From: Waiman Long <llong@redhat.com>
To: "Michal Koutný" <mkoutny@suse.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 12:27:58 -0400 [thread overview]
Message-ID: <f1afbd9e-d16b-c972-c3c0-022a05cec2a6@redhat.com> (raw)
In-Reply-To: <20210728160900.GA8905@blackbody.suse.cz>
On 7/28/21 12:09 PM, Michal Koutný wrote:
> 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.
PRS_ERROR cannot be passed to update_prstate(). For this patchset,
PRS_ERROR can only be set by changes in hotplug. The current design will
maintain the set flag (CS_SCHED_LOAD_BALANCE) and use it to decide to
switch back to PRS_ENABLED or PRS_ISOLATED when the cpus are available
again.
Cheers,
Longman
next prev parent reply other threads:[~2021-07-28 16:28 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
2021-07-28 16:27 ` Waiman Long [this message]
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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