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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 C479AC433ED for ; Wed, 7 Apr 2021 12:27:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 833BA611EE for ; Wed, 7 Apr 2021 12:27:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352138AbhDGM17 (ORCPT ); Wed, 7 Apr 2021 08:27:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49232 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235368AbhDGM15 (ORCPT ); Wed, 7 Apr 2021 08:27:57 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5BAD2C061756 for ; Wed, 7 Apr 2021 05:27:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=MfqgLWv10IJUoyDmm979n6kaRcDpYx7OQawOsvcvaLo=; b=ehAPGtUP0FPy1+N88OuFRTRS5r QonnsHieZ034bS3NTIN0lbiP9asu7//rg22nLKCOjhmxwUM3/PzcVscIHrVdZ0XA1cZoYoyMFkVKG yC2TasVn2Nw+b+tRFsuqqetzxo6FQnDO6t6bn4EOSedng4iJCySyO15xAVKeWpsLBIq5tsCak1gwz 2KwePxMPyVq7GcwBGCBGcPpwzGVjVrguHhGz/7D1GaoXnPyRw/qYXrT6+zY/Kd8oFAVzazRfC6De4 9s1QF7GDELhwo5RLCaY6r8TreoVEMvW3aOV9EBpnClzizoLiOFs0XiWUyqXdz8fS7N5ASQUc654ac LR2vXT8A==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1lU7Gg-00ESES-My; Wed, 07 Apr 2021 12:26:52 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 5A07D300056; Wed, 7 Apr 2021 14:26:46 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 409A6244029A1; Wed, 7 Apr 2021 14:26:46 +0200 (CEST) Date: Wed, 7 Apr 2021 14:26:46 +0200 From: Peter Zijlstra To: Valentin Schneider Cc: mingo@kernel.org, mgorman@suse.de, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, bristot@redhat.com, joshdon@google.com, linux-kernel@vger.kernel.org, greg@kroah.com Subject: Re: [PATCH 4/9] sched: Move SCHED_DEBUG to debugfs Message-ID: References: <20210326103352.603456266@infradead.org> <20210326103935.025550243@infradead.org> <87blaqnzho.mognet@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87blaqnzho.mognet@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 07, 2021 at 11:46:43AM +0100, Valentin Schneider wrote: > On 26/03/21 11:33, Peter Zijlstra wrote: > > __read_mostly bool sched_debug_enabled; > > > > +struct dentry *debugfs_sched; > > + > > static __init int sched_init_debug(void) > > { > > - debugfs_create_file("sched_features", 0644, NULL, NULL, > > - &sched_feat_fops); > > + struct dentry __maybe_unused *numa; > > + > > + debugfs_sched = debugfs_create_dir("sched", NULL); > > + > > + debugfs_create_file("features", 0644, debugfs_sched, NULL, &sched_feat_fops); > > + debugfs_create_bool("debug_enabled", 0644, debugfs_sched, &sched_debug_enabled); > > + > > Could we kill this too? I'm probably biased because I've spent some amount > of time banging my head at topology problems, but this two-tiered debugging > setup (KCONFIG + cmdline or post-boot write) has always irked me. > > I can't find the threads in a hurry, but ISTR justifications for keeping > this around were: > - Most distros have CONFIG_SCHED_DEBUG=y because knobs and ponies > - Topology debug prints are "too verbose" ^^ that mostly. > - NUMA distance matrix processing gets slower > > If we make it so distros stop / don't need to select CONFIG_SCHED_DEBUG, We're not there yet, I think :-( > then I don't think the above really stands anymore (also, sched_init_numa() > now has the same complexity regardless of sched_debug), and we could keep > everything under CONFIG_SCHED_DEBUG. But yes, the reason this knob exists is ebcause I too frequently forget to add the boot time knob, so I added this one to enable it at runtime and then I get topology prints when I hotplug cycle a cpu.