Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934715AbaFSVNQ (ORCPT ); Thu, 19 Jun 2014 17:13:16 -0400 Received: from qmta06.emeryville.ca.mail.comcast.net ([76.96.30.56]:50768 "EHLO qmta06.emeryville.ca.mail.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934620AbaFSVNP (ORCPT ); Thu, 19 Jun 2014 17:13:15 -0400 Date: Thu, 19 Jun 2014 16:13:12 -0500 (CDT) From: Christoph Lameter To: "Paul E. McKenney" cc: Andi Kleen , Dave Hansen , LKML , Josh Triplett , "Chen, Tim C" Subject: Re: [bisected] pre-3.16 regression on open() scalability In-Reply-To: <20140619204220.GJ4904@linux.vnet.ibm.com> Message-ID: References: <20140618001836.GV4669@linux.vnet.ibm.com> <53A132D4.60408@intel.com> <20140618125831.GB4669@linux.vnet.ibm.com> <53A1CE19.7040103@intel.com> <20140618203052.GT4669@linux.vnet.ibm.com> <20140618235131.GA25946@linux.vnet.ibm.com> <20140619014200.GO8178@tassilo.jf.intel.com> <20140619180916.GE4904@linux.vnet.ibm.com> <20140619204220.GJ4904@linux.vnet.ibm.com> Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 19 Jun 2014, Paul E. McKenney wrote: > On Thu, Jun 19, 2014 at 03:31:56PM -0500, Christoph Lameter wrote: > > On Thu, 19 Jun 2014, Paul E. McKenney wrote: > > > > > That is a separate issue, but unnecessary calls to cond_resched() > > > should of course be removed -- no argument there. > > > > It looks like we are fighting higher latencies by adding calls in most of > > the critical sections which will in turn increase the latencies that we > > are trying to reduce. > > That is on battle in a larger war. Another battle is to keep big systems > from choking and dying. We need to win both battles, though I understand > that you are focused primarily on latency reduction. I don't get that > luxury because RCU is used across the board. At least reduce the increased latencies to a processor or put it somewhere outside of the regular execution paths. Sprinkling this throughout the kernel via a inline function that did not generate code in the non debug situation before is not that nice. -- 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/