From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: Re: [RFC][PATCH 0/5] arch: atomic rework Date: Fri, 7 Feb 2014 08:50:28 -0800 Message-ID: <20140207165028.GO4250@linux.vnet.ibm.com> References: <20140206134825.305510953@infradead.org> <21984.1391711149@warthog.procyon.org.uk> <52F3DA85.1060209@arm.com> <20140206185910.GE27276@mudshark.cambridge.arm.com> <20140206192743.GH4250@linux.vnet.ibm.com> <1391721423.23421.3898.camel@triegel.csb> <20140206221117.GJ4250@linux.vnet.ibm.com> <1391730288.23421.4102.camel@triegel.csb> <20140207042051.GL4250@linux.vnet.ibm.com> <20140207074405.GM5002@laptop.programming.kicks-ass.net> Reply-To: paulmck@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: List-Unsubscribe: List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org Content-Disposition: inline In-Reply-To: <20140207074405.GM5002@laptop.programming.kicks-ass.net> To: Peter Zijlstra Cc: Torvald Riegel , Will Deacon , Ramana Radhakrishnan , David Howells , "linux-arch@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "torvalds@linux-foundation.org" , "akpm@linux-foundation.org" , "mingo@kernel.org" , "gcc@gcc.gnu.org" List-Id: linux-arch.vger.kernel.org On Fri, Feb 07, 2014 at 08:44:05AM +0100, Peter Zijlstra wrote: > On Thu, Feb 06, 2014 at 08:20:51PM -0800, Paul E. McKenney wrote: > > Hopefully some discussion of out-of-thin-air values as well. > > Yes, absolutely shoot store speculation in the head already. Then drive > a wooden stake through its hart. > > C11/C++11 should not be allowed to claim itself a memory model until that > is sorted. There actually is a proposal being put forward, but it might not make ARM and Power people happy because it involves adding a compare, a branch, and an ISB/isync after every relaxed load... Me, I agree with you, much preferring the no-store-speculation approach. Thanx, Paul From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e35.co.us.ibm.com ([32.97.110.153]:42747 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753397AbaBGQuf (ORCPT ); Fri, 7 Feb 2014 11:50:35 -0500 Received: from /spool/local by e35.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 7 Feb 2014 09:50:34 -0700 Date: Fri, 7 Feb 2014 08:50:28 -0800 From: "Paul E. McKenney" Subject: Re: [RFC][PATCH 0/5] arch: atomic rework Message-ID: <20140207165028.GO4250@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20140206134825.305510953@infradead.org> <21984.1391711149@warthog.procyon.org.uk> <52F3DA85.1060209@arm.com> <20140206185910.GE27276@mudshark.cambridge.arm.com> <20140206192743.GH4250@linux.vnet.ibm.com> <1391721423.23421.3898.camel@triegel.csb> <20140206221117.GJ4250@linux.vnet.ibm.com> <1391730288.23421.4102.camel@triegel.csb> <20140207042051.GL4250@linux.vnet.ibm.com> <20140207074405.GM5002@laptop.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140207074405.GM5002@laptop.programming.kicks-ass.net> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Peter Zijlstra Cc: Torvald Riegel , Will Deacon , Ramana Radhakrishnan , David Howells , "linux-arch@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "torvalds@linux-foundation.org" , "akpm@linux-foundation.org" , "mingo@kernel.org" , "gcc@gcc.gnu.org" Message-ID: <20140207165028.tM6zA6DbWvFvJ07qWD3SYWuTAlb3c8ZQhaeyvHAXdcc@z> On Fri, Feb 07, 2014 at 08:44:05AM +0100, Peter Zijlstra wrote: > On Thu, Feb 06, 2014 at 08:20:51PM -0800, Paul E. McKenney wrote: > > Hopefully some discussion of out-of-thin-air values as well. > > Yes, absolutely shoot store speculation in the head already. Then drive > a wooden stake through its hart. > > C11/C++11 should not be allowed to claim itself a memory model until that > is sorted. There actually is a proposal being put forward, but it might not make ARM and Power people happy because it involves adding a compare, a branch, and an ISB/isync after every relaxed load... Me, I agree with you, much preferring the no-store-speculation approach. Thanx, Paul