Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933905AbbEMK3C (ORCPT ); Wed, 13 May 2015 06:29:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45073 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933836AbbEMK27 (ORCPT ); Wed, 13 May 2015 06:28:59 -0400 Message-ID: <5553273B.6020405@redhat.com> Date: Wed, 13 May 2015 12:28:11 +0200 From: Denys Vlasenko User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Ingo Molnar CC: Linus Torvalds , Thomas Graf , "David S. Miller" , Bart Van Assche , Peter Zijlstra , David Rientjes , Andrew Morton , Oleg Nesterov , "Paul E. McKenney" , linux-kernel@vger.kernel.org Subject: Re: [PATCH] force inlining of spinlock ops References: <1431367042-31475-1-git-send-email-dvlasenk@redhat.com> <20150512074443.GA724@gmail.com> <5551DDBD.9010803@redhat.com> <20150512114353.GA13699@gmail.com> <5551FC76.40000@redhat.com> <20150513101744.GA4318@gmail.com> In-Reply-To: <20150513101744.GA4318@gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1501 Lines: 39 On 05/13/2015 12:17 PM, Ingo Molnar wrote: >>> In any case, the interesting measurement would not be -Os comparisons >>> (which causes GCC to be too crazy), but to see the size effect of your >>> _patch_ that always-inlines spinlock ops, on plain defconfig and on >>> defconfig-Os. >> >> Here it is: >> >> text data bss dec hex filename >> 12335864 1746152 1081344 15163360 e75fe0 vmlinuxO2.before >> 12335930 1746152 1081344 15163426 e76022 vmlinux > > Hm, that's a (small) size increase on O2. > > That might be a net positive though: because now we've eliminated > quite a few function calls. Do we know which individual functions > bloat and which debloat? >> text data bss dec hex filename >> 10373764 1684200 1077248 13135212 c86d6c vmlinuxOs.before >> 10363621 1684200 1077248 13125069 c845cd vmlinux > > A decrease - which gets exploded on allyesconfig. > > So as long as the -O2 case does not get hurt we can do -Os fixes. > > I think this needs a bit more work to ensure that the O2 case is a net > win. I think O2 difference is just noise: with -O2 gcc is far less prone to bogus deinlining, my patch should have negligible effect. And effect is indeed negligible: +70 bytes on 12 megabytes. -- 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/