From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0FBC8C04A6B for ; Mon, 6 May 2019 11:49:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D493420675 for ; Mon, 6 May 2019 11:49:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="kKO7IttU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726270AbfEFLtu (ORCPT ); Mon, 6 May 2019 07:49:50 -0400 Received: from merlin.infradead.org ([205.233.59.134]:53698 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725852AbfEFLtu (ORCPT ); Mon, 6 May 2019 07:49:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=8UHyDT2NILIE6zelkrFD5LEf4niBe1di0tdn/KNzg4M=; b=kKO7IttUgrME5GjDQi9dLpeY2 1r8+8i08arpw2i1fcGbhzB1S1Gxyuq02QfioPqX6OJTuaMmK6q+YMOWtSAahAhKasiCQq1p+SwDDd qaSyuIql0NxgPJxpWg6OUevUUMXH1OU1OCtty49lC2KlJ8SW34C6fxIdSc7ubma0avVw/aIfL5/dE X3fEQc8sN3m+FvbHaT3Ci8vzJo945BTKPhwXVq6yjVHhhH5mUIEdphVJRYsqLBMBH17SZE3hP0QhU cVJMStSZxbnChc/zjaGwDHcm1DSxd/ToDF5zPcA//rlvHM8urbCq9MMbcvGXICDraWAMgPrrcked3 KjfvqJxog==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hNc7e-00012T-Nd; Mon, 06 May 2019 11:49:30 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 046F3286B6532; Mon, 6 May 2019 13:49:27 +0200 (CEST) Date: Mon, 6 May 2019 13:49:27 +0200 From: Peter Zijlstra To: Waiman Long Cc: Ingo Molnar , Will Deacon , Thomas Gleixner , Borislav Petkov , "H. Peter Anvin" , linux-kernel@vger.kernel.org, x86@kernel.org, Davidlohr Bueso , Linus Torvalds , Tim Chen , huang ying Subject: Re: [PATCH-tip v7 11/20] locking/rwsem: Wake up almost all readers in wait queue Message-ID: <20190506114927.GJ2623@hirez.programming.kicks-ass.net> References: <20190428212557.13482-1-longman@redhat.com> <20190428212557.13482-12-longman@redhat.com> <20190503165141.GI2623@hirez.programming.kicks-ass.net> <1e5e939f-3725-14d9-feec-aabb63998406@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1e5e939f-3725-14d9-feec-aabb63998406@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 03, 2019 at 01:15:22PM -0400, Waiman Long wrote: > Yes, that can work. However, that will require adding one more pointer > to the rw_semaphore structure. The performance gain with this > optimization may not justify increasing the size of the structure by 4/8 > bytes. Indeed; what was I thinking :-)