Messages in this thread Patch in this message | | | Subject | Re: oltp ~10% regression with 2.6.27-rc5 on stoakley machine | From | Lin Ming <> | Date | Fri, 26 Sep 2008 10:00:27 +0800 |
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This patch restores ~5% performance.
kernel peformance ----------------------------------- 27-rc4 100% 27-rc5 89.6% 27-rc5+peter's patch 94.5%
Thanks, Lin Ming
On Sat, 2008-09-20 at 15:38 -0600, Peter Zijlstra wrote: > > > > ------- Comment #4 from ming.m.lin@intel.com 2008-09-17 17:55 ------- > > sched_switch trace of oltp in 2.6.27-rc4 > > http://myfreefilehosting.com/f/fc6c8eaacf_1.31MB > > > > sched_switch trace of oltp in 2.6.27-rc5 > > http://myfreefilehosting.com/f/a2f9aea1b0_0.42MB > > > > Compared the 2 trace files, you can find that (at most time), > > with 2.6.27-rc5, mysql switches to sysbench when it's going to sleep > > mysqld-3791 [07] 151.421836: 3791:120:R + 3803:120:S > > mysqld-3791 [07] 151.421876: 3791:120:S ==> 3803:120:R > > sysbench-3803 [07] 151.421878: 3803:120:R + 3791:120:S > > sysbench-3803 [07] 151.421887: 3803:120:S ==> 3791:120:R > > > > with 2.6.27-rc4, mysql switches to sysbench when it's still running > > mysqld-3674 [07] 95.960220: 3674:120:R + 3687:120:S > > mysqld-3674 [07] 95.960220: 3674:120:R ==> 3687:120:R > > sysbench-3687 [07] 95.960220: 3687:120:S ==> 3674:120:R > > > > So with 2.6.27-rc5, sysbench wakes up mysql and then switches to it (mysql is > > in sleep state) > > > > With 2.6.27-rc4, sysbench switches to mysql, no need to wake up it (mysql is > > still in running state) > > Ming, how does this work for you? > > --- > Subject: sched: wakeup preempt when small overlap > > Aggresively preempt a task if its avg overlap is very small, this should > avoid the task going to sleep and find it still running when we schedule > back to it - saving a wakeup. > > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> > --- > diff --git a/include/linux/sched.h b/include/linux/sched.h > index 7b4592c..cb44774 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -897,7 +897,7 @@ struct sched_class { > void (*yield_task) (struct rq *rq); > int (*select_task_rq)(struct task_struct *p, int sync); > > - void (*check_preempt_curr) (struct rq *rq, struct task_struct *p); > + void (*check_preempt_curr) (struct rq *rq, struct task_struct *p, int sync); > > struct task_struct * (*pick_next_task) (struct rq *rq); > void (*put_prev_task) (struct rq *rq, struct task_struct *p); > diff --git a/kernel/sched.c b/kernel/sched.c > index 32d56d6..e17d506 100644 > --- a/kernel/sched.c > +++ b/kernel/sched.c > @@ -609,9 +609,9 @@ struct rq { > > static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); > > -static inline void check_preempt_curr(struct rq *rq, struct task_struct *p) > +static inline void check_preempt_curr(struct rq *rq, struct task_struct *p, int sync) > { > - rq->curr->sched_class->check_preempt_curr(rq, p); > + rq->curr->sched_class->check_preempt_curr(rq, p, sync); > } > > static inline int cpu_of(struct rq *rq) > @@ -2299,7 +2299,7 @@ out_activate: > > out_running: > trace_sched_wakeup(rq, p); > - check_preempt_curr(rq, p); > + check_preempt_curr(rq, p, sync); > > p->state = TASK_RUNNING; > #ifdef CONFIG_SMP > @@ -2432,7 +2432,7 @@ void wake_up_new_task(struct task_struct *p, unsigned long clone_flags) > inc_nr_running(rq); > } > trace_sched_wakeup_new(rq, p); > - check_preempt_curr(rq, p); > + check_preempt_curr(rq, p, 0); > #ifdef CONFIG_SMP > if (p->sched_class->task_wake_up) > p->sched_class->task_wake_up(rq, p); > @@ -2889,7 +2889,7 @@ static void pull_task(struct rq *src_rq, struct task_struct *p, > * Note that idle threads have a prio of MAX_PRIO, for this test > * to be always true for them. > */ > - check_preempt_curr(this_rq, p); > + check_preempt_curr(this_rq, p, 0); > } > > /* > @@ -6015,7 +6015,7 @@ static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu) > set_task_cpu(p, dest_cpu); > if (on_rq) { > activate_task(rq_dest, p, 0); > - check_preempt_curr(rq_dest, p); > + check_preempt_curr(rq_dest, p, 0); > } > done: > ret = 1; > diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c > index a10ac0b..82a907c 100644 > --- a/kernel/sched_fair.c > +++ b/kernel/sched_fair.c > @@ -1331,7 +1331,7 @@ static inline int depth_se(struct sched_entity *se) > /* > * Preempt the current task with a newly woken task if needed: > */ > -static void check_preempt_wakeup(struct rq *rq, struct task_struct *p) > +static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int sync) > { > struct task_struct *curr = rq->curr; > struct cfs_rq *cfs_rq = task_cfs_rq(curr); > @@ -1348,6 +1348,8 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p) > if (unlikely(se == pse)) > return; > > + cfs_rq_of(pse)->next = pse; > + > /* > * We can come here with TIF_NEED_RESCHED already set from new task > * wake up path. > @@ -1355,8 +1357,6 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p) > if (test_tsk_need_resched(curr)) > return; > > - cfs_rq_of(pse)->next = pse; > - > /* > * Batch tasks do not preempt (their preemption is driven by > * the tick): > @@ -1367,6 +1367,13 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p) > if (!sched_feat(WAKEUP_PREEMPT)) > return; > > + if (sched_feat(WAKEUP_OVERLAP) && sync && > + se->avg_overlap < sysctl_sched_migration_cost && > + pse->avg_overlap < sysctl_sched_migration_cost) { > + resched_task(curr); > + return; > + } > + > /* > * preemption test can be made between sibling entities who are in the > * same cfs_rq i.e who have a common parent. Walk up the hierarchy of > @@ -1649,7 +1656,7 @@ static void prio_changed_fair(struct rq *rq, struct task_struct *p, > if (p->prio > oldprio) > resched_task(rq->curr); > } else > - check_preempt_curr(rq, p); > + check_preempt_curr(rq, p, 0); > } > > /* > @@ -1666,7 +1673,7 @@ static void switched_to_fair(struct rq *rq, struct task_struct *p, > if (running) > resched_task(rq->curr); > else > - check_preempt_curr(rq, p); > + check_preempt_curr(rq, p, 0); > } > > /* Account for a task changing its policy or group. > diff --git a/kernel/sched_features.h b/kernel/sched_features.h > index 9353ca7..bf027a7 100644 > --- a/kernel/sched_features.h > +++ b/kernel/sched_features.h > @@ -11,3 +11,4 @@ SCHED_FEAT(ASYM_GRAN, 1) > SCHED_FEAT(LB_BIAS, 1) > SCHED_FEAT(LB_WAKEUP_UPDATE, 1) > SCHED_FEAT(ASYM_EFF_LOAD, 1) > +SCHED_FEAT(WAKEUP_OVERLAP, 1) > diff --git a/kernel/sched_idletask.c b/kernel/sched_idletask.c > index 3a4f92d..dec4cca 100644 > --- a/kernel/sched_idletask.c > +++ b/kernel/sched_idletask.c > @@ -14,7 +14,7 @@ static int select_task_rq_idle(struct task_struct *p, int sync) > /* > * Idle tasks are unconditionally rescheduled: > */ > -static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p) > +static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int sync) > { > resched_task(rq->idle); > } > @@ -76,7 +76,7 @@ static void switched_to_idle(struct rq *rq, struct task_struct *p, > if (running) > resched_task(rq->curr); > else > - check_preempt_curr(rq, p); > + check_preempt_curr(rq, p, 0); > } > > static void prio_changed_idle(struct rq *rq, struct task_struct *p, > @@ -93,7 +93,7 @@ static void prio_changed_idle(struct rq *rq, struct task_struct *p, > if (p->prio > oldprio) > resched_task(rq->curr); > } else > - check_preempt_curr(rq, p); > + check_preempt_curr(rq, p, 0); > } > > /* > diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c > index 04875ef..2e228bd 100644 > --- a/kernel/sched_rt.c > +++ b/kernel/sched_rt.c > @@ -787,7 +787,7 @@ static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p) > /* > * Preempt the current task with a newly woken task if needed: > */ > -static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p) > +static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int sync) > { > if (p->prio < rq->curr->prio) { > resched_task(rq->curr); > >
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