All of lore.kernel.org
 help / color / mirror / Atom feed
From: Peter Zijlstra <peterz@infradead.org>
To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: yong.zhang0@gmail.com, paulmck@linux.vnet.ibm.com,
	oleg@redhat.com, linux-kernel@vger.kernel.org,
	akpm@linux-foundation.org, mingo@elte.hu, lizf@cn.fujitsu.com,
	miaox@cn.fujitsu.com
Subject: Re: [PATCH v2 1/2] rcu: don't bind offline cpu
Date: Thu, 19 May 2011 10:55:01 +0200	[thread overview]
Message-ID: <1305795301.2466.7200.camel@twins> (raw)
In-Reply-To: <1305794078.2466.7193.camel@twins>

On Thu, 2011-05-19 at 10:34 +0200, Peter Zijlstra wrote:
> On Thu, 2011-05-19 at 15:06 +0900, KOSAKI Motohiro wrote:
> > 
> > The right way is, explicit two phase cpu bindings (1) bind boot
> > (or any other online) cpu at CPU_UP_PREPARE (2) bind correct
> > target cpu at CPU_ONLINE. This patch does it. 
> 
> I'm not sure that is in-fact correct. From what I understood, RCU could
> have need of this thread before the ONLINE callback and expects it to be
> affine at that time.

Right, so we're waking that thread from the timer tick, so we must have
that thread set-up and ready _before_ we enable interrupts for the first
time. CPU_ONLINE is _WAAAAAY_ too late for that.

> What was wrong with delaying the wakeup to STARTING?

Hrmm right, so I thought STARTING was right after we marked the cpu
online, but its right before. Bummer.

Also Paul:

rcu_cpu_kthread()
  rcu_process_callbacks()
    __rcu_process_callbacks()
      rcu_do_batch()
        invoke_rcu_cpu_kthread()

Why wake the thread again if its already running?



  parent reply	other threads:[~2011-05-19  8:55 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-04-28 14:20 [RFC PATCH] cpuset: fix cpuset_cpus_allowed_fallback() don't update tsk->rt.nr_cpus_allowed KOSAKI Motohiro
2011-04-28 16:11 ` Oleg Nesterov
2011-05-02 10:42   ` KOSAKI Motohiro
2011-05-02 10:55     ` [PATCH 1/2] " KOSAKI Motohiro
2011-05-11 16:05       ` Peter Zijlstra
2011-05-13  5:48         ` KOSAKI Motohiro
2011-05-13  6:42           ` Yong Zhang
2011-05-13  7:33             ` KOSAKI Motohiro
2011-05-13  7:43               ` Yong Zhang
2011-05-13  9:34                 ` KOSAKI Motohiro
2011-05-13 17:02             ` Peter Zijlstra
2011-05-14 11:17               ` KOSAKI Motohiro
2011-05-16 13:37               ` Yong Zhang
2011-05-19  8:45                 ` Peter Zijlstra
2011-05-19  8:54                   ` Yong Zhang
2011-05-15 18:55             ` Paul E. McKenney
2011-05-16 13:26               ` Yong Zhang
2011-05-19  6:06                 ` [PATCH v2 1/2] rcu: don't bind offline cpu KOSAKI Motohiro
2011-05-19  6:08                   ` [PATCH v2 2/2] cpuset: fix cpuset_cpus_allowed_fallback() don't update tsk->rt.nr_cpus_allowed KOSAKI Motohiro
2011-05-28 16:35                     ` [tip:sched/urgent] cpuset: Fix cpuset_cpus_allowed_fallback(), " tip-bot for KOSAKI Motohiro
2011-06-20 10:20                       ` Peter Zijlstra
2011-06-21  9:54                         ` KOSAKI Motohiro
2011-05-19  8:34                   ` [PATCH v2 1/2] rcu: don't bind offline cpu Peter Zijlstra
2011-05-19  8:50                     ` KOSAKI Motohiro
2011-05-19  9:41                       ` Peter Zijlstra
2011-05-19 10:12                         ` KOSAKI Motohiro
2011-05-19 11:41                           ` Peter Zijlstra
2011-05-20 22:46                         ` Paul E. McKenney
2011-05-19  8:55                     ` Peter Zijlstra [this message]
2011-05-02 10:56     ` [PATCH 2/2] sched, cpuset: introduce do_set_cpus_allowed() helper function KOSAKI Motohiro
2011-05-02 12:58     ` [RFC PATCH] cpuset: fix cpuset_cpus_allowed_fallback() don't update tsk->rt.nr_cpus_allowed Paul E. McKenney

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1305795301.2466.7200.camel@twins \
    --to=peterz@infradead.org \
    --cc=akpm@linux-foundation.org \
    --cc=kosaki.motohiro@jp.fujitsu.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=lizf@cn.fujitsu.com \
    --cc=miaox@cn.fujitsu.com \
    --cc=mingo@elte.hu \
    --cc=oleg@redhat.com \
    --cc=paulmck@linux.vnet.ibm.com \
    --cc=yong.zhang0@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.