LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Tejun Heo <tj@kernel.org>
To: Waiman Long <longman@redhat.com>
Cc: Li Zefan <lizefan@huawei.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Peter Zijlstra <peterz@infradead.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, efault@gmx.de,
	torvalds@linux-foundation.org, Roman Gushchin <guro@fb.com>
Subject: Re: [PATCH v5 2/2] cpuset: Add cpuset.flags control knob to v2
Date: Tue, 20 Mar 2018 13:22:47 -0700	[thread overview]
Message-ID: <20180320202247.GQ519464@devbig577.frc2.facebook.com> (raw)
In-Reply-To: <cbe9b852-80b6-8341-b51c-4d754d00ce53@redhat.com>

Hello, Waiman.

On Tue, Mar 20, 2018 at 04:12:25PM -0400, Waiman Long wrote:
> After some thought, I am planning to impose the following additional
> constraints on how sched_load_balance works in v2.
> 
> 1) sched_load_balance will be made hierarchical, the child will inherit
> the flag from its parent.
> 2) cpu_exclusive will be implicitly associated with sched_load_balance.
> IOW, sched_load_balance => !cpu_exclusive, and !sched_load_balance =>
> cpu_exclusive.
> 3) sched_load_balance cannot be 1 on a child if it is 0 on the parent.
> 
> With these changes, sched_load_balance will have to be set by the parent
> and so will not be delegatable. Please let me know your thought on that.

So, for configurations, we usually don't let them interact across
hierarchy because that can lead to configurations surprise-changing
and delegated children locking the parent into the current config.

This case could be different and as long as we always guarantee that
an ancestor isn't limited by its descendants in what it can configure,
it should be okay (e.g. an ancestor should always be able to turn on
sched_load_balance regardless of how the descendants are configured).

Hmmm... can you explain why sched_load_balance needs to behave this
way?

Thanks.

-- 
tejun

  reply	other threads:[~2018-03-20 20:22 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-15 21:20 [PATCH v5 0/2] cpuset: Enable cpuset controller in default hierarchy Waiman Long
2018-03-15 21:20 ` [PATCH v5 1/2] " Waiman Long
2018-03-19 15:59   ` Tejun Heo
2018-03-20 13:51     ` Waiman Long
2018-03-20 20:10       ` Tejun Heo
2018-03-20 20:53         ` Waiman Long
2018-03-20 21:14           ` Tejun Heo
2018-03-20 22:01             ` Waiman Long
2018-03-15 21:20 ` [PATCH v5 2/2] cpuset: Add cpuset.flags control knob to v2 Waiman Long
2018-03-19 16:26   ` Tejun Heo
2018-03-19 16:33     ` Waiman Long
2018-03-20 20:12       ` Waiman Long
2018-03-20 20:22         ` Tejun Heo [this message]
2018-03-20 20:43           ` Waiman Long

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20180320202247.GQ519464@devbig577.frc2.facebook.com \
    --to=tj@kernel.org \
    --cc=cgroups@vger.kernel.org \
    --cc=efault@gmx.de \
    --cc=guro@fb.com \
    --cc=hannes@cmpxchg.org \
    --cc=kernel-team@fb.com \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=lizefan@huawei.com \
    --cc=longman@redhat.com \
    --cc=luto@amacapital.net \
    --cc=mingo@redhat.com \
    --cc=peterz@infradead.org \
    --cc=pjt@google.com \
    --cc=torvalds@linux-foundation.org \
    --subject='Re: [PATCH v5 2/2] cpuset: Add cpuset.flags control knob to v2' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).