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From: "Li,Rongqing" <lirongqing@baidu.com>
To: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: "Peter Zijlstra" <peterz@infradead.org>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"juri.lelli@redhat.com" <juri.lelli@redhat.com>,
	"vincent.guittot@linaro.org" <vincent.guittot@linaro.org>,
	"dietmar.eggemann@arm.com" <dietmar.eggemann@arm.com>,
	"rostedt@goodmis.org" <rostedt@goodmis.org>,
	"bsegall@google.com" <bsegall@google.com>,
	"mgorman@suse.de" <mgorman@suse.de>,
	"bristot@redhat.co" <bristot@redhat.co>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"songmuchun@bytedance.com" <songmuchun@bytedance.com>,
	"Michal Koutný" <mkoutny@suse.com>
Subject: 答复: 答复: [PATCH][RFC] sched/cpuacct: Fix cpuacct charge
Date: Tue, 17 Aug 2021 03:55:08 +0000	[thread overview]
Message-ID: <06265d4d0df7410786d0ddb9bdbc4e4c@baidu.com> (raw)
In-Reply-To: <20210816162103.dup2hbho24wtmsgs@oracle.com>

> > diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c index
> > 893eece..48b117e 100644
> > --- a/kernel/sched/cpuacct.c
> > +++ b/kernel/sched/cpuacct.c
> > @@ -340,7 +340,12 @@ void cpuacct_charge(struct task_struct *tsk, u64
> > cputime)  {
> >         struct cpuacct *ca;
> >         int index = CPUACCT_STAT_SYSTEM;
> > -       struct pt_regs *regs = get_irq_regs() ? : task_pt_regs(tsk);
> > +       struct pt_regs *regs;
> > +
> > +       if (task_cpu(tsk) == raw_smp_processor_id())
> > +               regs = get_irq_regs() ? : task_pt_regs(tsk);
> > +       else
> > +               regs = task_pt_regs(tsk);
> >
> >         if (regs && user_mode(regs))
> >                 index = CPUACCT_STAT_USER;
> 
> It still suffers from task_pt_regs().
> 
> Why not make cpuacct use cgroup2's approach?  Remember only delta_exec
> here, then on reading cpuacct.usage_*, use cputime_adjust() to scale the
> user/sys from cpuacct_account_field().
> 

I think your suggestion is reasonable, Could you send a patch


> It's arguably more than just a fix for cgroup1, but there have been a few
> complaints about this function lately.
> 
> >         rcu_read_lock();
> >
> >         for (ca = task_ca(tsk); ca; ca = parent_ca(ca))
> >               __this_cpu_add(ca->cpuusage->usages[index], cputime);
> >
> >         rcu_read_unlock();
> 
> By the way, I think the __this_cpu_add() can be wrong in cases like you originally
> describe.  Seems like a bug in 73e6aafd9ea8 ("sched/cpuacct:
> Simplify the cpuacct code").

We find this issue too.

-Li

  reply	other threads:[~2021-08-17  3:55 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-20  6:04 Li RongQing
2021-07-29 10:19 ` Peter Zijlstra
2021-07-30  8:16   ` 答复: " Li,Rongqing
2021-08-16 16:21     ` Daniel Jordan
2021-08-17  3:55       ` Li,Rongqing [this message]
2021-08-18 15:33         ` 答复: " Daniel Jordan

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