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=-2.3 required=3.0 tests=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 CCFA1C04ABB for ; Tue, 11 Sep 2018 19:21:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 71BCE20839 for ; Tue, 11 Sep 2018 19:21:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 71BCE20839 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=stgolabs.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727007AbeILAWP (ORCPT ); Tue, 11 Sep 2018 20:22:15 -0400 Received: from mx2.suse.de ([195.135.220.15]:41324 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726713AbeILAWP (ORCPT ); Tue, 11 Sep 2018 20:22:15 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 8BB5AAE04; Tue, 11 Sep 2018 19:21:30 +0000 (UTC) Date: Tue, 11 Sep 2018 12:21:22 -0700 From: Davidlohr Bueso To: Peter Zijlstra Cc: Waiman Long , Ingo Molnar , Will Deacon , linux-kernel@vger.kernel.org Subject: Re: [PATCH] locking/rwsem: Make owner store task pointer of last owning reader Message-ID: <20180911192122.GD3902@linux-r8p5> References: <1536265114-10842-1-git-send-email-longman@redhat.com> <20180910093156.GS24082@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20180910093156.GS24082@hirez.programming.kicks-ass.net> 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 Mon, 10 Sep 2018, Peter Zijlstra wrote: >[ RT has something along those lines, and I have half a patch that > starts doing that too, but I never found enough time to really work on > it :-( ] But don't rt rwsems act pretty much like a regular mutex in that it only allows readers to nest, not share the lock because of priority inversion scenarios. Also, wrt rtmutex, will that top-spinner thing ever make it in? Thanks, Davidlohr