sched: Add a PF flag for ksoftirqd identification
Venkatesh Pallipadi [Tue, 5 Oct 2010 00:03:18 +0000 (17:03 -0700)]
To account softirq time cleanly in scheduler, we need to identify whether
softirq is invoked in ksoftirqd context or softirq at hardirq tail context.
Add PF_KSOFTIRQD for that purpose.

As all PF flag bits are currently taken, create space by moving one of the
infrequently used bits (PF_THREAD_BOUND) down in task_struct to be along
with some other state fields.

Signed-off-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1286237003-12406-4-git-send-email-venki@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/sched.h
kernel/softirq.c

index 8744e50..aca0ce6 100644 (file)
@@ -1682,6 +1682,7 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *
 /*
  * Per process flags
  */
+#define PF_KSOFTIRQD   0x00000001      /* I am ksoftirqd */
 #define PF_STARTING    0x00000002      /* being created */
 #define PF_EXITING     0x00000004      /* getting shut down */
 #define PF_EXITPIDONE  0x00000008      /* pi exit done on shut down */
index 988dfbe..267f7b7 100644 (file)
@@ -713,6 +713,7 @@ static int run_ksoftirqd(void * __bind_cpu)
 {
        set_current_state(TASK_INTERRUPTIBLE);
 
+       current->flags |= PF_KSOFTIRQD;
        while (!kthread_should_stop()) {
                preempt_disable();
                if (!local_softirq_pending()) {