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=-5.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, T_DKIMWL_WL_HIGH,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 6DAB6C28CC5 for ; Wed, 5 Jun 2019 13:34:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 40866206BB for ; Wed, 5 Jun 2019 13:34:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559741687; bh=o8lToEz46I/+28kwT0hSuUzum1uvFsV9UImUt4RT1B4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=pmNd3GzqeAYO41DvnBNyvTETyAeKVmtnOMJ7sakbEL9jvbri2uviAGYwK2s2o9nqh pcMAWPInmvZFLfemTtqYTzlClAN5jFoXgo4LTWvmjeAW6+yh48s//IjwRgpUXznvUz +F8jrUcrFHEiAu8JSE7g4/XkjxsKegFSmOuiMRwU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727978AbfFENeq (ORCPT ); Wed, 5 Jun 2019 09:34:46 -0400 Received: from mail-qk1-f194.google.com ([209.85.222.194]:35992 "EHLO mail-qk1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726442AbfFENep (ORCPT ); Wed, 5 Jun 2019 09:34:45 -0400 Received: by mail-qk1-f194.google.com with SMTP id g18so5134881qkl.3; Wed, 05 Jun 2019 06:34:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=grBBM9ViaanFgHPLnFrQHKU04qolbq9KsWYNsIIwRqA=; b=u107NaP8nG876tIG6Q2fL9N9piNv7X1C8ktfs1g7H/hDLqed+pH6cxVRLLRNznbtm7 Mcs4Os2HbvpEVPU71DOG2dkTQkQFj1DTVQD1xbFBWjw7WF0h97y/V1UlSvaIuFEftNWK dbxnDMpwhY3GY20Mb6DEdwg3rrwqciAvdHqjQnpRY/BolbgE4M1jaiF1ZPvawQvLAFJc mcV6vpbo4mCioqlrX32FS6meK6OqhxdlRBo/hp2jYyy/9ZG4eFC4e6hRV5mikW8QsOPd e+yXKMeMNN+lIamY359iclpNA/oUtZ93ElA4TD7urYgkhnKxGU0Z8kzqejtn6DHL6ifZ Vxsg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=grBBM9ViaanFgHPLnFrQHKU04qolbq9KsWYNsIIwRqA=; b=khGQHwe9CYIf0BQhjf5E9rh4DUxyspB4gGqGoeMAC9xVfOOK40FQz33aHP2wM+XIEI jxYfLy4F97OoDou7UN1d7WbYiGU+atVE4VM/PyuHzjmE435A4eHdOQSRm84JInqn0qUg WOqh1wGGvpdJ36PUITGmpl9E8IvCkUlRgARdlDHg8VSQclB2/QamHFP/YADmkHcHalRY 8GOJKo8P+4TI4bClX+G0zZyoZDkfBWRXByOreJS0PqtCO+e/GTzqEfvWJcTRaeNSfuW9 7IgE+KYhLd3cy8VGEe39UGSfzAOhqBmGggVXf9RtL3FfAaevpTMcC9E4/M6+z5A5EVo9 K+6g== X-Gm-Message-State: APjAAAUHeVZqrLqioCL8ap9lQ2xclXDsuvbxnHJ9Hu1Ukl0SUz8CzPws T8qvRHAQneWaS1CnLdFHOGs= X-Google-Smtp-Source: APXvYqwl1p5ZrcCZPQK3a1Eh2kpFD9I7pupsFV3QFAqHHQm23X4++11e1P8XI1bGH2GOwoL1JUr5vA== X-Received: by 2002:a37:4804:: with SMTP id v4mr34301359qka.330.1559741684282; Wed, 05 Jun 2019 06:34:44 -0700 (PDT) Received: from localhost ([2620:10d:c091:500::1:c027]) by smtp.gmail.com with ESMTPSA id d16sm13121896qtd.73.2019.06.05.06.34.43 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 05 Jun 2019 06:34:43 -0700 (PDT) Date: Wed, 5 Jun 2019 06:34:42 -0700 From: Tejun Heo To: Juri Lelli Cc: peterz@infradead.org, mingo@redhat.com, rostedt@goodmis.org, linux-kernel@vger.kernel.org, luca.abeni@santannapisa.it, bristot@redhat.com, lizefan@huawei.com, cgroups@vger.kernel.org Subject: Re: [PATCH] sched/core: Fix cpu controller for !RT_GROUP_SCHED Message-ID: <20190605133442.GJ374014@devbig004.ftw2.facebook.com> References: <20190605114935.7683-1-juri.lelli@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190605114935.7683-1-juri.lelli@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Wed, Jun 05, 2019 at 01:49:35PM +0200, 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 > > 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 > --- > Hi, > > Although I'm pretty assertive in the changelog, I actually wonder what > am I missing here and why (if) current behavior is needed and makes > sense. > > Any input? Yeah, RT tasks being transprent to the cpu controller when !RT_GROUP_SCHED makes sense to me, especially given that the rules around it are already inconsistent. Please feel free to add Acked-by: Tejun Heo Thanks. -- tejun