mirror of https://lore.kernel.org/lkml/
 help / color / mirror / Atom feed
From: Tejun Heo <tj@kernel.org>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Kent Overstreet <koverstreet@google.com>,
	linux-kernel@vger.kernel.org, Zach Brown <zab@redhat.com>,
	Felipe Balbi <balbi@ti.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Mark Fasheh <mfasheh@suse.com>, Joel Becker <jlbec@evilplan.org>,
	Jens Axboe <axboe@kernel.dk>,
	Asai Thambi S P <asamymuthupa@micron.com>,
	Selvan Mani <smani@micron.com>,
	Sam Bradshaw <sbradshaw@micron.com>,
	Jeff Moyer <jmoyer@redhat.com>, Al Viro <viro@zeniv.linux.org.uk>,
	Benjamin LaHaise <bcrl@kvack.org>,
	Oleg Nesterov <oleg@redhat.com>,
	Christoph Lameter <cl@linux-foundation.org>,
	Ingo Molnar <mingo@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Paul McKenney <paul.mckenney@us.ibm.com>
Subject: Re: [PATCH] Generic percpu refcounting
Date: Wed, 5 Jun 2013 00:44:12 -0700	[thread overview]
Message-ID: <20130605074412.GE7303@mtj.dyndns.org> (raw)
In-Reply-To: <87d2s1rowi.fsf@rustcorp.com.au>

On Wed, Jun 05, 2013 at 05:05:09PM +0930, Rusty Russell wrote:
> I think this should be rcu_read_lock(), which is currently equivalent
> but theoretically different.

I suggested using preempt_disable/enable() along with sched RCU.  I
thought that was better for some reason but I was probably
misremembering something.  rcu_read_lock/unlock() w/ synchronize_rcu()
should be fine too.  I don't care either way.

> Does your percpu_ref_kill() *really* need to be nonblocking?  (I'd have
> to read your other patches which use this to be sure).  Otherwise, just
> use synchronize_rcu(), and get rid of the release function...

synchronize_rcu() can always become problematic and should always be
avoided for generic things which may be used in various ways.  They
develop into very long latencies pretty quickly when chained back to
back.

Thanks.

-- 
tejun

      reply	other threads:[~2013-06-05  7:44 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-05-31 22:26 Kent Overstreet
2013-06-03 22:39 ` Tejun Heo
2013-06-03 23:02 ` [PATCH] percpu-refcount: Don't use silly cmpxchg() Kent Overstreet
2013-06-03 23:09   ` Tejun Heo
2013-06-05  7:35 ` [PATCH] Generic percpu refcounting Rusty Russell
2013-06-05  7:44   ` Tejun Heo [this message]

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=20130605074412.GE7303@mtj.dyndns.org \
    --to=tj@kernel.org \
    --cc=akpm@linux-foundation.org \
    --cc=asamymuthupa@micron.com \
    --cc=axboe@kernel.dk \
    --cc=balbi@ti.com \
    --cc=bcrl@kvack.org \
    --cc=cl@linux-foundation.org \
    --cc=gregkh@linuxfoundation.org \
    --cc=jlbec@evilplan.org \
    --cc=jmoyer@redhat.com \
    --cc=koverstreet@google.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mfasheh@suse.com \
    --cc=mingo@redhat.com \
    --cc=oleg@redhat.com \
    --cc=paul.mckenney@us.ibm.com \
    --cc=rusty@rustcorp.com.au \
    --cc=sbradshaw@micron.com \
    --cc=smani@micron.com \
    --cc=viro@zeniv.linux.org.uk \
    --cc=zab@redhat.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®