From: Tejun Heo <tj@kernel.org>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>,
cl@linux-foundation.org, kmo@daterainc.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 6/6] percpu-refcount: implement percpu_ref_reinit() and percpu_ref_is_zero()
Date: Thu, 19 Jun 2014 09:36:24 -0400 [thread overview]
Message-ID: <20140619133624.GI11042@htj.dyndns.org> (raw)
In-Reply-To: <20140619022708.GB4669@linux.vnet.ibm.com>
Hey, Paul.
On Wed, Jun 18, 2014 at 07:27:08PM -0700, Paul E. McKenney wrote:
> Yep, smp_load_acquire() orders its load against later loads and stores,
> so it really does need a memory barrier on weakly ordered systems.
Yeap.
> This is the "publish" operation for dynamically allocated per-CPU
> references? If so, agreed, you should be able to rely on dependency
> ordering. Make sure to comment the smp_read_barrier_depends(). ;-)
Definitely, there aren't many things which are more frustrating than
barriers w/o comments explaining their pairing. I'm pairing
store_release with read_barrier_depends as that's what RCU is doing.
Is this the preferred way now? I like the new store_release and
load_acquire as they document what's being barriered better but as Lai
suggested in another reply it does seem a bit unbalanced. I wonder
whether load_acquire_depends would make sense.
Thanks.
--
tejun
next prev parent reply other threads:[~2014-06-19 13:36 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-18 1:07 [PATCHSET percpu/for-3.17] percpu: implement percpu_ref_reinit() Tejun Heo
2014-06-18 1:08 ` [PATCH 1/6] percpu-refcount, aio: use percpu_ref_cancel_init() in ioctx_alloc() Tejun Heo
2014-06-25 14:31 ` Benjamin LaHaise
2014-06-25 14:56 ` Tejun Heo
2014-06-25 15:35 ` Benjamin LaHaise
2014-06-25 15:37 ` Tejun Heo
2014-06-18 1:08 ` [PATCH 2/6] percpu-refcount: one bit is enough for REF_STATUS Tejun Heo
2014-06-18 2:37 ` Lai Jiangshan
2014-06-18 1:08 ` [PATCH 3/6] percpu-refcount: add helpers for ->percpu_count accesses Tejun Heo
2014-06-18 1:08 ` [PATCH 4/6] percpu-refcount: use unsigned long for pcpu_count pointer Tejun Heo
2014-06-18 1:08 ` [PATCH 5/6] percpu-refcount: require percpu_ref to be exited explicitly Tejun Heo
2014-06-18 1:08 ` [PATCH 6/6] percpu-refcount: implement percpu_ref_reinit() and percpu_ref_is_zero() Tejun Heo
2014-06-18 3:37 ` Lai Jiangshan
2014-06-18 15:32 ` Tejun Heo
2014-06-19 1:58 ` Lai Jiangshan
2014-06-19 2:07 ` Tejun Heo
2014-06-19 2:27 ` Paul E. McKenney
2014-06-19 13:36 ` Tejun Heo [this message]
2014-06-19 17:05 ` Paul E. McKenney
2014-06-19 19:06 ` Tejun Heo
2014-06-19 21:07 ` Paul E. McKenney
2014-06-19 2:20 ` [PATCH v2 " Tejun Heo
2014-06-19 3:01 ` Lai Jiangshan
2014-06-19 13:31 ` Tejun Heo
2014-06-19 16:55 ` Paul E. McKenney
2014-06-19 17:03 ` Paul E. McKenney
2014-06-19 19:06 ` Tejun Heo
2014-06-28 12:10 ` [PATCHSET percpu/for-3.17] percpu: implement percpu_ref_reinit() Tejun Heo
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=20140619133624.GI11042@htj.dyndns.org \
--to=tj@kernel.org \
--cc=cl@linux-foundation.org \
--cc=kmo@daterainc.com \
--cc=laijs@cn.fujitsu.com \
--cc=linux-kernel@vger.kernel.org \
--cc=paulmck@linux.vnet.ibm.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®