From: Tejun Heo <tj@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Herbert Xu" <herbert@gondor.apana.org.au>,
"David Miller" <davem@davemloft.net>,
"Cong Wang" <cwang@twopensource.com>,
tom@herbertland.com, kafai@fb.com, kernel-team@fb.com,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
"Network Development" <netdev@vger.kernel.org>,
"Jiří Pírko" <jiri@resnulli.us>,
"Nicolas Dichtel" <nicolas.dichtel@6wind.com>,
"Thomas Graf" <tgraf@suug.ch>,
"Scott Feldman" <sfeldma@gmail.com>
Subject: Re: [PATCH v2] netlink: Replace rhash_portid with bound
Date: Tue, 22 Sep 2015 14:53:57 -0400 [thread overview]
Message-ID: <20150922185357.GD17659@mtj.duckdns.org> (raw)
In-Reply-To: <CA+55aFyvPLD5tNsuxFAA4GgOZpamULJe7R90dXf5qSC6aBYzTw@mail.gmail.com>
Hello, Linus.
On Tue, Sep 22, 2015 at 11:42:33AM -0700, Linus Torvalds wrote:
...
> smp_rmb() should generally be about the same cost as an acquire. It
> can go either way.
>
> So *if* the algorithm is amenable to smp_wmb()/smp_rmb() kind of
> barriers, that's actually quite possibly better than acquire/release.
I see. The write path here is cold so the competition is between rmb
and acquire. Unless some significant archs completely screwed it up,
acquire still seems like the better option. It's essentially free on
x86 after all.
Thanks.
--
tejun
next prev parent reply other threads:[~2015-09-22 18:54 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-17 2:29 Possible netlink autobind regression Tejun Heo
2015-09-17 3:08 ` Herbert Xu
2015-09-17 3:41 ` Herbert Xu
2015-09-17 5:02 ` Cong Wang
2015-09-17 5:15 ` Herbert Xu
2015-09-17 11:25 ` Thomas Graf
2015-09-17 11:30 ` Tejun Heo
2015-09-18 6:36 ` [PATCH v3] netlink: Fix autobind race condition that leads to zero port ID Herbert Xu
2015-09-18 11:16 ` [PATCH v4] " Herbert Xu
2015-09-21 5:55 ` David Miller
2015-09-21 6:06 ` Herbert Xu
2015-09-21 6:11 ` David Miller
2015-09-21 13:34 ` netlink: Replace rhash_portid with bound Herbert Xu
2015-09-21 18:20 ` Tejun Heo
2015-09-22 3:38 ` [PATCH v2] " Herbert Xu
2015-09-22 16:10 ` Tejun Heo
2015-09-22 18:42 ` Linus Torvalds
2015-09-22 18:53 ` Tejun Heo [this message]
2015-09-22 19:28 ` Linus Torvalds
2015-09-22 19:50 ` Tejun Heo
2015-09-22 20:03 ` Linus Torvalds
2015-09-22 20:36 ` Bjørn Mork
2015-09-22 21:04 ` Linus Torvalds
2015-09-23 6:13 ` Herbert Xu
2015-09-23 15:54 ` Tejun Heo
2015-09-24 2:30 ` Herbert Xu
2015-09-24 2:46 ` Tejun Heo
2015-09-24 2:54 ` Herbert Xu
2015-09-24 3:06 ` Tejun Heo
2015-09-24 3:21 ` Herbert Xu
2015-09-24 3:29 ` Tejun Heo
2015-09-24 3:31 ` Herbert Xu
2015-09-24 3:41 ` Tejun Heo
2015-09-24 3:42 ` Herbert Xu
2015-09-24 3:43 ` Tejun Heo
2015-09-24 3:44 ` Herbert Xu
2015-09-24 19:11 ` David Miller
2015-09-24 20:05 ` Tejun Heo
2015-09-25 1:43 ` netlink: Add barrier to netlink_connect for theoretical case Herbert Xu
2015-09-25 3:24 ` Linus Torvalds
2015-09-25 3:39 ` Herbert Xu
2015-09-25 15:09 ` Tejun Heo
2015-09-25 15:01 ` Tejun Heo
2015-09-26 13:16 ` netlink: Add netlink_bound helper and use it in netlink_getname Herbert Xu
2015-09-26 18:09 ` Tejun Heo
2015-09-26 19:41 ` Herbert Xu
2015-09-26 19:45 ` Tejun Heo
2015-09-26 19:49 ` Herbert Xu
2015-09-26 19:52 ` Tejun Heo
2015-09-26 19:55 ` Herbert Xu
2015-09-26 20:05 ` Tejun Heo
2015-09-26 20:10 ` Herbert Xu
2015-09-26 20:17 ` Tejun Heo
2015-09-21 20:52 ` [PATCH] netlink: Replace rhash_portid with load_acquire protected boolean Tejun Heo
2015-09-18 13:37 ` [PATCH v3] netlink: Fix autobind race condition that leads to zero port ID Tejun Heo
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