Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965666AbaFSVcK (ORCPT ); Thu, 19 Jun 2014 17:32:10 -0400 Received: from relay4-d.mail.gandi.net ([217.70.183.196]:49572 "EHLO relay4-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964833AbaFSVcI (ORCPT ); Thu, 19 Jun 2014 17:32:08 -0400 Date: Thu, 19 Jun 2014 14:32:03 -0700 From: josh@joshtriplett.org To: Christoph Lameter Cc: "Paul E. McKenney" , Andi Kleen , Dave Hansen , LKML , "Chen, Tim C" Subject: Re: [bisected] pre-3.16 regression on open() scalability Message-ID: <20140619213203.GA16747@cloud> References: <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 19, 2014 at 04:16:34PM -0500, Christoph Lameter wrote: > This looks very much like the CONFIG_PREEMPT problem in not so > extreme form. Maybe we need to add another config option: > > CONFIG_REALLY_REALLY_NO_PREEMPT > > to get the fastest code possible and those cond_rescheds removed from the > critical paths? > > Or better > > CONFIG_PREEMPT_HALF_WAY > > to enable those cond_rescheds. That much actually does seem quite reasonable: making cond_resched() do non-trivial work ought to have a config option to disable it. -- 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/