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 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/