Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755578AbaFWP1G (ORCPT ); Mon, 23 Jun 2014 11:27:06 -0400 Received: from e35.co.us.ibm.com ([32.97.110.153]:54703 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754484AbaFWP1D (ORCPT ); Mon, 23 Jun 2014 11:27:03 -0400 Date: Mon, 23 Jun 2014 08:26:56 -0700 From: "Paul E. McKenney" To: Christoph Lameter Cc: Josh Triplett , 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, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, dave.hansen@intel.com, ak@linux.intel.com, umgwanakikbuti@gmail.com Subject: Re: [PATCH tip/core/rcu] Reduce overhead of cond_resched() checks for RCU Message-ID: <20140623152656.GA22225@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20140621025958.GA7185@linux.vnet.ibm.com> <20140621042958.GA4515@thin> <20140621060625.GG4615@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14062315-6688-0000-0000-000002C336F4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 23, 2014 at 08:53:12AM -0500, Christoph Lameter wrote: > On Fri, 20 Jun 2014, Paul E. McKenney wrote: > > > > I like this approach *far* better. This is the kind of thing I had in > > > mind when I suggested using the fqs machinery: remove the poll entirely > > > and just thwack a CPU if it takes too long without a quiescent state. > > > Reviewed-by: Josh Triplett > > > > Glad you like it. Not a fan of the IPI myself, but then again if you > > are spending that must time looping in the kernel, an extra IPI is the > > least of your problems. > > Good. The IPI is only used when actually necessary. The code inserted > was always there and always executed although rarely needed. Interesting. I actually proposed this approach several times in the earlier thread, but to deafing silence: https://lkml.org/lkml/2014/6/18/836, https://lkml.org/lkml/2014/6/17/793, and https://lkml.org/lkml/2014/6/20/479. I guess this further validates interpreting silence as assent. Thanx, Paul -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/