sched: Refactor account_system_time separating id-update

Refactor account_system_time, to separate out the logic of
identifying the update needed and code that does actual update.

This is used by following patch for IRQ_TIME_ACCOUNTING,
which has different identification logic and same update logic.

Tested-by: Shaun Ruffell <sruffell@digium.com>
Signed-off-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1292980144-28796-4-git-send-email-venki@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/sched.c b/kernel/sched.c
index 8b89b3bba565808b708153b42eeba8c73b41b811..e3fa92106ed71f876563c5a5cd4f6c1fff407f31 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3567,6 +3567,32 @@ static void account_guest_time(struct task_struct *p, cputime_t cputime,
        }
 }
 
+/*
+ * Account system cpu time to a process and desired cpustat field
+ * @p: the process that the cpu time gets accounted to
+ * @cputime: the cpu time spent in kernel space since the last update
+ * @cputime_scaled: cputime scaled by cpu frequency
+ * @target_cputime64: pointer to cpustat field that has to be updated
+ */
+static inline
+void __account_system_time(struct task_struct *p, cputime_t cputime,
+                       cputime_t cputime_scaled, cputime64_t *target_cputime64)
+{
+       cputime64_t tmp = cputime_to_cputime64(cputime);
+
+       /* 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. */
+       *target_cputime64 = cputime64_add(*target_cputime64, tmp);
+       cpuacct_update_stats(p, CPUACCT_STAT_SYSTEM, cputime);
+
+       /* Account for system time used */
+       acct_update_integrals(p);
+}
+
 /*
  * Account system cpu time to a process.
  * @p: the process that the cpu time gets accounted to
@@ -3578,31 +3604,21 @@ void account_system_time(struct task_struct *p, int hardirq_offset,
                         cputime_t cputime, cputime_t cputime_scaled)
 {
        struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
-       cputime64_t tmp;
+       cputime64_t *target_cputime64;
 
        if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
                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. */
-       tmp = cputime_to_cputime64(cputime);
        if (hardirq_count() - hardirq_offset)
-               cpustat->irq = cputime64_add(cpustat->irq, tmp);
+               target_cputime64 = &cpustat->irq;
        else if (in_serving_softirq())
-               cpustat->softirq = cputime64_add(cpustat->softirq, tmp);
+               target_cputime64 = &cpustat->softirq;
        else
-               cpustat->system = cputime64_add(cpustat->system, tmp);
+               target_cputime64 = &cpustat->system;
 
-       cpuacct_update_stats(p, CPUACCT_STAT_SYSTEM, cputime);
-
-       /* Account for system time used */
-       acct_update_integrals(p);
+       __account_system_time(p, cputime, cputime_scaled, target_cputime64);
 }
 
 /*