Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755261AbaAUSn3 (ORCPT ); Tue, 21 Jan 2014 13:43:29 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37557 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754934AbaAUSn0 (ORCPT ); Tue, 21 Jan 2014 13:43:26 -0500 Date: Tue, 21 Jan 2014 19:43:10 +0100 From: Oleg Nesterov To: Dave Jones , Peter Zijlstra , Alan Stern , Greg Kroah-Hartman , Ingo Molnar , Linus Torvalds , Paul McKenney , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org Subject: Re: [PATCH 5/5] lockdep: pack subclass/trylock/read/check into a single argument Message-ID: <20140121184310.GA24702@redhat.com> References: <20140120181942.GA20783@redhat.com> <20140120182019.GA26515@redhat.com> <20140121141022.GX31570@twins.programming.kicks-ass.net> <20140121173534.GA25642@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140121173534.GA25642@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/21, Dave Jones wrote: > > On Tue, Jan 21, 2014 at 03:10:22PM +0100, Peter Zijlstra wrote: > > > > I tried the below but filed to see my vmlinux shrink, maybe I'm just not > > building the right kernel, or otherwise GCC is stupid. > > > > -extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass, > > - int trylock, int read, int check, > > - struct lockdep_map *nest_lock, unsigned long ip); > > +struct lockdep_acquire_flags { > > + unsigned long subclass : 3; > > + unsigned long trylock : 1; > > + unsigned long read : 2; > > + unsigned long check : 1; > > +}; > > As it's only 7 bits here, could we pack them into a char ? Do you mean __attribute__((packed)) ? Suprizingly it helps a bit. Still "size vmlinux" is worse than with bitmasks. But I agreed that the code looks simpler with bitfields, so perhaps this patch is better. Oleg. -- 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/