Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965273AbaFSUoy (ORCPT ); Thu, 19 Jun 2014 16:44:54 -0400 Received: from e38.co.us.ibm.com ([32.97.110.159]:51801 "EHLO e38.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964975AbaFSUow (ORCPT ); Thu, 19 Jun 2014 16:44:52 -0400 Date: Thu, 19 Jun 2014 13:42:20 -0700 From: "Paul E. McKenney" To: Christoph Lameter Cc: Andi Kleen , Dave Hansen , LKML , Josh Triplett , "Chen, Tim C" Subject: Re: [bisected] pre-3.16 regression on open() scalability Message-ID: <20140619204220.GJ4904@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com 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> 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: 14061920-1344-0000-0000-0000024F25F1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. 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/