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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 1D43AC433ED for ; Fri, 14 May 2021 17:55:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EF8AC61168 for ; Fri, 14 May 2021 17:55:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235285AbhENR4l (ORCPT ); Fri, 14 May 2021 13:56:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42292 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232283AbhENR4j (ORCPT ); Fri, 14 May 2021 13:56:39 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1FD54C061574; Fri, 14 May 2021 10:55:28 -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=HdZ+Rvb3VddDC+nVIUj42YinsKumWXhl2FsoYoSKcTw=; b=MlhCqueTaVBVJquCeH+yCh0mNn DWQa9KPy6TjpHwTVqGPctwkRkkm7WYcbTKbR3BnJnNQwRZm2C8UaQgPY522CQoRXLO6O+1pTV+mas dKpzpvYnQL+t4hdwCIYtN6cLPasFRXYO+UuH58XydP4dQ8L0yW79ol4kJsBmHQ5348JfDO9SSxpf8 0yeMNi8e254eAojsjvy+g1z52WWvIL3venwPje2pWY0s8kSNGvArS4VnB2jpLOoriOick18LHRkQP UuJzP9Q71riB+cDvdaQvzFEEcm1nOhmlVb9+DqMlCv6ANXJ+6XPSvnsRU9Jl0ohR2Zz9FmYy6R9+O LsYUevOQ==; 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 1lhbyp-00AakW-KA; Fri, 14 May 2021 17:52:22 +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 EB3D6300223; Fri, 14 May 2021 19:52:04 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id CE4732BA998D5; Fri, 14 May 2021 19:52:04 +0200 (CEST) Date: Fri, 14 May 2021 19:52:04 +0200 From: Peter Zijlstra To: Suren Baghdasaryan Cc: Tejun Heo , Johannes Weiner , lizefan.x@bytedance.com, Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Benjamin Segall , mgorman@suse.de, Minchan Kim , Jonathan Corbet , bristot@redhat.com, "Paul E . McKenney" , rdunlap@infradead.org, Andrew Morton , Thomas Gleixner , macro@orcam.me.uk, Viresh Kumar , mike.kravetz@oracle.com, linux-doc@vger.kernel.org, LKML , cgroups mailinglist , kernel-team Subject: Re: [PATCH 1/1] cgroup: make per-cgroup pressure stall tracking configurable Message-ID: References: <20210513175349.959661-1-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 14, 2021 at 08:54:47AM -0700, Suren Baghdasaryan wrote: > Correct, for this function CONFIG_CGROUPS=n and > cgroup_disable=pressure are treated the same. True, from the code it's > not very obvious. Do you have some refactoring in mind that would make > it more explicit? Does this make sense? --- a/kernel/sched/psi.c +++ b/kernel/sched/psi.c @@ -744,24 +744,26 @@ static void psi_group_change(struct psi_ static struct psi_group *iterate_groups(struct task_struct *task, void **iter) { + if (cgroup_psi_enabled()) { #ifdef CONFIG_CGROUPS - struct cgroup *cgroup = NULL; + struct cgroup *cgroup = NULL; - if (!*iter) - cgroup = task->cgroups->dfl_cgrp; - else if (*iter == &psi_system) - return NULL; - else - cgroup = cgroup_parent(*iter); + if (!*iter) + cgroup = task->cgroups->dfl_cgrp; + else if (*iter == &psi_system) + return NULL; + else + cgroup = cgroup_parent(*iter); - if (cgroup && cgroup_parent(cgroup)) { - *iter = cgroup; - return cgroup_psi(cgroup); - } -#else - if (*iter) - return NULL; + if (cgroup && cgroup_parent(cgroup)) { + *iter = cgroup; + return cgroup_psi(cgroup); + } #endif + } else { + if (*iter) + return NULL; + } *iter = &psi_system; return &psi_system; }