linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Will Deacon <will.deacon@arm.com>
To: Boqun Feng <boqun.feng@gmail.com>
Cc: Waiman Long <waiman.long@hpe.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	linux-kernel@vger.kernel.org, x86@kernel.org,
	linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org,
	linux-s390@vger.kernel.org, linux-arch@vger.kernel.org,
	Davidlohr Bueso <dave@stgolabs.net>,
	Jason Low <jason.low2@hp.com>, Dave Chinner <david@fromorbit.com>,
	Scott J Norton <scott.norton@hpe.com>,
	Douglas Hatch <doug.hatch@hpe.com>
Subject: Re: [RFC PATCH-tip v2 1/6] locking/osq: Make lock/unlock proper acquire/release barrier
Date: Mon, 20 Jun 2016 08:59:00 +0100	[thread overview]
Message-ID: <20160620075900.GB29165@arm.com> (raw)
In-Reply-To: <20160618084620.GA24424@insomnia>

On Sat, Jun 18, 2016 at 04:46:20PM +0800, Boqun Feng wrote:
> On Fri, Jun 17, 2016 at 02:17:27PM -0400, Waiman Long wrote:
> > keep the xchg() function as it is or use smp_store_release(&next->locked,
> > 1). So which one is a better alternative for ARM or PPC?
> > 
> 
> For PPC, I think xchg_release() + smp_store_release() is better than the 
> current code, because the former has two lwsync while the latter has two
> sync, and sync is quite expensive than lwsync on PPC.
> 
> I need to leave the ARM part to Will ;-)

I doubt there's much in it, but xchg() has DMB + release, so xchg_release +
smp_store_release is probably slightly better for us too.

Will

  reply	other threads:[~2016-06-20  8:08 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-14 22:48 [RFC PATCH-tip v2 0/6] locking/rwsem: Enable reader optimistic spinning Waiman Long
2016-06-14 22:48 ` [RFC PATCH-tip v2 1/6] locking/osq: Make lock/unlock proper acquire/release barrier Waiman Long
2016-06-15  8:04   ` Boqun Feng
2016-06-15 17:18     ` Peter Zijlstra
2016-06-15 19:01     ` Waiman Long
2016-06-16  2:19       ` Boqun Feng
2016-06-16 10:16         ` Will Deacon
2016-06-16 21:35         ` Waiman Long
2016-06-17  0:48           ` Boqun Feng
2016-06-17 15:26             ` Waiman Long
2016-06-17 15:45               ` Will Deacon
2016-06-17 18:17                 ` Waiman Long
2016-06-18  8:46                   ` Boqun Feng
2016-06-20  7:59                     ` Will Deacon [this message]
2016-06-15 16:56   ` Davidlohr Bueso
2016-06-15 17:12     ` Peter Zijlstra
2016-06-15 18:27       ` Davidlohr Bueso
2016-06-15 18:40         ` Peter Zijlstra
2016-06-15 18:56           ` Davidlohr Bueso
2016-06-17  1:11           ` Davidlohr Bueso
2016-06-17 14:28             ` Waiman Long
2016-06-17 16:29               ` Davidlohr Bueso
2016-06-17 16:46                 ` Davidlohr Bueso
2016-06-15 19:08       ` Waiman Long
2016-06-15 20:04         ` Waiman Long
2016-06-15 21:59           ` Peter Zijlstra
2016-06-14 22:48 ` [RFC PATCH-tip v2 2/6] locking/rwsem: Stop active read lock ASAP Waiman Long
2016-06-15 17:22   ` Peter Zijlstra
2016-06-15 19:17     ` Waiman Long
2016-06-16  2:14       ` Davidlohr Bueso
2016-06-16 21:25         ` Waiman Long
2016-06-14 22:48 ` [RFC PATCH-tip v2 3/6] locking/rwsem: Enable count-based spinning on reader Waiman Long
2016-06-15 17:38   ` Peter Zijlstra
2016-06-15 19:28     ` Waiman Long
2016-06-14 22:48 ` [RFC PATCH-tip v2 4/6] locking/rwsem: move down rwsem_down_read_failed function Waiman Long
2016-06-15 17:40   ` Peter Zijlstra
2016-06-15 19:21     ` Waiman Long
2016-06-14 22:48 ` [RFC PATCH-tip v2 5/6] locking/rwsem: Change RWSEM_WAITING_BIAS for better disambiguation Waiman Long
2016-06-15 17:43   ` Peter Zijlstra
2016-06-15 19:31     ` Waiman Long
2016-06-15 21:57       ` Peter Zijlstra
2016-06-15 17:45   ` Peter Zijlstra
2016-06-15 19:35     ` Waiman Long
2016-06-14 22:48 ` [RFC PATCH-tip v2 6/6] locking/rwsem: Enable spinning readers Waiman Long

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=20160620075900.GB29165@arm.com \
    --to=will.deacon@arm.com \
    --cc=boqun.feng@gmail.com \
    --cc=dave@stgolabs.net \
    --cc=david@fromorbit.com \
    --cc=doug.hatch@hpe.com \
    --cc=jason.low2@hp.com \
    --cc=linux-alpha@vger.kernel.org \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-ia64@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-s390@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=peterz@infradead.org \
    --cc=scott.norton@hpe.com \
    --cc=waiman.long@hpe.com \
    --cc=x86@kernel.org \
    /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;
as well as URLs for NNTP newsgroup(s).