Re: [git] CFS-devel, latest code

Srivatsa Vaddagiri
2007-09-25T10:18:43Z

On Tue, Sep 25, 2007 at 12:10:44PM +0200, Ingo Molnar wrote:
> So the patch below just removes the is_same_group() condition. But i can
> still see bad (and obvious) latencies with Mike's 2-hogs test:
>
> taskset 01 perl -e 'while (1) {}' &
> nice -19 taskset 02 perl -e 'while (1) {}' &
>
> So something's amiss.

While I try recreating this myself, I wonder if this patch helps?

---
kernel/sched_fair.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)

Index: current/kernel/sched_fair.c
===================================================================
--- current.orig/kernel/sched_fair.c
+++ current/kernel/sched_fair.c
@@ -794,7 +794,8 @@ static void yield_task_fair(struct rq *r
static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
{
struct task_struct *curr = rq->curr;
- struct cfs_rq *cfs_rq = task_cfs_rq(curr);
+ struct cfs_rq *cfs_rq = task_cfs_rq(curr), *pcfs_rq;
+ struct sched_entity *se = &curr->se, *pse = &p->se;

if (unlikely(rt_prio(p->prio))) {
update_rq_clock(rq);
@@ -802,11 +803,19 @@ static void check_preempt_wakeup(struct
resched_task(curr);
return;
}
- if (is_same_group(curr, p)) {
- s64 delta = curr->se.vruntime - p->se.vruntime;

- if (delta > (s64)sysctl_sched_wakeup_granularity)
- resched_task(curr);
+ for_each_sched_entity(se) {
+ cfs_rq = cfs_rq_of(se);
+ pcfs_rq = cfs_rq_of(pse);
+
+ if (cfs_rq == pcfs_rq) {
+ s64 delta = se->vruntime - pse->vruntime;
+
+ if (delta > (s64)sysctl_sched_wakeup_granularity)
+ resched_task(curr);
+ break;
+ }
+ pse = pse->parent;
}
}

--
Regards,
vatsa