From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752959Ab2GAGyR (ORCPT ); Sun, 1 Jul 2012 02:54:17 -0400 Received: from ozlabs.org ([203.10.76.45]:38967 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752192Ab2GAGyN (ORCPT ); Sun, 1 Jul 2012 02:54:13 -0400 From: Rusty Russell To: "Paul E. McKenney" , linux-kernel@vger.kernel.org Cc: mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com, fweisbec@gmail.com, sbw@mit.edu, patches@linaro.org, "Paul E. McKenney" Subject: Re: [PATCH tip/core/rcu 01/22] rcu: Control RCU_FANOUT_LEAF from boot-time parameter In-Reply-To: <1340378241-6458-1-git-send-email-paulmck@linux.vnet.ibm.com> References: <20120622151655.GA6249@linux.vnet.ibm.com> <1340378241-6458-1-git-send-email-paulmck@linux.vnet.ibm.com> User-Agent: Notmuch/0.12 (http://notmuchmail.org) Emacs/23.3.1 (i686-pc-linux-gnu) Date: Sun, 01 Jul 2012 15:49:42 +0930 Message-ID: <87y5n4xatd.fsf@rustcorp.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 22 Jun 2012 08:17:00 -0700, "Paul E. McKenney" wrote: > From: "Paul E. McKenney" > > Although making RCU_FANOUT_LEAF a kernel configuration parameter rather > than a fixed constant makes it easier for people to decrease cache-miss > overhead for large systems, it is of little help for people who must > run a single pre-built kernel binary. > > This commit therefore allows the value of RCU_FANOUT_LEAF to be > increased (but not decreased!) via a boot-time parameter named > rcutree.rcu_fanout_leaf. ... > +static int rcu_fanout_leaf = CONFIG_RCU_FANOUT_LEAF; > +module_param(rcu_fanout_leaf, int, 0); Maybe it's overkill, but 0400 or 0444 might be a nice touch. Cheers, Rusty.