Re: [PATCH RESEND -next 00/21] cpuset: rework local partition logic

[Waiman Long <llong@redhat.com>]

On 1/4/26 11:01 PM, Chen Ridong wrote:
>
> On 2025/12/25 20:30, Chen Ridong wrote:
>> From: Chen Ridong <chenridong@huawei.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. Infrastructure Preparation (Patches 1-2):
>>     - Code cleanup and preparation for the refactoring work
>>
>> 2. Introduce partition operation helpers (Patches 3-5):
>>     - Introduce out partition_enable(), partition_disable(), and
>>       partition_update() functions.
>>
>> 3. Use new helpers for remote partition (Patches 6-8)
>>
>> 4. Local Partition Implementation (Patches 9-12):
>>     - Separate update_parent_effective_cpumask() into dedicated functions:
>>       * local_partition_enable()
>>       * local_partition_disable()
>>       * local_partition_update()
>>
>> 5. Optimization and Cleanup (Patches 13-21):
>>     - Remove redundant partition-related operations
>>     - Additional optimizations based on the new architecture
>>
>> base-commit: cc3aa43b44bdb43dfbac0fcb51c56594a11338a8
>>
>> ---
>>
>> Changes in RESEND:
>> 1. Rebase on the next-20251219
>>
>> Changes from RFC v2:
>> 1. Dropped the bugfix (already merged/fixed upstream)
>> 2. Rebased onto next
>> 3. Introduced partition_switch to handle root state switches
>> 4. Directly use local_partition_disable()—no longer first introduce
>>     local_partition_invalidate() before unifying the two
>> 5. Incorporated modifications based on Longman's suggestions
>>
>> Changes in RFC v1:
>> 1. Added bugfix for root partition isolcpus at series start.
>> 2. Completed helper function implementations when first introduced.
>> 3. Split larger patches into smaller, more reviewable units.
>> 4. Incorporated feedback from Longman.
>>
>> Chen Ridong (21):
>>    cpuset: add early empty cpumask check in partition_xcpus_add/del
>>    cpuset: generalize the 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: user local_partition_disable() to invalidate local partition
>>    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: use partition_disable for compute_partition_effective_cpumask
>>    cpuset: use validate_local_partition in local_partition_enable
>>    cpuset: introduce validate_remote_partition
>>    cpuset: simplify the update_prstate() function
>>    cpuset: remove prs_err clear when notify_partition_change
>>    cpuset: Remove unnecessary validation in partition_cpus_change
>>
>>   kernel/cgroup/cpuset.c | 1023 ++++++++++++++++++----------------------
>>   1 file changed, 454 insertions(+), 569 deletions(-)
>>
> Hi Longman,
>
> This series has been out for a while. I'd appreciate it if you could take some time to review it.
>
Sorry for being late in reviewing this updated series. However, there 
are also other cpuset related patch series that are being reviewed at 
the moment. Since this is mainly a cleanup patch making the code easier 
to understand, but it does a major restructuring of the existing code 
which will likely make the other patches harder to merge. So I would 
like to prioritize the other fix and feature patches first. I will try 
to review the patches when I have time, but I want this series to be 
merged after other cpuset patches are done.

Sorry for the inconvenience caused as you may have to redo the patch 
series again when the code base is settled down.

Cheers,
Longman