From: Peter Zijlstra <peterz@infradead.org>
To: Cheng Chao <cs.os.kernel@gmail.com>
Cc: mingo@kernel.org, oleg@redhat.com, tj@kernel.org,
akpm@linux-foundation.org, chris@chris-wilson.co.uk,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] stop_machine: Make migration_cpu_stop() does useful works for CONFIG_PREEMPT_NONE
Date: Tue, 13 Sep 2016 10:45:52 +0200 [thread overview]
Message-ID: <20160913084552.GG5008@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <54e0445d-87a5-2eb3-2a7e-7521bc58f095@gmail.com>
On Tue, Sep 13, 2016 at 12:03:05PM +0800, Cheng Chao wrote:
>
> Peter, Is it as a new patch?
I wanted both changes in one pathc, but I fudged my git-diff.
> > ---
> > kernel/stop_machine.c | 5 +++++
> > 1 file changed, 5 insertions(+)
> >
> > diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
> > index ae6f41fb9cba..637798d6b554 100644
> > --- a/kernel/stop_machine.c
> > +++ b/kernel/stop_machine.c
> > @@ -121,6 +121,11 @@ int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
> > cpu_stop_init_done(&done, 1);
> > if (!cpu_stop_queue_work(cpu, &work))
> > return -ENOENT;
> > + /*
> > + * In case @cpu == smp_proccessor_id() we can avoid a sleep+wakeup
> > + * by doing a preemption.
> > + */
> > + cond_resched();
> > wait_for_completion(&done.completion);
> > return done.ret;
> > }
> >
>
> I agree to use cond_resched(). https://lkml.org/lkml/2016/9/12/1228
>
> so we really don't need "if defined(CONFIG_PREEMPT_NONE)"?
> I also think without the "if defined(CONFIG_PREEMPT_NONE)",
> the code is more clean,and the logic is still ok.
You really don't need the #ifdef, look at the actual code, not the
Kconfig language.
next prev parent reply other threads:[~2016-09-13 8:46 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <OF73BCE1E4.D2224FEC-ON48258025.0022CFA7-48258025.0022E3DC@kedacom.com>
2016-09-09 8:13 ` [PATCH v2] stop_machine: Make migration_cpu_stop() does useful works for CONFIG_PREEMPT_NONE Cheng Chao
2016-09-09 8:19 ` chengchao
2016-09-09 13:14 ` Oleg Nesterov
2016-09-09 16:24 ` Peter Zijlstra
2016-09-10 8:52 ` [PATCH v3] " Cheng Chao
2016-09-10 9:51 ` Cheng Chao
2016-09-10 16:33 ` Peter Zijlstra
2016-09-12 11:03 ` Oleg Nesterov
2016-09-13 2:45 ` Cheng Chao
2016-09-12 11:37 ` Peter Zijlstra
2016-09-12 11:41 ` Peter Zijlstra
2016-09-12 13:05 ` Oleg Nesterov
2016-09-12 15:01 ` Peter Zijlstra
2016-09-13 16:14 ` Oleg Nesterov
2016-09-13 16:37 ` Peter Zijlstra
2016-09-14 2:07 ` Cheng Chao
2016-09-14 7:50 ` Peter Zijlstra
2016-09-14 15:45 ` Oleg Nesterov
2016-09-22 13:59 ` [tip:sched/core] sched/core: Optimize __schedule() tip-bot for Peter Zijlstra
2016-09-13 4:03 ` [PATCH v3] stop_machine: Make migration_cpu_stop() does useful works for CONFIG_PREEMPT_NONE Cheng Chao
2016-09-13 8:45 ` Peter Zijlstra [this message]
2016-09-14 2:01 ` [PATCH v4] stop_machine: Avoid a sleep and wakeup in the stop_one_cpu() Cheng Chao
2016-09-14 15:53 ` Oleg Nesterov
2016-09-18 2:07 ` Cheng Chao
2016-09-22 13:59 ` [tip:sched/core] stop_machine: Avoid a sleep and wakeup in stop_one_cpu() tip-bot for Cheng Chao
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