From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754238AbbGAORb (ORCPT ); Wed, 1 Jul 2015 10:17:31 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:56519 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752103AbbGAORY (ORCPT ); Wed, 1 Jul 2015 10:17:24 -0400 Date: Wed, 1 Jul 2015 16:17:10 +0200 From: Peter Zijlstra To: "Paul E. McKenney" Cc: josh@joshtriplett.org, 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: <20150701141710.GG25159@twins.programming.kicks-ass.net> References: <20150630214805.GA7795@linux.vnet.ibm.com> <20150630220014.GA10916@cloud> <20150630221224.GQ3717@linux.vnet.ibm.com> <20150630234633.GA11450@cloud> <20150701100939.GR19282@twins.programming.kicks-ass.net> <20150701105511.GN18673@twins.programming.kicks-ass.net> <20150701140031.GB3717@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150701140031.GB3717@linux.vnet.ibm.com> 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 Wed, Jul 01, 2015 at 07:00:31AM -0700, Paul E. McKenney wrote: > That is a bit extreme, Peter. Of course; but I'm really not seeing people taking due care with them > Are a huge pile of them coming in this merge window or something? > What raised your concerns on this issue? This is complete horse manure (breaking the nvidiot binary blob is a good thing): 74b51ee152b6 ("ACPI / osl: speedup grace period in acpi_os_map_cleanup") Also, I'm not entirely convinced things like: fd2ed4d25270 ("dm: add statistics support") 83d5e5b0af90 ("dm: optimize use SRCU and RCU") ef3230880abd ("backing-dev: use synchronize_rcu_expedited instead of synchronize_rcu") Are in the 'never' happens category. Esp. the backing-dev one, it triggers every time you unplug a USB stick or similar. Rejigging a DM might indeed be rare enough; but then again, people use DM explicitly so they can rejig while in operation. Also, they really do not explain how expedited really is the only option available. Why things can't be batched etc..