[PATCH] fix scaled & unscaled cputime accounting

The utimescaled / stimescaled fields in the task structure and the
global cpustat should be set on all architectures. On s390 the calls
to account_user_time_scaled and account_system_time_scaled never have
been added. In addition system time that is accounted as guest time
to the user time of a process is accounted to the scaled system time
instead of the scaled user time.
To fix the bugs and to prevent future forgetfulness this patch merges
account_system_time_scaled into account_system_time and
account_user_time_scaled into account_user_time.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Michael Neuling <mikey@neuling.org>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

3 files changed, 24 insertions, 34 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index fff1c4a20b65..5b03679ff712 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4080,13 +4080,17 @@ unsigned long long task_delta_exec(struct task_struct *p)
  * Account user cpu time to a process.
  * @p: the process that the cpu time gets accounted to
  * @cputime: the cpu time spent in user space since the last update
+ * @cputime_scaled: cputime scaled by cpu frequency
  */
-void account_user_time(struct task_struct *p, cputime_t cputime)
+void account_user_time(struct task_struct *p, cputime_t cputime,
+                       cputime_t cputime_scaled)
 {
         struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
         cputime64_t tmp;
 
+        /* Add user time to process. */
         p->utime = cputime_add(p->utime, cputime);
+        p->utimescaled = cputime_add(p->utimescaled, cputime_scaled);
         account_group_user_time(p, cputime);
 
         /* Add user time to cpustat. */
@@ -4103,51 +4107,49 @@ void account_user_time(struct task_struct *p, cputime_t cputime)
  * Account guest cpu time to a process.
  * @p: the process that the cpu time gets accounted to
  * @cputime: the cpu time spent in virtual machine since the last update
+ * @cputime_scaled: cputime scaled by cpu frequency
  */
-static void account_guest_time(struct task_struct *p, cputime_t cputime)
+static void account_guest_time(struct task_struct *p, cputime_t cputime,
+                               cputime_t cputime_scaled)
 {
         cputime64_t tmp;
         struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
 
         tmp = cputime_to_cputime64(cputime);
 
+        /* Add guest time to process. */
         p->utime = cputime_add(p->utime, cputime);
+        p->utimescaled = cputime_add(p->utimescaled, cputime_scaled);
         account_group_user_time(p, cputime);
         p->gtime = cputime_add(p->gtime, cputime);
 
+        /* Add guest time to cpustat. */
         cpustat->user = cputime64_add(cpustat->user, tmp);
         cpustat->guest = cputime64_add(cpustat->guest, tmp);
 }
 
 /*
- * Account scaled user cpu time to a process.
- * @p: the process that the cpu time gets accounted to
- * @cputime: the cpu time spent in user space since the last update
- */
-void account_user_time_scaled(struct task_struct *p, cputime_t cputime)
-{
-        p->utimescaled = cputime_add(p->utimescaled, cputime);
-}
-
-/*
  * Account system cpu time to a process.
  * @p: the process that the cpu time gets accounted to
  * @hardirq_offset: the offset to subtract from hardirq_count()
  * @cputime: the cpu time spent in kernel space since the last update
+ * @cputime_scaled: cputime scaled by cpu frequency
  */
 void account_system_time(struct task_struct *p, int hardirq_offset,
-                         cputime_t cputime)
+                         cputime_t cputime, cputime_t cputime_scaled)
 {
         struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
         struct rq *rq = this_rq();
         cputime64_t tmp;
 
         if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
-                account_guest_time(p, cputime);
+                account_guest_time(p, cputime, cputime_scaled);
                 return;
         }
 
+        /* Add system time to process. */
         p->stime = cputime_add(p->stime, cputime);
+        p->stimescaled = cputime_add(p->stimescaled, cputime_scaled);
         account_group_system_time(p, cputime);
 
         /* Add system time to cpustat. */
@@ -4167,17 +4169,6 @@ void account_system_time(struct task_struct *p, int hardirq_offset,
 }
 
 /*
- * Account scaled system cpu time to a process.
- * @p: the process that the cpu time gets accounted to
- * @hardirq_offset: the offset to subtract from hardirq_count()
- * @cputime: the cpu time spent in kernel space since the last update
- */
-void account_system_time_scaled(struct task_struct *p, cputime_t cputime)
-{
-        p->stimescaled = cputime_add(p->stimescaled, cputime);
-}
-
-/*
  * Account for involuntary wait time.
  * @p: the process from which the cpu time has been stolen
  * @steal: the cpu time spent in involuntary wait
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 8f3fc2582d38..1f2fce2479fe 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -420,6 +420,7 @@ void tick_nohz_restart_sched_tick(void)
         int cpu = smp_processor_id();
         struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
         unsigned long ticks;
+        cputime_t cputime;
         ktime_t now;
 
         local_irq_disable();
@@ -452,8 +453,8 @@ void tick_nohz_restart_sched_tick(void)
          */
         if (ticks && ticks < LONG_MAX) {
                 add_preempt_count(HARDIRQ_OFFSET);
-                account_system_time(current, HARDIRQ_OFFSET,
-                                    jiffies_to_cputime(ticks));
+                cputime = jiffies_to_cputime(ticks);
+                account_system_time(current, HARDIRQ_OFFSET, cputime, cputime);
                 sub_preempt_count(HARDIRQ_OFFSET);
         }
 
diff --git a/kernel/timer.c b/kernel/timer.c
index 566257d1dc10..b5efb528aa1d 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -1023,13 +1023,11 @@ void account_process_tick(struct task_struct *p, int user_tick)
 {
         cputime_t one_jiffy = jiffies_to_cputime(1);
 
-        if (user_tick) {
-                account_user_time(p, one_jiffy);
-                account_user_time_scaled(p, cputime_to_scaled(one_jiffy));
-        } else {
-                account_system_time(p, HARDIRQ_OFFSET, one_jiffy);
-                account_system_time_scaled(p, cputime_to_scaled(one_jiffy));
-        }
+        if (user_tick)
+                account_user_time(p, one_jiffy, cputime_to_scaled(one_jiffy));
+        else
+                account_system_time(p, HARDIRQ_OFFSET, one_jiffy,
+                                    cputime_to_scaled(one_jiffy));
 }
 #endif