From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5AE40C46470 for ; Wed, 8 Aug 2018 11:05:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0261A21737 for ; Wed, 8 Aug 2018 11:05:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=canb.auug.org.au header.i=@canb.auug.org.au header.b="upblgrDM" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0261A21737 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=canb.auug.org.au Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727028AbeHHNYO (ORCPT ); Wed, 8 Aug 2018 09:24:14 -0400 Received: from ozlabs.org ([203.11.71.1]:60241 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726869AbeHHNYO (ORCPT ); Wed, 8 Aug 2018 09:24:14 -0400 Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPSA id 41lpSL6wzWz9ryt; Wed, 8 Aug 2018 21:04:50 +1000 (AEST) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=canb.auug.org.au DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=canb.auug.org.au; s=201702; t=1533726299; bh=DVpGWns8ge1wpKonwTWgPpPLFmArBnFJvOSVZKlYixY=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=upblgrDMab/8oLt+axdv8zXii18uCxhhueYVyCqzJGGrd3tpMv90rjtogkQLNMWUt U8c7NsWxIBPPidavnwC7+VhuxVxoWvrjw/zvIMcNgH87+7gbMMH+ruLm00YRnKZ84V 54RAOvfFz1qk9VL38xCGqqls+oKfG9zIbLYD83aAtwBTibKGoJVbe24TKX8009WEjC vTBQkZUMv0mEKvzhsHcAbS/MFNbX8q7MkGoXg9/OHBAY8phvT+ECSbAtoAS6r4Ftev 14oX/wgmCCD+RRL5ix3GuTWNYQXudpOEsPFMPK5U/R/LxYthNB+/TfcC82xmQ/PBKE cgMoTJQIhTkvg== Date: Wed, 8 Aug 2018 21:04:50 +1000 From: Stephen Rothwell To: Kirill Tkhai Cc: akpm@linux-foundation.org, gregkh@linuxfoundation.org, rafael@kernel.org, viro@zeniv.linux.org.uk, darrick.wong@oracle.com, paulmck@linux.vnet.ibm.com, josh@joshtriplett.org, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, hughd@google.com, shuah@kernel.org, robh@kernel.org, ulf.hansson@linaro.org, aspriel@gmail.com, vivek.gautam@codeaurora.org, robin.murphy@arm.com, joe@perches.com, heikki.krogerus@linux.intel.com, vdavydov.dev@gmail.com, mhocko@suse.com, chris@chris-wilson.co.uk, penguin-kernel@I-love.SAKURA.ne.jp, aryabinin@virtuozzo.com, willy@infradead.org, ying.huang@intel.com, shakeelb@google.com, jbacik@fb.com, mingo@kernel.org, mhiramat@kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH RFC 01/10] rcu: Make CONFIG_SRCU unconditionally enabled Message-ID: <20180808210450.02108372@canb.auug.org.au> In-Reply-To: <9ac119a7-4142-3a5a-6c4b-6f35ad026cb0@virtuozzo.com> References: <153365347929.19074.12509495712735843805.stgit@localhost.localdomain> <153365625652.19074.8434946780002619802.stgit@localhost.localdomain> <20180808110827.65631461@canb.auug.org.au> <9ac119a7-4142-3a5a-6c4b-6f35ad026cb0@virtuozzo.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; boundary="Sig_/NS9RdzWSmlMIFWUxGHf7hWB"; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --Sig_/NS9RdzWSmlMIFWUxGHf7hWB Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Hi Kirill, On Wed, 8 Aug 2018 12:59:40 +0300 Kirill Tkhai wrote: > > On 08.08.2018 04:08, Stephen Rothwell wrote: > >=20 > > So what sort of overheads (in terms of code size and performance) are > > we adding by having SRCU enabled where it used not to be? =20 >=20 > SRCU is unconditionally enabled for x86, so I had to use another arch (sp= arc64) > to check the size difference. The config, I used to compile, is attached,= SRCU > was enabled via: >=20 > diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig > index 2d58c26bff9a..6e9116e356d4 100644 > --- a/arch/sparc/Kconfig > +++ b/arch/sparc/Kconfig > @@ -15,6 +15,7 @@ config SPARC > select ARCH_MIGHT_HAVE_PC_PARPORT if SPARC64 && PCI > select ARCH_MIGHT_HAVE_PC_SERIO > select OF > + select SRCU > select OF_PROMTREE > select HAVE_IDE > select HAVE_OPROFILE >=20 > $ size image.srcu.disabled=20 > text data bss dec hex filename > 5117546 8030506 1968104 15116156 e6a77c image.srcu.disabled >=20 > $ size image.srcu.enabled > text data bss dec hex filename > 5126175 8064346 1968104 15158625 e74d61 image.srcu.enabled >=20 > The difference is: 15158625-15116156 =3D 42469 ~41Kb Thanks for that. > I have not ideas about performance overhead measurements. If you have ide= as, > where they may occur, please say. At the first sight, there should not be > a problem, since SRCU is enabled in x86 by default. I have no idea, just asking questions that might be relevant for platforms where SRCU is normally disabled. --=20 Cheers, Stephen Rothwell --Sig_/NS9RdzWSmlMIFWUxGHf7hWB Content-Type: application/pgp-signature Content-Description: OpenPGP digital signature -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEENIC96giZ81tWdLgKAVBC80lX0GwFAltqzlIACgkQAVBC80lX 0Gxx3Qf7B8JdGdmyDUbzpSrVrCvYft5KUeWIit4wjayC3zqPfE6opmESJwxrGov6 ZfEobR/VNTg8r3HLAXSFgrGo0WUOdEyJwHYd1gfZZVdAevP/LzJMZ6TA8mNVQch8 /XUUGD1B4YL/sR6CNlzCPQnetJhqYxbrDDCbDM9Ek1E+ZnII4Un4or5bY4It4R66 5UaTWGuBK9T5005AkjoNXgb48F0AXA9jkprtxCD44n4hkuzr+1egFLyoonb/ZEoT s73eJN8haDVsK5gZ4CUiKQBwuNZisllJ4+L6tGvEx6pKIVtQqJYrgVLJ5Sbaz6gG qOOuGqBP07jhK/XSWTsL11dWLEe0bg== =YY9L -----END PGP SIGNATURE----- --Sig_/NS9RdzWSmlMIFWUxGHf7hWB--