linux-kernel - Re: [PATCH RFC v2 00/22] cpuset: rework local partition logic

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Message-ID: <01a859a8-c678-4fd3-8d01-f45759c61c72@redhat.com>
Date: Tue, 11 Nov 2025 23:19:55 -0500
From: Waiman Long <llong@...hat.com>
To: Chen Ridong <chenridong@...weicloud.com>, tj@...nel.org,
 hannes@...xchg.org, mkoutny@...e.com
Cc: cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
 lujialin4@...wei.com, chenridong@...wei.com
Subject: Re: [PATCH RFC v2 00/22] cpuset: rework local partition logic


On 11/11/25 11:11 PM, Chen Ridong wrote:
>
> On 2025/11/3 19:18, Chen Ridong wrote:
>>
>> On 2025/10/25 14:48, Chen Ridong wrote:
>>> From: Chen Ridong <chenridong@...wei.com>
>>>
>>> The current local partition implementation consolidates all operations
>>> (enable, disable, invalidate, and update) within the large
>>> update_parent_effective_cpumask() function, which exceeds 300 lines.
>>> This monolithic approach has become increasingly difficult to understand
>>> and maintain. Additionally, partition-related fields are updated in
>>> multiple locations, leading to redundant code and potential corner case
>>> oversights.
>>>
>>> This patch series refactors the local partition logic by separating
>>> operations into dedicated functions: local_partition_enable(),
>>> local_partition_disable(), and local_partition_update(), creating
>>> symmetry with the existing remote partition infrastructure.
>>>
>>> The series is organized as follows:
>>>
>>> 1. Fix a bug that isolcpus stat in root partition.
>>>
>>> 2. Infrastructure Preparation (Patches 2-3):
>>>     - Code cleanup and preparation for the refactoring work
>>>
>>> 3. Introduce partition operation helpers (Patches 4-6):
>>>     - Intoduce out partition_enable(), partition_disable(), and
>>>       partition_update() functions.
>>>
>>> 4. Use new helpers for remote partition (Patches 7-9)
>>>
>>> 5. Local Partition Implementation (Patches 10-13):
>>>     - Separate update_parent_effective_cpumask() into dedicated functions:
>>>       * local_partition_enable()
>>>       * local_partition_disable()
>>>       * local_partition_invalidate()
>>>       * local_partition_update()
>>>
>>> 6. Optimization and Cleanup (Patches 14-22):
>>>     - Remove redundant partition-related operations
>>>     - Additional optimizations based on the new architecture
>>>
>>> ---
>>>
>>> Changes in v2:
>>> - Added bugfix for root partition isolcpus at series start.
>>> - Completed helper function implementations when first introduced.
>>> - Split larger patches into smaller, more reviewable units.
>>> - Incorporated feedback from Longman.
>>>
>>> Chen Ridong (22):
>>>    cpuset: fix isolcpus stay in root when isolated partition changes to
>>>      root
>>>    cpuset: add early empty cpumask check in partition_xcpus_add/del
>>>    cpuset: generalize validate_partition() interface
>>>    cpuset: introduce partition_enable()
>>>    cpuset: introduce partition_disable()
>>>    cpuset: introduce partition_update()
>>>    cpuset: use partition_enable() for remote partition enablement
>>>    cpuset: use partition_disable() for remote partition disablement
>>>    cpuset: use partition_update() for remote partition update
>>>    cpuset: introduce local_partition_enable()
>>>    cpuset: introduce local_partition_disable()
>>>    cpuset: introduce local_partition_invalidate()
>>>    cpuset: introduce local_partition_update()
>>>    cpuset: remove update_parent_effective_cpumask
>>>    cpuset: remove redundant partition field updates
>>>    cpuset: simplify partition update logic for hotplug tasks
>>>    cpuset: unify local partition disable and invalidate
>>>    cpuset: use partition_disable for compute_partition_effective_cpumask
>>>    cpuset: use validate_local_partition in local_partition_enable
>>>    cpuset: introduce validate_remote_partition
>>>    cpuset: simplify update_prstate() function
>>>    cpuset: remove prs_err clear when notify_partition_change
>>>
>>>   kernel/cgroup/cpuset.c | 1000 +++++++++++++++++++---------------------
>>>   1 file changed, 463 insertions(+), 537 deletions(-)
>>>
>> Hi Longman,
>>
>> I'd appreciate it if you could have a look at this series when you have a moment.
>>
> Hi Longman,
>
> Could you kindly take a look at this series when you have a moment?
> I'd appreciate any feedback you might have, and I’ll update the series accordingly.

I will take a look at this series tomorrow, though it has to be updated 
again anyway.

Cheers,
Longman

>