All of lore.kernel.org
 help / color / mirror / Atom feed
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


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

Thread overview: 43+ 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
2021-07-20 14:18   ` Waiman Long
2021-07-26 22:56   ` Tejun Heo
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
2021-07-20 14:18   ` Waiman Long
2021-07-26 22:59   ` Tejun Heo
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
2021-07-20 14:18   ` Waiman Long
2021-07-26 23:14   ` Tejun Heo
2021-07-27 20:26     ` Waiman Long
2021-07-27 20:26       ` Waiman Long
2021-07-27 20:46       ` 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   ` Waiman Long
2021-07-20 14:18 ` [PATCH v3 6/9] cgroup/cpuset: Add a new isolated cpus.partition type Waiman Long
2021-07-20 14:18   ` Waiman Long
2021-07-27 11:42   ` Frederic Weisbecker
2021-07-27 15:56     ` Waiman Long
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
2021-07-28 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   ` 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   ` Waiman Long
2021-07-20 14:18 ` [PATCH v3 9/9] kselftest/cgroup: Add cpuset v2 partition root state test Waiman Long
2021-07-20 14:18   ` Waiman Long
2021-07-26 23:17 ` [PATCH v3 0/9] cgroup/cpuset: Add new cpuset partition type & empty effecitve cpus Tejun Heo
2021-07-26 23:17   ` Tejun Heo
2021-07-27 21:14   ` Waiman Long
2021-08-09 22:46     ` Tejun Heo
2021-08-10  1:12       ` Waiman Long
2021-08-10  1:12         ` 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=f1afbd9e-d16b-c972-c3c0-022a05cec2a6@redhat.com \
    --to=llong@redhat.com \
    --cc=akpm@linux-foundation.org \
    --cc=cgroups@vger.kernel.org \
    --cc=corbet@lwn.net \
    --cc=frederic@kernel.org \
    --cc=guro@fb.com \
    --cc=hannes@cmpxchg.org \
    --cc=juri.lelli@redhat.com \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-kselftest@vger.kernel.org \
    --cc=lizefan.x@bytedance.com \
    --cc=mkoutny@suse.com \
    --cc=mtosatti@redhat.com \
    --cc=pauld@redhat.com \
    --cc=peterz@infradead.org \
    --cc=shuah@kernel.org \
    --cc=tj@kernel.org \
    /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
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.