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From: Peter Zijlstra <peterz@infradead.org>
To: Waiman Long <longman@redhat.com>
Cc: Tejun Heo <tj@kernel.org>, Li Zefan <lizefan@huawei.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Ingo Molnar <mingo@redhat.com>,
	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 <efault@gmx.de>,
	torvalds@linux-foundation.org, Roman Gushchin <guro@fb.com>,
	Juri Lelli <juri.lelli@redhat.com>
Subject: Re: [PATCH v7 2/5] cpuset: Add cpuset.sched_load_balance to v2
Date: Wed, 2 May 2018 16:02:26 +0200	[thread overview]
Message-ID: <20180502140226.GU12217@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <94c80e1c-049d-6ec3-8e8c-40eb88d1341d@redhat.com>

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.

WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Waiman Long <longman@redhat.com>
Cc: Tejun Heo <tj@kernel.org>, Li Zefan <lizefan@huawei.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Ingo Molnar <mingo@redhat.com>,
	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 <efault@gmx.de>,
	torvalds@linux-foundation.org, Roman Gushchin <guro@fb.com>,
	Juri Lelli <juri.lelli@redhat.com>
Subject: Re: [PATCH v7 2/5] cpuset: Add cpuset.sched_load_balance to v2
Date: Wed, 2 May 2018 16:02:26 +0200	[thread overview]
Message-ID: <20180502140226.GU12217@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <94c80e1c-049d-6ec3-8e8c-40eb88d1341d@redhat.com>

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.
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  reply	other threads:[~2018-05-02 14:02 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-19 13:46 [PATCH v7 0/5] cpuset: Enable cpuset controller in default hierarchy Waiman Long
2018-04-19 13:46 ` Waiman Long
2018-04-19 13:47 ` [PATCH v7 1/5] " Waiman Long
2018-04-19 13:47   ` Waiman Long
2018-04-19 13:47 ` [PATCH v7 2/5] cpuset: Add cpuset.sched_load_balance to v2 Waiman Long
2018-04-19 13:47   ` Waiman Long
2018-05-02 10:24   ` Peter Zijlstra
2018-05-02 10:24     ` Peter Zijlstra
2018-05-02 13:29     ` Waiman Long
2018-05-02 13:29       ` Waiman Long
2018-05-02 13:42       ` Peter Zijlstra
2018-05-02 13:42         ` Peter Zijlstra
2018-05-02 13:47         ` Waiman Long
2018-05-02 13:47           ` Waiman Long
2018-05-02 14:02           ` Peter Zijlstra [this message]
2018-05-02 14:02             ` Peter Zijlstra
2018-05-02 14:35             ` Mike Galbraith
2018-05-02 14:35               ` Mike Galbraith
2018-04-19 13:47 ` [PATCH v7 3/5] cpuset: Add a root-only cpus.isolated v2 control file Waiman Long
2018-04-19 13:47   ` Waiman Long
2018-04-23 15:56   ` Juri Lelli
2018-04-23 15:56     ` Juri Lelli
2018-05-02 14:08   ` Peter Zijlstra
2018-05-02 14:08     ` Peter Zijlstra
2018-05-08  0:30     ` Waiman Long
2018-05-08  0:30       ` Waiman Long
2018-04-19 13:47 ` [PATCH v7 4/5] cpuset: Restrict load balancing off cpus to subset of cpus.isolated Waiman Long
2018-04-19 13:47   ` Waiman Long
2018-05-01 19:51   ` Tejun Heo
2018-05-01 19:51     ` Tejun Heo
2018-05-01 20:33     ` Waiman Long
2018-05-01 20:33       ` Waiman Long
2018-05-01 20:58       ` Tejun Heo
2018-05-01 20:58         ` Tejun Heo
2018-05-01 21:31         ` Waiman Long
2018-05-01 21:31           ` Waiman Long
2018-04-19 13:47 ` [PATCH v7 5/5] cpuset: Make generate_sched_domains() recognize isolated_cpus Waiman Long
2018-04-19 13:47   ` Waiman Long
2018-04-20  8:23 ` [PATCH v7 0/5] cpuset: Enable cpuset controller in default hierarchy Mike Galbraith
2018-04-20  8:23   ` Mike Galbraith
2018-04-23 16:32   ` Waiman Long
2018-04-23 16:32     ` Waiman Long
2018-04-23 13:07 ` Juri Lelli
2018-04-23 13:07   ` Juri Lelli
2018-04-23 13:57   ` Juri Lelli
2018-04-23 13:57     ` Juri Lelli
2018-04-23 14:10     ` Waiman Long
2018-04-23 14:10       ` Waiman Long

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