From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932666AbaJ2LCK (ORCPT ); Wed, 29 Oct 2014 07:02:10 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:40275 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932259AbaJ2LCI (ORCPT ); Wed, 29 Oct 2014 07:02:08 -0400 Date: Wed, 29 Oct 2014 12:01:46 +0100 From: Peter Zijlstra To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com, Clark Williams Subject: Re: [PATCH tip/core/rcu 4/7] rcu: Unify boost and kthread priorities Message-ID: <20141029110146.GA3337@twins.programming.kicks-ass.net> References: <20141028222224.GA28263@linux.vnet.ibm.com> <1414534982-29203-1-git-send-email-paulmck@linux.vnet.ibm.com> <1414534982-29203-4-git-send-email-paulmck@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1414534982-29203-4-git-send-email-paulmck@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 28, 2014 at 03:22:59PM -0700, Paul E. McKenney wrote: > From: Clark Williams > > Rename CONFIG_RCU_BOOST_PRIO to CONFIG_RCU_KTHREAD_PRIO and use this > value for both the per-CPU kthreads (rcuc/N) and the rcu boosting > threads (rcub/n). > > Also, create the module_parameter rcutree.kthread_prio to be used on > the kernel command line at boot to set a new value (rcutree.kthread_prio=N). > > Signed-off-by: Clark Williams > [ paulmck: Ported to rcu/dev, applied Paul Bolle feedback. ] > Signed-off-by: Paul E. McKenney > --- > Documentation/kernel-parameters.txt | 6 ++++++ > init/Kconfig | 23 +++++++++++----------- > kernel/rcu/tree_plugin.h | 20 +++++++++---------- > .../selftests/rcutorture/configs/rcu/TREE03 | 2 +- > .../selftests/rcutorture/doc/TREE_RCU-kconfig.txt | 4 ++-- > 5 files changed, 31 insertions(+), 24 deletions(-) > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > index 7dbe5ec9d9cd..7d3b3328bf5c 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -2922,6 +2922,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted. > quiescent states. Units are jiffies, minimum > value is one, and maximum value is HZ. > > + rcutree.kthread_prio= [KNL,BOOT] > + Set the SCHED_FIFO priority of the RCU > + per-CPU kthreads (rcuc/N). This value is also > + used for the priority of the RCU boost threads > + (rcub/N). Valid values are 1-99. > + It would maybe be useful to mention the default? Also, should we look at running this stuff as deadline in order to provide interference guarantees etc.. ?