From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751472AbeBWLiv (ORCPT ); Fri, 23 Feb 2018 06:38:51 -0500 Received: from merlin.infradead.org ([205.233.59.134]:33928 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750935AbeBWLiu (ORCPT ); Fri, 23 Feb 2018 06:38:50 -0500 Date: Fri, 23 Feb 2018 12:38:43 +0100 From: Peter Zijlstra To: Boqun Feng Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Andrea Parri Subject: Re: [RFC tip/locking/lockdep v5 15/17] lockdep: Reduce the size of lock_list Message-ID: <20180223113843.GY25201@hirez.programming.kicks-ass.net> References: <20180222070904.548-1-boqun.feng@gmail.com> <20180222070904.548-16-boqun.feng@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180222070904.548-16-boqun.feng@gmail.com> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 22, 2018 at 03:09:02PM +0800, Boqun Feng wrote: > diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h > index a1f91f8680bd..3fce8dbf5091 100644 > --- a/include/linux/lockdep.h > +++ b/include/linux/lockdep.h > @@ -186,11 +186,11 @@ struct lock_list { > struct list_head entry; > struct lock_class *class; > struct stack_trace trace; > - int distance; > + u16 distance; > /* bitmap of different dependencies from head to this */ > - u16 dep; > + u8 dep; > /* used by BFS to record whether this is picked as a recursive read */ > - u16 is_rr; > + bool is_rr; Don't use bool, use u8 if you want a single byte. sizeof(_Bool) is part of the architecture ABI and can be up to 4 bytes (well really anything, but I've not seen it bigger than 4 bytes for any sane implementation).