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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 DBF86C76188 for ; Fri, 19 Jul 2019 08:18:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BA5872184E for ; Fri, 19 Jul 2019 08:18:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726995AbfGSISe (ORCPT ); Fri, 19 Jul 2019 04:18:34 -0400 Received: from mail-qt1-f193.google.com ([209.85.160.193]:44148 "EHLO mail-qt1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725853AbfGSISe (ORCPT ); Fri, 19 Jul 2019 04:18:34 -0400 Received: by mail-qt1-f193.google.com with SMTP id 44so2499332qtg.11 for ; Fri, 19 Jul 2019 01:18:33 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=sTL+cs2lCU2NM5qKSibXk5W13Ib4qYAgGUjbL1vgnqk=; b=PVLTM3IIgNf4QOkDnjj9dygS4hpnr40ceknSnxGWE4ZHqogYdPd3vGNrc2WJZeZjpr WZF6CSHymbroIPeIzlLxMuveUPgtqEldv6bsA18PWLScgdbsd5Reqh4JnyeluvSBcqGM B6sPb+pcIylIKyKER0dC3TuD67wXqXKtHQdVsCKOJFAeZAvy4uCXUQrnkY1RKrifpdHr Nyp6rV83oZt4Vx22IzMpf1IZpYR6IuAecFaE3lWGv/wzWOYFOCMdE3MjzoaLrdZIqzXH Eq8MMJSV9xfDVrrqU8tn4/Sliv7TfAc9To6hV3vtAgREYQWoAXlZiHYytW39qGvyJxit VPVw== X-Gm-Message-State: APjAAAW9sXvlTPtnsnt3A78A3hK+uNulrHwdvpXUhGuduj0XHj6uahTg qMamhAuTex6ZQl862+ZG7t2B1xELioY= X-Google-Smtp-Source: APXvYqyOVP03NX9J+wWs9KFySkhmqrZ2DbvfcP3TV14OEgsQszifz1DBOqmtzYEIUWDpFuxkJs37EQ== X-Received: by 2002:a0c:afd5:: with SMTP id t21mr36606870qvc.105.1563524313146; Fri, 19 Jul 2019 01:18:33 -0700 (PDT) Received: from t460s.bristot.redhat.com (host53-206-dynamic.53-79-r.retail.telecomitalia.it. [79.53.206.53]) by smtp.gmail.com with ESMTPSA id u16sm15479646qte.32.2019.07.19.01.18.30 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Fri, 19 Jul 2019 01:18:32 -0700 (PDT) Subject: Re: [PATCH v2] sched/core: Fix cpu controller for !RT_GROUP_SCHED To: Juri Lelli , peterz@infradead.org, mingo@redhat.com, tj@kernel.org Cc: rostedt@goodmis.org, linux-kernel@vger.kernel.org, luca.abeni@santannapisa.it, lizefan@huawei.com, longman@redhat.com, cgroups@vger.kernel.org References: <20190719063455.27328-1-juri.lelli@redhat.com> From: Daniel Bristot de Oliveira Message-ID: Date: Fri, 19 Jul 2019 10:18:28 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190719063455.27328-1-juri.lelli@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 19/07/2019 08:34, Juri Lelli wrote: > On !CONFIG_RT_GROUP_SCHED configurations it is currently not possible to > move RT tasks between cgroups to which cpu controller has been attached; > but it is oddly possible to first move tasks around and then make them > RT (setschedule to FIFO/RR). > > E.g.: > > # mkdir /sys/fs/cgroup/cpu,cpuacct/group1 > # chrt -fp 10 $$ > # echo $$ > /sys/fs/cgroup/cpu,cpuacct/group1/tasks > bash: echo: write error: Invalid argument > # chrt -op 0 $$ > # echo $$ > /sys/fs/cgroup/cpu,cpuacct/group1/tasks > # chrt -fp 10 $$ > # cat /sys/fs/cgroup/cpu,cpuacct/group1/tasks > 2345 > 2598 > # chrt -p 2345 > pid 2345's current scheduling policy: SCHED_FIFO > pid 2345's current scheduling priority: 10 > > Also, as Michal noted, it is currently not possible to enable cpu > controller on unified hierarchy with !CONFIG_RT_GROUP_SCHED (if there > are any kernel RT threads in root cgroup, they can't be migrated to the > newly created cpu controller's root in cgroup_update_dfl_csses()). > > Existing code comes with a comment saying the "we don't support RT-tasks > being in separate groups". Such comment is however stale and belongs to > pre-RT_GROUP_SCHED times. Also, it doesn't make much sense for > !RT_GROUP_ SCHED configurations, since checks related to RT bandwidth > are not performed at all in these cases. > > Make moving RT tasks between cpu controller groups viable by removing > special case check for RT (and DEADLINE) tasks. > > Signed-off-by: Juri Lelli > Reviewed-by: Michal Koutný Reviewed-by: Daniel Bristot de Oliveira Thanks! -- Daniel