Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932900AbaFSOmW (ORCPT ); Thu, 19 Jun 2014 10:42:22 -0400 Received: from qmta15.emeryville.ca.mail.comcast.net ([76.96.27.228]:50372 "EHLO qmta15.emeryville.ca.mail.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756624AbaFSOmV (ORCPT ); Thu, 19 Jun 2014 10:42:21 -0400 Date: Thu, 19 Jun 2014 09:42:18 -0500 (CDT) From: Christoph Lameter To: Andi Kleen cc: "Paul E. McKenney" , Dave Hansen , LKML , Josh Triplett , "Chen, Tim C" Subject: Re: [bisected] pre-3.16 regression on open() scalability In-Reply-To: <20140619014200.GO8178@tassilo.jf.intel.com> Message-ID: References: <539B594C.8070004@intel.com> <20140613224519.GV4581@linux.vnet.ibm.com> <53A0CAE5.9000702@intel.com> <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> 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 Wed, 18 Jun 2014, Andi Kleen wrote: > I still think it's totally the wrong direction to pollute so > many fast paths with this obscure debugging check workaround > unconditionally. > > cond_resched() is in EVERY sleeping lock and in EVERY memory allocation! > And these are really critical paths for many workloads. > > If you really wanted to do this I think you would first need > to define a cond_resched_i_am_not_fast() or somesuch. > > Or put it all behind some debugging ifdef. Again I am fully on Andi's side here. Please remove these frequent calls to cond_resched. If one wants a fully preemptable kernel then please use CONFIG_PREEMPT. -- 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/