From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e35.co.us.ibm.com (e35.co.us.ibm.com [32.97.110.153]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 019B01A04C0 for ; Thu, 1 Jan 2015 00:19:39 +1100 (AEDT) Received: from /spool/local by e35.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 31 Dec 2014 06:19:38 -0700 Received: from b03cxnp08026.gho.boulder.ibm.com (b03cxnp08026.gho.boulder.ibm.com [9.17.130.18]) by d03dlp01.boulder.ibm.com (Postfix) with ESMTP id E740A1FF001A for ; Wed, 31 Dec 2014 06:08:19 -0700 (MST) Received: from d03av01.boulder.ibm.com (d03av01.boulder.ibm.com [9.17.195.167]) by b03cxnp08026.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id sBVDK91K48103612 for ; Wed, 31 Dec 2014 06:20:09 -0700 Received: from d03av01.boulder.ibm.com (localhost [127.0.0.1]) by d03av01.boulder.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id sBVDJWEG016563 for ; Wed, 31 Dec 2014 06:19:35 -0700 Date: Wed, 31 Dec 2014 05:19:30 -0800 From: "Paul E. McKenney" To: Peter Zijlstra Subject: Re: [PATCH v2] srcu: Isolate srcu sections using CONFIG_SRCU Message-ID: <20141231131930.GQ11609@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <1419918382-4758-1-git-send-email-bobby.prani@gmail.com> <1419918382-4758-2-git-send-email-bobby.prani@gmail.com> <20141230185008.GA23965@worktop.programming.kicks-ass.net> <20141230190740.GC23965@worktop.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20141230190740.GC23965@worktop.programming.kicks-ass.net> Cc: Heiko Carstens , Tiejun Chen , Paul Mackerras , Daniel Walter , Ingo Molnar , "open list:S390" , Vincent Guittot , Christian Borntraeger , Jens Freimann , Pranith Kumar , Josh Triplett , Steven Rostedt , Mathieu Desnoyers , Anton Blanchard , Scott Wood , Lai Jiangshan , Li Zhong , Nishanth Aravamudan , open list , "Srivatsa S. Bhat" , Martin Schwidefsky , "supporter:S390" , "open list:LINUX FOR POWERPC..." List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, Dec 30, 2014 at 08:07:40PM +0100, Peter Zijlstra wrote: > On Tue, Dec 30, 2014 at 01:54:07PM -0500, Pranith Kumar wrote: > > On Tue, Dec 30, 2014 at 1:50 PM, Peter Zijlstra wrote: > > > On Tue, Dec 30, 2014 at 12:46:22AM -0500, Pranith Kumar wrote: > > >> Isolate the SRCU functions and data structures within CONFIG_SRCU so that there > > >> is a compile time failure if srcu is used when not enabled. This was decided to > > >> be better than waiting until link time for a failure to occur. > > > > > > Why? > > > > This is part of the kernel tinification efforts. The first patch was > > posted here: https://lkml.org/lkml/2014/12/4/848. This patch enables a > > compile time failure instead of a link time failure. > > can't be arsed to click. again, why does it matter when it fails, > neither stages produces a working kernel so tinification cannot be the > purpose. In fairness, Pranith's original submission did force the failure at link time. One piece of feedback was to force the failure at compile time (can't remember from who). But given the hassles encountered with compile-time failure, it might well be getting to the point where it is time to fall back to the link-time-failure approach. Thanx, Paul