From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: [PATCH] netfilter: revised locking for x_tables Date: Tue, 28 Apr 2009 09:50:36 -0700 (PDT) Message-ID: References: <20090428135219.GA28513@Krystal> <20090428.073759.78537345.davem@davemloft.net> <20090428144920.GA28942@Krystal> <20090428.080031.14741305.davem@davemloft.net> <20090428092411.5331c4a1@nehalam> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: David Miller , mathieu.desnoyers@polymtl.ca, mingo@elte.hu, dada1@cosmosbay.com, zbr@ioremap.net, peterz@infradead.org, jarkao2@gmail.com, paulus@samba.org, paulmck@linux.vnet.ibm.com, kaber@trash.net, jeff.chua.linux@gmail.com, laijs@cn.fujitsu.com, jengelh@medozas.de, r000n@r000n.net, linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org, netdev@vger.kernel.org, benh@kernel.crashing.org To: Stephen Hemminger Return-path: In-Reply-To: <20090428092411.5331c4a1@nehalam> Sender: netfilter-devel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Ack. It could do with the update from Eric about how non-current CPU writelocks only require preemp-disable around get_counters() (and then the local_bh_disable() only around the current-CPU case). I _think_ get_counters() is the only case that can use that optimization, but it's quite possible that it's worth doing especially for machines with lots of cores, if BH latency is an issue (and it might be). Of course, for the lots-and-lots of cores case, even the preemption disable might be an issue. And then it really does get much more complicated. At that point, you probably want the RCU thing. Linus