Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757560AbaGCHcB (ORCPT ); Thu, 3 Jul 2014 03:32:01 -0400 Received: from casper.infradead.org ([85.118.1.10]:36267 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755547AbaGCHb7 (ORCPT ); Thu, 3 Jul 2014 03:31:59 -0400 Date: Thu, 3 Jul 2014 09:31:48 +0200 From: Peter Zijlstra To: Jason Low Cc: torvalds@linux-foundation.org, paulmck@linux.vnet.ibm.com, mingo@kernel.org, Waiman.Long@hp.com, davidlohr@hp.com, linux-kernel@vger.kernel.org, riel@redhat.com, akpm@linux-foundation.org, hpa@zytor.com, andi@firstfloor.org, James.Bottomley@hansenpartnership.com, rostedt@goodmis.org, tim.c.chen@linux.intel.com, aswin@hp.com, scott.norton@hp.com, chegu_vinod@hp.com Subject: Re: [RFC] Cancellable MCS spinlock rework Message-ID: <20140703073148.GT19379@twins.programming.kicks-ass.net> References: <1404318070-2856-1-git-send-email-jason.low2@hp.com> <20140702162749.GP19379@twins.programming.kicks-ass.net> <1404320356.3170.12.camel@j-VirtualBox> <20140702172333.GQ19379@twins.programming.kicks-ass.net> <1404322203.3170.17.camel@j-VirtualBox> <1404362358.8764.6.camel@j-VirtualBox> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="a+0P3INHs7aeI7wh" Content-Disposition: inline In-Reply-To: <1404362358.8764.6.camel@j-VirtualBox> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --a+0P3INHs7aeI7wh Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jul 02, 2014 at 09:39:18PM -0700, Jason Low wrote: > And due to padding, the additional modification below reduces the > size of struct rw_semaphore by 64 bits on my machine :) >=20 >=20 > struct rw_semaphore { > long count; > - raw_spinlock_t wait_lock; > struct list_head wait_list; > + raw_spinlock_t wait_lock; > #ifdef CONFIG_SMP > + struct optimistic_spin_tail osq; /* spinner MCS lock */ > /* > * Write owner. Used as a speculative check to see > * if the owner is running on the cpu. > */ > struct task_struct *owner; > - struct optimistic_spin_tail osq; /* spinner MCS lock */ > #endif > #ifdef CONFIG_DEBUG_LOCK_ALLOC > struct lockdep_map dep_map; >=20 Right, that might make sense. --a+0P3INHs7aeI7wh Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJTtQbkAAoJEHZH4aRLwOS6qs4P/i7JeWnipGu4SMYsMH00LW/a EPpgosbOfiEXLvmPTABKjSlXFcr6/RQzvA8P+/3PCiDx9luqpHirlbPOGjKH30pe 0MRIv1M5aVOJkdMcUFO+G1ZETTPn6odhl/qS/RuH0+R/Uf7NujbYaSgjlLgfR1R9 vMLUVzHBI4/ubOB/UHYkpJV8rLEMrjmqd2wnDj41EFF8h66LhQkJmRp40aL8SZ3g UvLEcYDLGWZc5pC/84BV8NAZbmadJC/lC1gAID/4G7a2O8rQrD0ZEfHYTB4e0j0O n5KGJizJD9KlTdoQw5MdXqtHrA+kzTgllAEH3N46dmimfDWgcLrxlADkeBKBdhwZ okG3GAoatVqsdROJmH/7/HzJGgtOKCqpm/x7LS+vKebli+jxcyzMclqgfrtVypVR xhnkv0aM2KsThb4T+ayStXxcnADWRW9eDCDbMYMCFtDOtqGC059WACcosJV0kxiV qpPlxzU4K2PPqTG6WiUfIfgW+cWHVD56XBIlz+XuqiSeykWdmgfL2REOb43UFXjF Z7aEPuXdgjZY45ekBXEalOU4vUyOGLvxLjj3WeDMW0pWkW6aYjEG+u/WoIoIv1FG 3VXcY/XF2XoCBtI6fF/+/VneMSoxwjieQ3JhMcdT/CRTLg08eIhfjwZyCsa/SktT Th+8IBsE1VJycrzBt0ov =EUv8 -----END PGP SIGNATURE----- --a+0P3INHs7aeI7wh-- -- 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/