linux-kernel - Re: [patch] sched/fair: Move se->vruntime normalization state into struct sched

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Date:	Mon, 23 May 2016 18:13:28 +0800
From:	Wanpeng Li <kernellwp@...il.com>
To:	Mike Galbraith <umgwanakikbuti@...il.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Pavan Kondeti <pkondeti@...eaurora.org>,
	Ben Segall <bsegall@...gle.com>,
	Matt Fleming <matt@...eblueprint.co.uk>,
	Morten Rasmussen <morten.rasmussen@....com>,
	Paul Turner <pjt@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Byungchul Park <byungchul.park@....com>,
	Andrew Hunter <ahh@...gle.com>
Subject: Re: [patch] sched/fair: Move se->vruntime normalization state into
 struct sched_entity

2016-05-23 17:40 GMT+08:00 Mike Galbraith <umgwanakikbuti@...il.com>:
> On Mon, 2016-05-23 at 11:19 +0200, Peter Zijlstra wrote:
>> On Sun, May 22, 2016 at 09:00:01AM +0200, Mike Galbraith wrote:
>> > On Sat, 2016-05-21 at 21:00 +0200, Mike Galbraith wrote:
>> > > On Sat, 2016-05-21 at 16:04 +0200, Mike Galbraith wrote:
>> > >
>> > > > Wakees that were not migrated/normalized eat an unwanted min_vruntime,
>> > > > and likely take a size XXL latency hit.  Big box running master bled
>> > > > profusely under heavy load until I turned TTWU_QUEUE off.
>> >
>> > May as well make it official and against master.today.  Fly or die
>> > little patchlet.
>> >
>> > sched/fair: Move se->vruntime normalization state into struct sched_entity
>>
>> Does this work?
>
> Yup, bugs--.  Kinda funny, I considered ~this way first, but thought
> you'd not that approach.. dang, got it back-assward ;-)
>

Nicer this one.

Reviewed-by: Wanpeng Li <wanpeng.li@...mail.com>

>> ---
>>  include/linux/sched.h |  1 +
>>  kernel/sched/core.c   | 18 +++++++++++-------
>>  2 files changed, 12 insertions(+), 7 deletions(-)
>>
>> diff --git a/include/linux/sched.h b/include/linux/sched.h
>> index 1b43b45a22b9..a2001e01b3df 100644
>> --- a/include/linux/sched.h
>> +++ b/include/linux/sched.h
>> @@ -1534,6 +1534,7 @@ struct task_struct {
>>       unsigned sched_reset_on_fork:1;
>>       unsigned sched_contributes_to_load:1;
>>       unsigned sched_migrated:1;
>> +     unsigned sched_remote_wakeup:1;
>>       unsigned :0; /* force alignment to the next boundary */
>>
>>       /* unserialized, strictly 'current' */
>> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
>> index 404c0784b1fc..7f2cae4620c7 100644
>> --- a/kernel/sched/core.c
>> +++ b/kernel/sched/core.c
>> @@ -1768,13 +1768,15 @@ void sched_ttwu_pending(void)
>>       cookie = lockdep_pin_lock(&rq->lock);
>>
>>       while (llist) {
>> +             int wake_flags = 0;
>> +
>>               p = llist_entry(llist, struct task_struct,
>> wake_entry);
>>               llist = llist_next(llist);
>> -             /*
>> -              * See ttwu_queue(); we only call
>> ttwu_queue_remote() when
>> -              * its a x-cpu wakeup.
>> -              */
>> -             ttwu_do_activate(rq, p, WF_MIGRATED, cookie);
>> +
>> +             if (p->sched_remote_wakeup)
>> +                     wake_flags = WF_MIGRATED;
>> +
>> +             ttwu_do_activate(rq, p, wake_flags, cookie);
>>       }
>>
>>       lockdep_unpin_lock(&rq->lock, cookie);
>> @@ -1819,10 +1821,12 @@ void scheduler_ipi(void)
>>       irq_exit();
>>  }
>>
>> -static void ttwu_queue_remote(struct task_struct *p, int cpu)
>> +static void ttwu_queue_remote(struct task_struct *p, int cpu, int
>> wake_flags)
>>  {
>>       struct rq *rq = cpu_rq(cpu);
>>
>> +     p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED);
>> +
>>       if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) {
>>               if (!set_nr_if_polling(rq->idle))
>>                       smp_send_reschedule(cpu);
>> @@ -1869,7 +1873,7 @@ static void ttwu_queue(struct task_struct *p,
>> int cpu, int wake_flags)
>>  #if defined(CONFIG_SMP)
>>       if (sched_feat(TTWU_QUEUE) &&
>> !cpus_share_cache(smp_processor_id(), cpu)) {
>>               sched_clock_cpu(cpu); /* sync clocks x-cpu */
>> -             ttwu_queue_remote(p, cpu);
>> +             ttwu_queue_remote(p, cpu, wake_flags);
>>               return;
>>       }
>>  #endif



-- 
Regards,
Wanpeng Li