Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754364Ab3GAQTN (ORCPT ); Mon, 1 Jul 2013 12:19:13 -0400 Received: from one.firstfloor.org ([193.170.194.197]:56297 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752039Ab3GAQTM (ORCPT ); Mon, 1 Jul 2013 12:19:12 -0400 Date: Mon, 1 Jul 2013 18:19:10 +0200 From: Andi Kleen To: "Paul E. McKenney" Cc: Andi Kleen , linux-kernel@vger.kernel.org, mingo@elte.hu, 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, darren@dvhart.com, fweisbec@gmail.com, sbw@mit.edu Subject: Re: [PATCH RFC nohz_full 0/7] v2 Provide infrastructure for full-system idle Message-ID: <20130701161910.GN6123@two.firstfloor.org> References: <20130628200949.GA17458@linux.vnet.ibm.com> <87a9m65mv6.fsf@tassilo.jf.intel.com> <20130701160314.GM3773@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130701160314.GM3773@linux.vnet.ibm.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1037 Lines: 27 > I am guessing that you want CONFIG_NO_HZ_FULL to implicitly enable > the sysidle code so that CONFIG_NO_HZ_FULL_SYSIDLE can be eliminated. > I will be happy to take that step, but only after I gain full confidence > in the correctness and performance of the sysidle code. FWIW if you want useful testing you need to enable it by default (as part of NO_IDLE_HZ) anyways. Users will most likely pick whatever is "default" in Kconfig. > > If you want a switch for testing I would advise a sysctl or sysfs knob > > This would work well for the correctness part, but not for the performance > part. What performance part? Are you saying this adds so many checks to hot paths that normal runtime if() with a flag is too expensive? -Andi -- ak@linux.intel.com -- Speaking for myself only. -- 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/