From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org by pdx-caf-mail.web.codeaurora.org (Dovecot) with LMTP id lZnpJ4tKGFvaDgAAmS7hNA ; Wed, 06 Jun 2018 20:56:43 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 801A26089E; Wed, 6 Jun 2018 20:56:43 +0000 (UTC) Authentication-Results: smtp.codeaurora.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="bt3lmGMx" X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on pdx-caf-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, MAILING_LIST_MULTI,T_DKIM_INVALID autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by smtp.codeaurora.org (Postfix) with ESMTP id 0107C605BD; Wed, 6 Jun 2018 20:56:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 0107C605BD Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752674AbeFFU4k (ORCPT + 25 others); Wed, 6 Jun 2018 16:56:40 -0400 Received: from mail-yw0-f195.google.com ([209.85.161.195]:44092 "EHLO mail-yw0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751885AbeFFU4i (ORCPT ); Wed, 6 Jun 2018 16:56:38 -0400 Received: by mail-yw0-f195.google.com with SMTP id p14-v6so2327833ywm.11; Wed, 06 Jun 2018 13:56:38 -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=oEq8RfKwJYuD+6COTlowiE5qVzPl8iEYjnmxgan8HMs=; b=bt3lmGMx2YHf5xMnHKL7hZivSOnPbNPPFFO1DnI5xOtjZqFQPJv2ha3VnWwu1Scew9 Nn2vGjpB7GVKOMqtk/TtVaWCp9tSwh+QJVGcJreo479iM/lYEuDf6+Cw+L2FYDruia/A LjcXiSpTq05dTABV/IBBDYVoVKuaCMmK3vLwenjkGAl1bDj2WtpOiaVPvL25mUDggr/s A6h9FEnmVT9gQXeBkI/5OG1rdyUj8zsWZqKNOc8hoXjkEmKvtW0XraAoJM4IX3jmIRkr piT0IPuYP9FccblRJKKe+/QJVhL58zKtVO1odXG8dlOU6LeoT2BDJOE7WqKEw7OyCKZE 60RA== 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=oEq8RfKwJYuD+6COTlowiE5qVzPl8iEYjnmxgan8HMs=; b=OrR28pw6y6Lnm5+ubtbIUaMf3vT9JGP4/I0jgdY2DyNlkCLOLPsbpXnGi1rl6Ai0T+ SRDBfRM010cAGeeybK2XNbAhlOPDnvAEivsfxUivk8SV8yIZE4K4fubBDurAWL49sEgq 1EW1o6xABoRJ6YjrSKBMAArgG7oupa91/5SYL40XE9auJn02uJu0pCe2bmFz5ds+yyc6 pzvmUkD1Yy3i2uTVkRDEH0D3yY3AbrQEY6zQ0KfssbdG0Ms4iLR4zePeQd5CvI4imMEw SKaETpHRJ8JknTi1Wa6vMFR1yF7XLcjvhhmqopVbErbboAhohNCwN0t8xr2a4BJHwrK/ sikw== X-Gm-Message-State: APt69E0OmxTHxMBRv+bjfE2R/hoDXJ5RXghpQgX0c2yOXDq2Ueffi//Z 2a9sORo3Uiq3POoJ456amN8= X-Google-Smtp-Source: ADUXVKJTN28TqIHc8oGfgoLEabx5SJbHqjMhlFJ9bV9eEiS9wybEHlOqoiJLGcxwBJxZ7RyuawgiFg== X-Received: by 2002:a0d:d757:: with SMTP id z84-v6mr2140065ywd.284.1528318597867; Wed, 06 Jun 2018 13:56:37 -0700 (PDT) Received: from localhost ([2620:10d:c091:200::d0a1]) by smtp.gmail.com with ESMTPSA id x125-v6sm22877720ywf.106.2018.06.06.13.56.36 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 06 Jun 2018 13:56:36 -0700 (PDT) Date: Wed, 6 Jun 2018 13:56:35 -0700 From: Tejun Heo To: Peter Zijlstra Cc: Waiman Long , Zefan Li , Johannes Weiner , Ingo Molnar , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kernel-team@fb.com, pjt@google.com, luto@amacapital.net, Mike Galbraith , torvalds@linux-foundation.org, Roman Gushchin , Juri Lelli , Patrick Bellasi Subject: Re: [PATCH] cpuset: Enforce that a child's cpus must be a subset of the parent Message-ID: <20180606205635.GP1351649@devbig577.frc2.facebook.com> References: <1527687991-1431-1-git-send-email-longman@redhat.com> <5B0F4F09.9050100@huawei.com> <5B0FAE72.1090204@huawei.com> <20180531082613.GF12180@hirez.programming.kicks-ass.net> <5B0FB58C.9030705@huawei.com> <4dc718bc-4bd5-4998-853b-9c6ba67b89a0@redhat.com> <20180531155807.GU1351649@devbig577.frc2.facebook.com> <20180531161645.GN12180@hirez.programming.kicks-ass.net> <20180531161942.GW1351649@devbig577.frc2.facebook.com> <20180531163826.GO12180@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180531163826.GO12180@hirez.programming.kicks-ass.net> 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, Peter. Sorry about late reply. On Thu, May 31, 2018 at 06:38:26PM +0200, Peter Zijlstra wrote: > > Yeah, for cpuset, it's messier, but it isn't different from hotunplug > > scenario, right? I think the best we can do there is putting ancestor > > operation on an equal footing as hotplug ops. > > Right, but hotplug is exceedingly rare, while I get the impression you > think it is perfectly fine to recind on your resource grants. Well, yeah, for a trivial example, imagine dynamic workload management where you wanna restrict what a side-loaded batch workload can do on and off peak hours. All other controllers can do that. It'd be a really odd design trade-off if we make that really clumsy for cpuset especially given that we wouldn't be gaining any actual functionalities. Thanks. -- tejun