Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751654AbaFETWO (ORCPT ); Thu, 5 Jun 2014 15:22:14 -0400 Received: from g6t1526.atlanta.hp.com ([15.193.200.69]:49668 "EHLO g6t1526.atlanta.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751914AbaFETWN (ORCPT ); Thu, 5 Jun 2014 15:22:13 -0400 Message-ID: <1401996117.6680.33.camel@j-VirtualBox> Subject: Re: [RFC PATCH 1/3] locking/mutex: Try to acquire mutex only if it is unlocked From: Jason Low To: Waiman Long Cc: Peter Zijlstra , mingo@kernel.org, tglx@linutronix.de, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, paulmck@linux.vnet.ibm.com, tim.c.chen@linux.intel.com, peter@hurleysoftware.com, riel@redhat.com, hpa@zytor.com, walken@google.com, davidlohr@hp.com, aswin@hp.com, scott.norton@hp.com, chegu_vinod@hp.com Date: Thu, 05 Jun 2014 12:21:57 -0700 In-Reply-To: <538FE2DE.8080800@hp.com> References: <1401908911-8947-1-git-send-email-jason.low2@hp.com> <1401908911-8947-2-git-send-email-jason.low2@hp.com> <20140604194322.GN13930@laptop.programming.kicks-ass.net> <1401917173.2232.14.camel@j-VirtualBox> <538FE2DE.8080800@hp.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2014-06-04 at 23:24 -0400, Waiman Long wrote: > On 06/04/2014 05:26 PM, Jason Low wrote: > > On Wed, 2014-06-04 at 21:43 +0200, Peter Zijlstra wrote: > >> Please make them inline functions, also can we rename the SHOW_NO_WAITER > >> thing, because its not at all clear to me wtf it does; should it be > >> called: mutex_no_waiters() or somesuch? > > Okay, I can make them inline functions. I mainly added the macro to keep > > it consistent with the MUTEX_SHOW_NO_WAITER() check, but we can surely > > make this more clear. mutex_no_waiters() sounds fine, or perhaps > > something like mutex_has_no_waiters()? > > > > You can remove the MUTEX_SHOW_NO_WAITER macro as all the call sites are > to be replaced. Sure. > I didn't check directly for unlocked count because of > fairness concern in my original patch, but I think checking directly for > unlocked count should be fine too. Can you elaborate on the "fairness concern"? In the current code, we're already directly checking for unlocked count in atomic_read(&lock->count) == 1 if that's what you're referring to. Thanks, Jason -- 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/