softirqs: Account ksoftirqd time as cpustat softirq

softirq time in ksoftirqd context is not accounted in ns granularity
per cpu softirq stats, as we want that to be a part of ksoftirqd
exec_runtime.

Accounting them as softirq on /proc/stat separately.

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: <1292980144-28796-6-git-send-email-venki@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 8 insertions, 0 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 2a3c9799d76b..8b718b59b09f 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3686,6 +3686,14 @@ static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
                 cpustat->irq = cputime64_add(cpustat->irq, tmp);
         } else if (irqtime_account_si_update()) {
                 cpustat->softirq = cputime64_add(cpustat->softirq, tmp);
+        } else if (this_cpu_ksoftirqd() == p) {
+                /*
+                 * ksoftirqd time do not get accounted in cpu_softirq_time.
+                 * So, we have to handle it separately here.
+                 * Also, p->stime needs to be updated for ksoftirqd.
+                 */
+                __account_system_time(p, cputime_one_jiffy, one_jiffy_scaled,
+                                        &cpustat->softirq);
         } else if (user_tick) {
                 account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
         } else if (p == rq->idle) {