Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755124AbaGKTFO (ORCPT ); Fri, 11 Jul 2014 15:05:14 -0400 Received: from qmta02.emeryville.ca.mail.comcast.net ([76.96.30.24]:53868 "EHLO qmta02.emeryville.ca.mail.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751441AbaGKTFM (ORCPT ); Fri, 11 Jul 2014 15:05:12 -0400 Date: Fri, 11 Jul 2014 14:05:08 -0500 (CDT) From: Christoph Lameter To: Frederic Weisbecker cc: "Paul E. McKenney" , 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, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, oleg@redhat.com, sbw@mit.edu Subject: Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs In-Reply-To: <20140711182541.GF26045@localhost.localdomain> Message-ID: References: <20140707223756.GA7187@linux.vnet.ibm.com> <1404772701-8804-1-git-send-email-paulmck@linux.vnet.ibm.com> <1404772701-8804-11-git-send-email-paulmck@linux.vnet.ibm.com> <20140708152358.GF6571@localhost.localdomain> <20140708154723.GN4603@linux.vnet.ibm.com> <20140708183846.GJ6571@localhost.localdomain> <20140711182541.GF26045@localhost.localdomain> 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, 11 Jul 2014, Frederic Weisbecker wrote: > > That would imply that all no-nohz processors are housekeeping? So all > > processors with a tick are housekeeping? > > Well, now that I think about it again, I would really like to keep housekeeping > to CPU 0 when nohz_full= is passed. Yeah. > > Could we make that set configurable? Ideally I'd like to have the ability > > restrict the housekeeping to one processor. > > Ah, I'm curious about your usecase. But I think we can do that. And we should. The use case is pretty straightforward because we are trying to keep as much OS noise as possible off most processors. Processor 0 is the sacrificial lamb that will be used for all OS processing and hopefully all high latency operations will occur there. Processors 1-X have a tick but we still try to keep latencies sane. And then there is X-Y where tick is off. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/