From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753550AbcFOTcH (ORCPT ); Wed, 15 Jun 2016 15:32:07 -0400 Received: from mail-bn1bon0135.outbound.protection.outlook.com ([157.56.111.135]:29856 "EHLO na01-bn1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751867AbcFOTcC (ORCPT ); Wed, 15 Jun 2016 15:32:02 -0400 X-Greylist: delayed 1264 seconds by postgrey-1.27 at vger.kernel.org; Wed, 15 Jun 2016 15:32:02 EDT Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=waiman.long@hpe.com; Message-ID: <5761AD27.9020106@hpe.com> Date: Wed, 15 Jun 2016 15:31:51 -0400 From: Waiman Long User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.12) Gecko/20130109 Thunderbird/10.0.12 MIME-Version: 1.0 To: Peter Zijlstra CC: Ingo Molnar , , , , , , , Davidlohr Bueso , Jason Low , Dave Chinner , Scott J Norton , Douglas Hatch Subject: Re: [RFC PATCH-tip v2 5/6] locking/rwsem: Change RWSEM_WAITING_BIAS for better disambiguation References: <1465944489-43440-1-git-send-email-Waiman.Long@hpe.com> <1465944489-43440-6-git-send-email-Waiman.Long@hpe.com> <20160615174348.GT30921@twins.programming.kicks-ass.net> In-Reply-To: <20160615174348.GT30921@twins.programming.kicks-ass.net> Content-Type: text/plain; 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To hit the limit, we need to have all the threads calling down_write() at exactly the same instance in time which, I think, is pretty hard to do. Also, I don't believe you will ever see a 16k-cpu massive SMP system running on 32-bit kernel. I can imagine such a system running on 64-bit kernel, but certainly not 32-bit. Cheers, Longman