From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753487AbbGAKKB (ORCPT ); Wed, 1 Jul 2015 06:10:01 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:52003 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750768AbbGAKJy (ORCPT ); Wed, 1 Jul 2015 06:09:54 -0400 Date: Wed, 1 Jul 2015 12:09:39 +0200 From: Peter Zijlstra To: josh@joshtriplett.org 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, tglx@linutronix.de, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com Subject: Re: [PATCH RFC tip/core/rcu 0/5] Expedited grace periods encouraging normal ones Message-ID: <20150701100939.GR19282@twins.programming.kicks-ass.net> References: <20150630214805.GA7795@linux.vnet.ibm.com> <20150630220014.GA10916@cloud> <20150630221224.GQ3717@linux.vnet.ibm.com> <20150630234633.GA11450@cloud> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150630234633.GA11450@cloud> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 30, 2015 at 04:46:33PM -0700, josh@joshtriplett.org wrote: > Consider it a fairly weak concern against. Increasing performance seems > like a good thing in general; I just don't relish the future "feels less > responsive" bug reports that take a long time to track down and turn out > to be "this completely unrelated driver was loaded and started using > expedited grace periods". random drivers, or for that matter, new-code of any sort. Should _NOT_ be using expedited grace periods. They're a horrid hack only suitable for unfixable ABI. > Then again, perhaps the more relevant concern would be why drivers use > expedited grace periods in the first place. Right.