Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757147AbaFSCuY (ORCPT ); Wed, 18 Jun 2014 22:50:24 -0400 Received: from mail-we0-f169.google.com ([74.125.82.169]:52464 "EHLO mail-we0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754662AbaFSCuX (ORCPT ); Wed, 18 Jun 2014 22:50:23 -0400 Message-ID: <1403146219.5189.4.camel@marge.simpson.net> Subject: Re: [bisected] pre-3.16 regression on open() scalability From: Mike Galbraith To: paulmck@linux.vnet.ibm.com Cc: Andi Kleen , Dave Hansen , LKML , Josh Triplett , "Chen, Tim C" , Christoph Lameter Date: Thu, 19 Jun 2014 04:50:19 +0200 In-Reply-To: <20140619021337.GA4669@linux.vnet.ibm.com> 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> <20140619021337.GA4669@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2014-06-18 at 19:13 -0700, Paul E. McKenney wrote: > On Wed, Jun 18, 2014 at 06:42:00PM -0700, 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. > > OOM prevention should count for something, I would hope. > > > 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. > > My first thought was to put it behind CONFIG_NO_HZ_FULL, but everyone > seems to be enabling that one. Not everybody, SUSE doesn't even have it enabled in factory. -Mike -- 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/