From: Peter Zijlstra <peterz@infradead.org>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: tglx@linutronix.de, kvm@vger.kernel.org, fweisbec@gmail.com,
jiangshanlai@gmail.com, linux-kernel@vger.kernel.org,
rostedt@goodmis.org, josh@joshtriplett.org, dhowells@redhat.com,
edumazet@google.com, netdev@vger.kernel.org,
mathieu.desnoyers@efficios.com, oleg@redhat.com,
dipankar@in.ibm.com, akpm@linux-foundation.org,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
virtualization@lists.linux-foundation.org, mingo@kernel.org
Subject: Re: [PATCH tip/core/rcu 21/21] drivers/vhost: Remove now-redundant read_barrier_depends()
Date: Tue, 5 Dec 2017 20:57:52 +0100 [thread overview]
Message-ID: <20171205195752.GS3165@worktop.lehotels.local> (raw)
In-Reply-To: <20171205215020-mutt-send-email-mst@kernel.org>
On Tue, Dec 05, 2017 at 09:51:48PM +0200, Michael S. Tsirkin wrote:
> > > WRITE_ONCE(obj->val, 1);
> > > smp_wmb();
> > > WRITE_ONCE(*foo, obj);
> >
> > I believe Peter was instead suggesting:
> >
> > WRITE_ONCE(obj->val, 1);
> > smp_store_release(foo, obj);
>
> Isn't that more expensive though?
Depends on the architecture. The only architecture where it is more
expensive and people actually still care about is ARM I think.
next prev parent reply other threads:[~2017-12-05 19:57 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20171201195053.GA23494@linux.vnet.ibm.com>
2017-12-01 19:51 ` [PATCH tip/core/rcu 21/21] drivers/vhost: Remove now-redundant read_barrier_depends() Paul E. McKenney
2017-12-05 18:31 ` Michael S. Tsirkin
[not found] ` <20171205202928-mutt-send-email-mst@kernel.org>
2017-12-05 18:39 ` Peter Zijlstra
2017-12-05 18:57 ` Michael S. Tsirkin
2017-12-05 19:17 ` Peter Zijlstra
[not found] ` <20171205191733.GQ3165@worktop.lehotels.local>
2017-12-05 19:24 ` Michael S. Tsirkin
2017-12-05 19:33 ` Paul E. McKenney
2017-12-05 19:51 ` Michael S. Tsirkin
[not found] ` <20171205215020-mutt-send-email-mst@kernel.org>
2017-12-05 19:57 ` Peter Zijlstra [this message]
2017-12-05 20:28 ` Michael S. Tsirkin
[not found] ` <20171205222757-mutt-send-email-mst@kernel.org>
2017-12-05 21:17 ` Peter Zijlstra
[not found] ` <20171205211735.GT3165@worktop.lehotels.local>
2017-12-05 21:42 ` Michael S. Tsirkin
2017-12-05 20:08 ` Paul E. McKenney
[not found] ` <20171205200801.GR7829@linux.vnet.ibm.com>
2017-12-05 21:24 ` Michael S. Tsirkin
[not found] ` <20171205222857-mutt-send-email-mst@kernel.org>
2017-12-05 21:36 ` Paul E. McKenney
[not found] ` <20171205213644.GU7829@linux.vnet.ibm.com>
2017-12-05 21:43 ` Michael S. Tsirkin
[not found] ` <20171205234308-mutt-send-email-mst@kernel.org>
2017-12-05 22:02 ` Paul E. McKenney
2017-12-05 22:09 ` Peter Zijlstra
2017-12-05 21:57 ` Peter Zijlstra
[not found] ` <20171205215700.GV3165@worktop.lehotels.local>
2017-12-05 22:09 ` Michael S. Tsirkin
[not found] ` <20171206000541-mutt-send-email-mst@kernel.org>
2017-12-05 23:39 ` Paul E. McKenney
2017-12-05 19:55 ` Peter Zijlstra
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