From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: Re: [PATCH tip/core/rcu 8/9] nohz_full: Add full-system-idle state machine Date: Sat, 7 Sep 2013 11:59:42 -0700 Message-ID: <20130907185942.GG3966@linux.vnet.ibm.com> References: <20130820024700.GA31075@linux.vnet.ibm.com> <1376966841-31774-1-git-send-email-paulmck@linux.vnet.ibm.com> <1376966841-31774-8-git-send-email-paulmck@linux.vnet.ibm.com> <20130906173047.GT3966@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kbuild-owner@vger.kernel.org To: Geert Uytterhoeven Cc: "linux-kernel@vger.kernel.org" , Ingo Molnar , laijs@cn.fujitsu.com, dipankar@in.ibm.com, Andrew Morton , Mathieu Desnoyers , josh@joshtriplett.org, niv@us.ibm.com, Thomas Gleixner , Peter Zijlstra , Steven Rostedt , David Howells , edumazet@google.com, darren@dvhart.com, =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker , Silas Boyd-Wickizer , Linux-Arch , linux-kbuild List-Id: linux-arch.vger.kernel.org On Sat, Sep 07, 2013 at 01:22:57PM +0200, Geert Uytterhoeven wrote: > On Fri, Sep 6, 2013 at 8:50 PM, Geert Uytterhoeven wrote: > > On Fri, Sep 6, 2013 at 7:30 PM, Paul E. McKenney > > wrote: > >>> Furthermore, it seems only hexagon, metag, mips, and x86 set NR_CPUS to 1 > >>> if !SMP. On other architectures, NR_CPUS is not defined and presumed to be 0. > >> > >> Would it make sense to require that NR_CPUS=1 for !SMP? > > > > Yes, this looks reasonable to me. > > Perhaps we can invert the logic and define only NR_CPUS in arch-specific > code, and derive SMP from NR_CPUS != 1 in generic code? If we always had NR_CPUS defined, that might be a good way to go. We would of course need acks from the various arch maintainers. I am guessing that we are OK for m68k. ;-) Thanx, Paul From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e8.ny.us.ibm.com ([32.97.182.138]:57721 "EHLO e8.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751788Ab3IGTAA (ORCPT ); Sat, 7 Sep 2013 15:00:00 -0400 Received: from /spool/local by e8.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Sat, 7 Sep 2013 19:59:59 +0100 Date: Sat, 7 Sep 2013 11:59:42 -0700 From: "Paul E. McKenney" Subject: Re: [PATCH tip/core/rcu 8/9] nohz_full: Add full-system-idle state machine Message-ID: <20130907185942.GG3966@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20130820024700.GA31075@linux.vnet.ibm.com> <1376966841-31774-1-git-send-email-paulmck@linux.vnet.ibm.com> <1376966841-31774-8-git-send-email-paulmck@linux.vnet.ibm.com> <20130906173047.GT3966@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-arch-owner@vger.kernel.org List-ID: To: Geert Uytterhoeven Cc: "linux-kernel@vger.kernel.org" , Ingo Molnar , laijs@cn.fujitsu.com, dipankar@in.ibm.com, Andrew Morton , Mathieu Desnoyers , josh@joshtriplett.org, niv@us.ibm.com, Thomas Gleixner , Peter Zijlstra , Steven Rostedt , David Howells , edumazet@google.com, darren@dvhart.com, =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker , Silas Boyd-Wickizer , Linux-Arch , linux-kbuild Message-ID: <20130907185942.YPyW-tTw3W8kwwhWMFoXSH6BdHdyIP3kVtwkxocoOjs@z> On Sat, Sep 07, 2013 at 01:22:57PM +0200, Geert Uytterhoeven wrote: > On Fri, Sep 6, 2013 at 8:50 PM, Geert Uytterhoeven wrote: > > On Fri, Sep 6, 2013 at 7:30 PM, Paul E. McKenney > > wrote: > >>> Furthermore, it seems only hexagon, metag, mips, and x86 set NR_CPUS to 1 > >>> if !SMP. On other architectures, NR_CPUS is not defined and presumed to be 0. > >> > >> Would it make sense to require that NR_CPUS=1 for !SMP? > > > > Yes, this looks reasonable to me. > > Perhaps we can invert the logic and define only NR_CPUS in arch-specific > code, and derive SMP from NR_CPUS != 1 in generic code? If we always had NR_CPUS defined, that might be a good way to go. We would of course need acks from the various arch maintainers. I am guessing that we are OK for m68k. ;-) Thanx, Paul