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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT 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 2F4BBECDE47 for ; Thu, 8 Nov 2018 17:00:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F3AB920825 for ; Thu, 8 Nov 2018 17:00:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F3AB920825 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=atomide.com 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 S1726995AbeKICgZ (ORCPT ); Thu, 8 Nov 2018 21:36:25 -0500 Received: from muru.com ([72.249.23.125]:53540 "EHLO muru.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726585AbeKICgZ (ORCPT ); Thu, 8 Nov 2018 21:36:25 -0500 Received: from atomide.com (localhost [127.0.0.1]) by muru.com (Postfix) with ESMTPS id 11792812D; Thu, 8 Nov 2018 17:00:00 +0000 (UTC) Date: Thu, 8 Nov 2018 08:59:58 -0800 From: Tony Lindgren To: Lukasz Luba Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, b.zolnierkie@samsung.com, linux-omap@vger.kernel.org Subject: Re: [PATCH] config: arm: omap2: remove PROVE_LOCKING from defconfig Message-ID: <20181108165958.GK56134@atomide.com> References: <20181009153624eucas1p2ad30aea33ad1c869f11bd9ca1156d9af~b_rxQW8J90311703117eucas1p2U@eucas1p2.samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181009153624eucas1p2ad30aea33ad1c869f11bd9ca1156d9af~b_rxQW8J90311703117eucas1p2U@eucas1p2.samsung.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, * Lukasz Luba [181009 08:36]: > PROVE_LOCKING enables LOCKDEP, which causes big overhead on cache and > bus transactions. > > On some ARM big.LITTLE architecutres (Exynos 5433) the overhead is really big. > The overhead can be measures using hackbench which will speed up > by x3 times (11sec -> 3.4sec). > When you check transaction on cache or buses, the results are way higher > than normal for the same hackbench test: > L1d cache invalidations: 26mln vs 4mln > L2u cache invalidations: 42mln vs 12mln > bus cyc/access: 30cyc/access vs. 20cyc/access > context switch is x3 times cheaper > > Enable this option only when you have some locking issue to investigate. I'm all for this, but this disables also other less intrusive debug options. It used to be that we'd get locking issues merged into drivers and I think that's how it originally got enabled. So we should take a look which ones we can or want to keep. Or just disable CONFIG_DEBUG completely. For distros, that's multi_v7_defconfig nowadays for most part so I think most people using omap2plus_defconfig are developers working on various devices. Regards, Tony > Signed-off-by: Lukasz Luba > --- > arch/arm/configs/omap2plus_defconfig | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/arch/arm/configs/omap2plus_defconfig b/arch/arm/configs/omap2plus_defconfig > index 6491419..1bbfd76 100644 > --- a/arch/arm/configs/omap2plus_defconfig > +++ b/arch/arm/configs/omap2plus_defconfig > @@ -536,7 +536,6 @@ CONFIG_DEBUG_INFO_SPLIT=y > CONFIG_DEBUG_INFO_DWARF4=y > CONFIG_MAGIC_SYSRQ=y > CONFIG_SCHEDSTATS=y > -CONFIG_PROVE_LOCKING=y > # CONFIG_DEBUG_BUGVERBOSE is not set > CONFIG_SECURITY=y > CONFIG_CRYPTO_MICHAEL_MIC=y > -- > 2.7.4 >