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From: "Michal Koutný" <mkoutny@suse.com>
To: Waiman Long <longman@redhat.com>
Cc: Tejun Heo <tj@kernel.org>, Zefan Li <lizefan.x@bytedance.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Jonathan Corbet <corbet@lwn.net>, Shuah Khan <shuah@kernel.org>,
	cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Roman Gushchin <guro@fb.com>, Phil Auld <pauld@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Frederic Weisbecker <frederic@kernel.org>,
	Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: [PATCH v3 6/9] cgroup/cpuset: Add a new isolated cpus.partition type
Date: Wed, 28 Jul 2021 18:09:00 +0200	[thread overview]
Message-ID: <20210728160900.GA8905@blackbody.suse.cz> (raw)
In-Reply-To: <20210720141834.10624-7-longman@redhat.com>

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Hello Waiman.

On Tue, Jul 20, 2021 at 10:18:31AM -0400, Waiman Long <longman@redhat.com> wrote:
> @@ -2026,6 +2036,22 @@ static int update_prstate(struct cpuset *cs, int new_prs)
> [...]
> +	} else if (old_prs && new_prs) {

If an isolated root partition becomes invalid (new_prs == PRS_ERROR)...

> +		/*
> +		 * A change in load balance state only, no change in cpumasks.
> +		 */
> +		update_flag(CS_SCHED_LOAD_BALANCE, cs, (new_prs != PRS_ISOLATED));

...this seems to erase information about CS_SCHED_LOAD_BALANCE zeroness.

IOW, if there's an isolated partition that becomes invalid and later
valid again (a cpu is (re)added), it will be a normal root partition
without the requested isolation, which is IMO undesired.

I may have overlooked something in broader context but it seems to me
the invalidity should be saved independently of the root/isolated type.

Regards,
Michal


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  parent reply	other threads:[~2021-07-28 16:09 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-20 14:18 [PATCH v3 0/9] cgroup/cpuset: Add new cpuset partition type & empty effecitve cpus Waiman Long
2021-07-20 14:18 ` [PATCH v3 1/9] cgroup/cpuset: Miscellaneous code cleanup Waiman Long
2021-07-26 22:56   ` Tejun Heo
2021-07-20 14:18 ` [PATCH v3 2/9] cgroup/cpuset: Fix a partition bug with hotplug Waiman Long
2021-07-26 22:59   ` Tejun Heo
2021-07-27 20:16     ` Waiman Long
2021-07-20 14:18 ` [PATCH v3 3/9] cgroup/cpuset: Fix violation of cpuset locking rule Waiman Long
2021-07-26 23:10   ` Tejun Heo
2021-07-20 14:18 ` [PATCH v3 4/9] cgroup/cpuset: Enable event notification when partition become invalid Waiman Long
2021-07-26 23:14   ` Tejun Heo
2021-07-27 20:26     ` Waiman Long
2021-07-27 20:46       ` Waiman Long
2021-07-20 14:18 ` [PATCH v3 5/9] cgroup/cpuset: Clarify the use of invalid partition root Waiman Long
2021-07-20 14:18 ` [PATCH v3 6/9] cgroup/cpuset: Add a new isolated cpus.partition type Waiman Long
2021-07-27 11:42   ` Frederic Weisbecker
2021-07-27 15:56     ` Waiman Long
2021-07-29 11:03       ` Frederic Weisbecker
2021-07-28 16:09   ` Michal Koutný [this message]
2021-07-28 16:27     ` Waiman Long
2021-07-28 17:25       ` Michal Koutný
2021-07-20 14:18 ` [PATCH v3 7/9] cgroup/cpuset: Allow non-top parent partition root to distribute out all CPUs Waiman Long
2021-07-20 14:18 ` [PATCH v3 8/9] cgroup/cpuset: Update description of cpuset.cpus.partition in cgroup-v2.rst Waiman Long
2021-07-20 14:18 ` [PATCH v3 9/9] kselftest/cgroup: Add cpuset v2 partition root state test Waiman Long
2021-07-26 23:17 ` [PATCH v3 0/9] cgroup/cpuset: Add new cpuset partition type & empty effecitve cpus Tejun Heo
2021-07-27 21:14   ` Waiman Long
2021-08-09 22:46     ` Tejun Heo
2021-08-10  1:12       ` Waiman Long

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