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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,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 C6ECBC282C4 for ; Mon, 4 Feb 2019 20:26:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9BB2A2073D for ; Mon, 4 Feb 2019 20:26:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728342AbfBDU0I (ORCPT ); Mon, 4 Feb 2019 15:26:08 -0500 Received: from muru.com ([72.249.23.125]:37606 "EHLO muru.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726634AbfBDU0I (ORCPT ); Mon, 4 Feb 2019 15:26:08 -0500 Received: from atomide.com (localhost [127.0.0.1]) by muru.com (Postfix) with ESMTPS id C6214808C; Mon, 4 Feb 2019 20:26:16 +0000 (UTC) Date: Mon, 4 Feb 2019 12:26:04 -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: <20190204202604.GP5720@atomide.com> References: <20181009153624eucas1p2ad30aea33ad1c869f11bd9ca1156d9af~b_rxQW8J90311703117eucas1p2U@eucas1p2.samsung.com> <20181108165958.GK56134@atomide.com> <21ce2c61-0b20-41f2-4d12-3c5b1c4b7925@partner.samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <21ce2c61-0b20-41f2-4d12-3c5b1c4b7925@partner.samsung.com> User-Agent: Mutt/1.11.2 (2019-01-07) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Lukasz Luba [181113 10:22]: > Hi Tony, > > On 11/8/18 5:59 PM, Tony Lindgren wrote: > > 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. > That's common reason for a few defconfigs in mainline. Actually looks like this does not change the DEBUG related options.. I must have done something wrong earlier, sorry. So applying into omap-for-v5.1/defconfig. > > So we should take a look which ones we can or want to keep. > > Or just disable CONFIG_DEBUG completely. > Ideally, the CI should try a few 'types' of configs, > generated based on the 'defconfig'. Some 'smart' script might > cut the debug options for an image for performance regression tests. > > > > 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. Yes I think that's the case. Regards, Tony