LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Frederic Weisbecker <fweisbec@gmail.com>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>,
	kvm@vger.kernel.org, borntraeger@de.ibm.com,
	linux-kernel@vger.kernel.org, mtosatti@redhat.com,
	mingo@kernel.orgm, ak@linux.intel.com, oleg@redhat.com,
	masami.hiramatsu.pt@hitachi.com, lcapitulino@redhat.com,
	pbonzini@redhat.com
Subject: Re: [PATCH 1/5] rcu,nohz: add state parameter to context_tracking_user_enter/exit
Date: Sat, 7 Feb 2015 09:30:41 +0100	[thread overview]
Message-ID: <20150207083036.GA24538@lerouge> (raw)
In-Reply-To: <20150207071453.GA12268@linux.vnet.ibm.com>

On Fri, Feb 06, 2015 at 11:14:53PM -0800, Paul E. McKenney wrote:
> On Fri, Feb 06, 2015 at 10:34:21PM -0800, Paul E. McKenney wrote:
> > On Fri, Feb 06, 2015 at 10:53:34PM -0500, Rik van Riel wrote:
> > > -----BEGIN PGP SIGNED MESSAGE-----
> > > Hash: SHA1
> > > 
> > > On 02/06/2015 06:15 PM, Frederic Weisbecker wrote:
> > > 
> > > > Just a few things then:
> > > > 
> > > > 1) In this case rename context_tracking_user_enter/exit() to 
> > > > context_tracking_enter() and context_tracking_exit(), since it's
> > > > not anymore about user only but about any generic context.
> > > > 
> > > > 2) We have the "WARN_ON_ONCE(!current->mm);" condition that is a
> > > > debug check specific to userspace transitions because kernel
> > > > threads aren't expected to resume to userspace. Can we also expect
> > > > that we never switch to/from guest from a kernel thread? AFAICS
> > > > this happens from an ioctl (thus user task) in x86 for kvm. But I
> > > > only know this case.
> > > > 
> > > > 3) You might want to update a few comments that assume we only deal
> > > > with userspace transitions.
> > > > 
> > > > 4) trace_user_enter/exit() should stay user-transitions specific.
> > > 
> > > Paul, would you like me to send follow-up patches with the cleanups
> > > suggested by Frederic, or would you prefer me to send a new series
> > > with the cleanups integrated?
> > 
> > I would prefer a new series, in order to prevent possible future
> > confusion.
> 
> Of course, if Frederic would rather push them himself, I am fine with
> that.  And in that case, you should ask him for his preferences, which
> just might differ from mine.  ;-)

I prefer a new series too. Now whether you or me take the patches, I don't mind
either way :-)

Also I wonder how this feature is going to be enabled. Will it be enabled on
full dynticks or should it be a seperate feature depending on full dynticks?
Or even just CONFIG_RCU_USER_EQS? Because I'm still unclear about how and what
this is used, if it involves full dynticks or only RCU extended quiescent states.

Thanks.

  reply	other threads:[~2015-02-07  8:30 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-05 20:23 [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest riel
2015-02-05 20:23 ` [PATCH 1/5] rcu,nohz: add state parameter to context_tracking_user_enter/exit riel
2015-02-05 23:55   ` Paul E. McKenney
2015-02-06 10:15     ` Paolo Bonzini
2015-02-06 13:41       ` Paul E. McKenney
2015-02-06 17:22   ` Frederic Weisbecker
2015-02-06 18:20     ` Rik van Riel
2015-02-06 18:23       ` Frederic Weisbecker
2015-02-06 18:51         ` Rik van Riel
2015-02-06 23:15           ` Frederic Weisbecker
2015-02-07  3:53             ` Rik van Riel
2015-02-07  6:34               ` Paul E. McKenney
2015-02-07  7:14                 ` Paul E. McKenney
2015-02-07  8:30                   ` Frederic Weisbecker [this message]
2015-02-07 11:29                     ` Rik van Riel
2015-02-07 20:06                     ` Paul E. McKenney
2015-02-09 15:42                       ` Rik van Riel
2015-02-05 20:23 ` [PATCH 2/5] rcu,nohz: run vtime_user_enter/exit only when state == IN_USER riel
2015-02-05 20:23 ` [PATCH 3/5] nohz,kvm: export context_tracking_user_enter/exit riel
2015-02-05 23:55   ` Paul E. McKenney
2015-02-05 20:23 ` [PATCH 4/5] kvm,rcu,nohz: use RCU extended quiescent state when running KVM guest riel
2015-02-05 23:56   ` Paul E. McKenney
2015-02-06 18:01   ` Frederic Weisbecker
2015-02-06 23:24   ` Frederic Weisbecker
2015-02-05 20:23 ` [PATCH 5/5] nohz: add stub context_tracking_is_enabled riel
2015-02-05 23:56   ` Paul E. McKenney
2015-02-06 13:46 ` [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest Frederic Weisbecker
2015-02-06 13:50   ` Paolo Bonzini
2015-02-06 16:19     ` Paul E. McKenney
2015-02-06 18:09     ` Frederic Weisbecker
2015-02-06 14:56   ` Rik van Riel
2015-02-06 18:05     ` Frederic Weisbecker
2015-02-06 15:00 ` Christian Borntraeger
2015-02-06 18:20   ` Frederic Weisbecker

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=20150207083036.GA24538@lerouge \
    --to=fweisbec@gmail.com \
    --cc=ak@linux.intel.com \
    --cc=borntraeger@de.ibm.com \
    --cc=kvm@vger.kernel.org \
    --cc=lcapitulino@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=masami.hiramatsu.pt@hitachi.com \
    --cc=mingo@kernel.orgm \
    --cc=mtosatti@redhat.com \
    --cc=oleg@redhat.com \
    --cc=paulmck@linux.vnet.ibm.com \
    --cc=pbonzini@redhat.com \
    --cc=riel@redhat.com \
    --subject='Re: [PATCH 1/5] rcu,nohz: add state parameter to context_tracking_user_enter/exit' \
    /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

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).