[tip:sched/core] sched: Add a PF flag for ksoftirqd identification

tip-bot for Venkatesh Pallipadi
2010-10-18T19:26:04Z

Commit-ID: 6cdd5199daf0cb7b0fcc8dca941af08492612887
Gitweb: http://git.kernel.org/tip/6cdd5199daf0cb7b0fcc8dca941af08492612887
Author: Venkatesh Pallipadi <venki@google.com>
AuthorDate: Mon, 4 Oct 2010 17:03:18 -0700
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Mon, 18 Oct 2010 20:52:22 +0200

sched: Add a PF flag for ksoftirqd identification

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 | 1 +
kernel/softirq.c | 1 +
2 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 8744e50..aca0ce6 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -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 */
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 988dfbe..267f7b7 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -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()) {