From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH v7 2/5] cpuset: Add cpuset.sched_load_balance to v2 Date: Wed, 2 May 2018 16:02:26 +0200 Message-ID: <20180502140226.GU12217@hirez.programming.kicks-ass.net> References: <1524145624-23655-1-git-send-email-longman@redhat.com> <1524145624-23655-3-git-send-email-longman@redhat.com> <20180502102416.GJ12180@hirez.programming.kicks-ass.net> <14d7604c-1254-1146-e2b6-23f4cc020b34@redhat.com> <20180502134225.GR12217@hirez.programming.kicks-ass.net> <94c80e1c-049d-6ec3-8e8c-40eb88d1341d@redhat.com> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=LM41facvwdAdcWlT+sVCARHogY3zOl1hiq5UQKcJaCY=; b=cUS4bgA6zI0xj359Td6zTURD0 148vvFKWkWWDVGNThKgtvKFotDDGf3kPvLbQOQLD2b5gOnVp5/xFAMpOfIMLtpntPVMvGmC1Cnum8 3dr6dJWyp/59YdX4QH/Rkp03xkYB1BQpL9hkQmQ846OrJ8nk+Pmk+GbQ5djourDJGt7rH1jAsv9ds XiiinU54TfAAjZfoy1UY7Ndf4SGvsoSV09KPExVWsrr16JXuchICDadPZoPn76cj/bAW30C9YGZ/3 zas1FUXOI7sjpct3zEPtmNL5xRf/NULdNnSzOsizTB50S5QvC+JnQXgsjKYEetFZVwf5/SmgdiIL8 Content-Disposition: inline In-Reply-To: <94c80e1c-049d-6ec3-8e8c-40eb88d1341d@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Waiman Long Cc: Tejun Heo , Li Zefan , 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 On Wed, May 02, 2018 at 09:47:00AM -0400, Waiman Long wrote: > > I've read half of the next patch that adds the isolation thing. And > > while that kludges around the whole root cgorup is magic thing, it > > doesn't help if you move the above scenario on level down: > > > > > > R > > / \ > > A B > > / \ > > C D > > > > > > R: cpus=0-7, load_balance=0 > > A: cpus=0-1, load_balance=1 > > B: cpus=2-7, load_balance=0 > > C: cpus=2-3, load_balance=1 > > D: cpus=4-7, load_balance=1 > > > > > > Also, I feel we should strive to have a minimal amount of tasks that > > cannot be moved out of the root group; the current set is far too large. > > What exactly is the use case you have in mind with loading balancing > disabled in B, but enabled in C and D? We would like to support some > sensible use cases, but not every possible combinations. Suppose A is your system group, and C and D are individual RT workloads or something. Or suppose B has siblings and each group at that level is a delegate to a particular user/container. And the user/container in B happens to need 2 partitioned VMs or whatever. The idea is the same in all the examples, you want to allow sub-partitions.