigned long)t;
+                return trace_seq_printf(s, " %5lu.%06lu: ", secs, usec_rem);
+        } else
+                return trace_seq_printf(s, " %12llu: ", iter->ts);
 }
 
 int trace_print_lat_context(struct trace_iterator *iter)
@@ -659,36 +694,29 @@ int trace_print_lat_context(struct trace_iterator *iter)
                            *next_entry = trace_find_next_entry(iter, NULL,
                                                                &next_ts);
         unsigned long verbose = (trace_flags & TRACE_ITER_VERBOSE);
-        unsigned long abs_usecs = ns2usecs(iter->ts - iter->tr->time_start);
-        unsigned long rel_usecs;
 
         /* Restore the original ent_size */
         iter->ent_size = ent_size;
 
         if (!next_entry)
                 next_ts = iter->ts;
-        rel_usecs = ns2usecs(next_ts - iter->ts);
 
         if (verbose) {
                 char comm[TASK_COMM_LEN];
 
                 trace_find_cmdline(entry->pid, comm);
 
-                ret = trace_seq_printf(s, "%16s %5d %3d %d %08x %08lx [%08llx]"
-                                       " %ld.%03ldms (+%ld.%03ldms): ", comm,
-                                       entry->pid, iter->cpu, entry->flags,
-                                       entry->preempt_count, iter->idx,
-                                       ns2usecs(iter->ts),
-                                       abs_usecs / USEC_PER_MSEC,
-                                       abs_usecs % USEC_PER_MSEC,
-                                       rel_usecs / USEC_PER_MSEC,
-                                       rel_usecs % USEC_PER_MSEC);
+                ret = trace_seq_printf(
+                                s, "%16s %5d %3d %d %08x %08lx ",
+                                comm, entry->pid, iter->cpu, entry->flags,
+                                entry->preempt_count, iter->idx);
         } else {
                 ret = lat_print_generic(s, entry, iter->cpu);
-                if (ret)
-                        ret = lat_print_timestamp(s, abs_usecs, rel_usecs);
         }
 
+        if (ret)
+                ret = lat_print_timestamp(iter, next_ts);
+
         return ret;
 }