From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755933AbcETPBF (ORCPT ); Fri, 20 May 2016 11:01:05 -0400 Received: from mx2.suse.de ([195.135.220.15]:47346 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755349AbcETPBD (ORCPT ); Fri, 20 May 2016 11:01:03 -0400 Date: Fri, 20 May 2016 08:00:49 -0700 From: Davidlohr Bueso To: Peter Zijlstra Cc: manfred@colorfullife.com, Waiman.Long@hpe.com, mingo@kernel.org, torvalds@linux-foundation.org, ggherdovich@suse.com, mgorman@techsingularity.net, linux-kernel@vger.kernel.org Subject: Re: sem_lock() vs qspinlocks Message-ID: <20160520150049.GB7086@linux-uzut.site> References: <20160520053926.GC31084@linux-uzut.site> <20160520074946.GA3193@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20160520074946.GA3193@twins.programming.kicks-ass.net> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 20 May 2016, Peter Zijlstra wrote: >On Thu, May 19, 2016 at 10:39:26PM -0700, Davidlohr Bueso wrote: >> In addition, this makes me wonder if queued_spin_is_locked() should then be: >> >> - return atomic_read(&lock->val); >> + return atomic_read(&lock->val) & _Q_LOCKED_MASK; >> >> And avoid considering pending waiters as locked. > >Probably Similarly, and I know you hate it, but afaict, then semantically queued_spin_is_contended() ought to be: - return atomic_read(&lock->val) & ~_Q_LOCKED_MASK; + return atomic_read(&lock->val); Thanks, Davidlohr