Messages in this thread |  | | From | Vincent Guittot <> | Date | Sun, 31 Oct 2021 11:18:04 +0100 | Subject | Re: [PATCH v3 0/5] Improve newidle lb cost tracking and early abort |
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On Fri, 29 Oct 2021 at 19:00, Tim Chen <tim.c.chen@linux.intel.com> wrote: > > On Wed, 2021-10-27 at 10:49 +0200, Vincent Guittot wrote: > > > > > > Few problems still remain in your case if I'm not wrong: > > There is a patch that ensures that rq->next_balance is never set in > > the past. > > > > Vincent, > > Were you planning to take the patch to prevent the next_balance to be > in the past?
I can add it to this serie
> > Tim > > --- > From 2a5ebdeabbfdf4584532ef0e27d37ed75ca7dbd3 Mon Sep 17 00:00:00 2001 > From: Tim Chen <tim.c.chen@linux.intel.com> > Date: Tue, 11 May 2021 09:55:41 -0700 > Subject: [PATCH] sched: sched: Fix rq->next_balance time updated to earlier > than current time > To: hmem@eclists.intel.com > > In traces on newidle_balance(), this_rq->next_balance > time goes backward and earlier than current time jiffies, e.g. > > 11.602 ( ): probe:newidle_balance:(ffffffff810d2470) this_rq=0xffff88fe7f8aae00 next_balance=0x1004fb76c jiffies=0x1004fb739 > 11.624 ( ): probe:newidle_balance:(ffffffff810d2470) this_rq=0xffff88fe7f8aae00 next_balance=0x1004fb731 jiffies=0x1004fb739 > 13.856 ( ): probe:newidle_balance:(ffffffff810d2470) this_rq=0xffff88fe7f8aae00 next_balance=0x1004fb76c jiffies=0x1004fb73b > 13.910 ( ): probe:newidle_balance:(ffffffff810d2470) this_rq=0xffff88fe7f8aae00 next_balance=0x1004fb731 jiffies=0x1004fb73b > 14.637 ( ): probe:newidle_balance:(ffffffff810d2470) this_rq=0xffff88fe7f8aae00 next_balance=0x1004fb76c jiffies=0x1004fb73c > 14.666 ( ): probe:newidle_balance:(ffffffff810d2470) this_rq=0xffff88fe7f8aae00 next_balance=0x1004fb731 jiffies=0x1004fb73c > > It doesn't make sense to have a next_balance in the past. > Fix newidle_balance() and update_next_balance() so the next > balance time is at least jiffies+1. > --- > kernel/sched/fair.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 1d75af1ecfb4..740a0572cbf1 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -9901,7 +9901,10 @@ update_next_balance(struct sched_domain *sd, unsigned long *next_balance) > > /* used by idle balance, so cpu_busy = 0 */ > interval = get_sd_balance_interval(sd, 0); > - next = sd->last_balance + interval; > + if (time_after(jiffies+1, sd->last_balance + interval)) > + next = jiffies+1; > + else > + next = sd->last_balance + interval; > > if (time_after(*next_balance, next)) > *next_balance = next; > @@ -10681,6 +10684,8 @@ static int newidle_balance(struct rq *this_rq, struct rq_flags *rf) > > out: > /* Move the next balance forward */ > + if (time_after(jiffies+1, this_rq->next_balance)) > + this_rq->next_balance = jiffies+1; > if (time_after(this_rq->next_balance, next_balance)) > this_rq->next_balance = next_balance; > > -- > 2.20.1 > >
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