sched: Make task->start_time nanoseconds based
Simplify the timespec to nsec/usec conversions.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
diff --git a/kernel/tsacct.c b/kernel/tsacct.c
index ea6d170..975cb49 100644
--- a/kernel/tsacct.c
+++ b/kernel/tsacct.c
@@ -31,20 +31,19 @@
struct taskstats *stats, struct task_struct *tsk)
{
const struct cred *tcred;
- struct timespec uptime, ts;
cputime_t utime, stime, utimescaled, stimescaled;
- u64 ac_etime;
+ u64 delta;
BUILD_BUG_ON(TS_COMM_LEN < TASK_COMM_LEN);
- /* calculate task elapsed time in timespec */
- ktime_get_ts(&uptime);
- ts = timespec_sub(uptime, tsk->start_time);
- /* rebase elapsed time to usec (should never be negative) */
- ac_etime = timespec_to_ns(&ts);
- do_div(ac_etime, NSEC_PER_USEC);
- stats->ac_etime = ac_etime;
- stats->ac_btime = get_seconds() - ts.tv_sec;
+ /* calculate task elapsed time in nsec */
+ delta = ktime_get_ns() - tsk->start_time;
+ /* Convert to micro seconds */
+ do_div(delta, NSEC_PER_USEC);
+ stats->ac_etime = delta;
+ /* Convert to seconds for btime */
+ do_div(delta, USEC_PER_SEC);
+ stats->ac_btime = get_seconds() - delta;
if (thread_group_leader(tsk)) {
stats->ac_exitcode = tsk->exit_code;
if (tsk->flags & PF_FORKNOEXEC)