[PATCH 4/4] cputime: simplify task_cputime()

Stanislaw Gruszka
2016-10-31T12:36:29Z

Now since fetch_task_cputime() has no other users than task_cputime(),
it's code could be used directly in task_cputime(). Moreover since
only 2 task_cputime() calls of 17 use NULL argument, we can
add dummy variables to those calls and remove NULL checks from
task_cputimes().

Do also remove NULL checks on task_cputimes_scaled().

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
---
arch/x86/kernel/apm_32.c | 4 +-
include/linux/sched.h | 12 +++-----
kernel/sched/cputime.c | 57 ++++++++++-----------------------------
kernel/time/posix-cpu-timers.c | 4 +-
4 files changed, 23 insertions(+), 54 deletions(-)

diff --git a/arch/x86/kernel/apm_32.c b/arch/x86/kernel/apm_32.c
index c7364bd..d90749b 100644
--- a/arch/x86/kernel/apm_32.c
+++ b/arch/x86/kernel/apm_32.c
@@ -906,14 +906,14 @@ static int apm_cpu_idle(struct cpuidle_device *dev,
static int use_apm_idle; /* = 0 */
static unsigned int last_jiffies; /* = 0 */
static unsigned int last_stime; /* = 0 */
- cputime_t stime;
+ cputime_t stime, utime;

int apm_idle_done = 0;
unsigned int jiffies_since_last_check = jiffies - last_jiffies;
unsigned int bucket;

recalc:
- task_cputime(current, NULL, &stime);
+ task_cputime(current, &utime, &stime);
if (jiffies_since_last_check > IDLE_CALC_LIMIT) {
use_apm_idle = 0;
} else if (jiffies_since_last_check > idle_period) {
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 36a2c2e..93fbae0 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2228,10 +2228,8 @@ extern void task_cputime(struct task_struct *t,
static inline void task_cputime(struct task_struct *t,
cputime_t *utime, cputime_t *stime)
{
- if (utime)
- *utime = t->utime;
- if (stime)
- *stime = t->stime;
+ *utime = t->utime;
+ *stime = t->stime;
}

static inline cputime_t task_gtime(struct task_struct *t)
@@ -2245,10 +2243,8 @@ static inline void task_cputime_scaled(struct task_struct *t,
cputime_t *utimescaled,
cputime_t *stimescaled)
{
- if (utimescaled)
- *utimescaled = t->utimescaled;
- if (stimescaled)
- *stimescaled = t->stimescaled;
+ *utimescaled = t->utimescaled;
+ *stimescaled = t->stimescaled;
}
#else
static inline void task_cputime_scaled(struct task_struct *t,
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index d427def..46a984e 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -851,29 +851,25 @@ cputime_t task_gtime(struct task_struct *t)
* add up the pending nohz execution time since the last
* cputime snapshot.
*/
-static void
-fetch_task_cputime(struct task_struct *t,
- cputime_t *u_dst, cputime_t *s_dst,
- cputime_t *u_src, cputime_t *s_src,
- cputime_t *udelta, cputime_t *sdelta)
+void task_cputime(struct task_struct *t, cputime_t *utime, cputime_t *stime)
{
+ cputime_t delta;
unsigned int seq;
- unsigned long long delta;

- do {
- *udelta = 0;
- *sdelta = 0;
+ if (!vtime_accounting_enabled()) {
+ *utime = t->utime;
+ *stime = t->stime;
+ return;
+ }

+ do {
seq = read_seqcount_begin(&t->vtime_seqcount);

- if (u_dst)
- *u_dst = *u_src;
- if (s_dst)
- *s_dst = *s_src;
+ *utime = t->utime;
+ *stime = t->stime;

/* Task is sleeping, nothing to add */
- if (t->vtime_snap_whence == VTIME_INACTIVE ||
- is_idle_task(t))
+ if (t->vtime_snap_whence == VTIME_INACTIVE || is_idle_task(t))
continue;

delta = vtime_delta(t);
@@ -882,33 +878,10 @@ cputime_t task_gtime(struct task_struct *t)
* Task runs either in user or kernel space, add pending nohz time to
* the right place.
*/
- if (t->vtime_snap_whence == VTIME_USER || t->flags & PF_VCPU) {
- *udelta = delta;
- } else {
- if (t->vtime_snap_whence == VTIME_SYS)
- *sdelta = delta;
- }
+ if (t->vtime_snap_whence == VTIME_USER || t->flags & PF_VCPU)
+ *utime += delta;
+ else if (t->vtime_snap_whence == VTIME_SYS)
+ *stime += delta;
} while (read_seqcount_retry(&t->vtime_seqcount, seq));
}
-
-
-void task_cputime(struct task_struct *t, cputime_t *utime, cputime_t *stime)
-{
- cputime_t udelta, sdelta;
-
- if (!vtime_accounting_enabled()) {
- if (utime)
- *utime = t->utime;
- if (stime)
- *stime = t->stime;
- return;
- }
-
- fetch_task_cputime(t, utime, stime, &t->utime,
- &t->stime, &udelta, &sdelta);
- if (utime)
- *utime += udelta;
- if (stime)
- *stime += sdelta;
-}
#endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index 39008d7..e887ffc 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -133,9 +133,9 @@ static inline unsigned long long prof_ticks(struct task_struct *p)
}
static inline unsigned long long virt_ticks(struct task_struct *p)
{
- cputime_t utime;
+ cputime_t utime, stime;

- task_cputime(p, &utime, NULL);
+ task_cputime(p, &utime, &stime);

return cputime_to_expires(utime);
}
--
1.7.1