linux-kernel - Re: [PATCH v4 0/2] sched/numa: add statistics of numa balance task migration

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Message-ID: <2648c494-8eff-4841-b942-4f538f1f5eca@linux.ibm.com>
Date: Wed, 7 May 2025 20:58:18 +0530
From: Venkat Rao Bagalkote <venkat88@...ux.ibm.com>
To: "Chen, Yu C" <yu.c.chen@...el.com>
Cc: mkoutny@...e.com, Ingo Molnar <mingo@...hat.com>,
        Tejun Heo <tj@...nel.org>, Johannes Weiner <hannes@...xchg.org>,
        Jonathan Corbet <corbet@....net>, Mel Gorman <mgorman@...e.de>,
        Michal Hocko <mhocko@...nel.org>, Muchun Song <muchun.song@...ux.dev>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Shakeel Butt <shakeel.butt@...ux.dev>,
        "Chen, Tim C" <tim.c.chen@...el.com>, Aubrey Li <aubrey.li@...el.com>,
        Libo Chen <libo.chen@...cle.com>,
        K Prateek Nayak <kprateek.nayak@....com>,
        Madadi Vineeth Reddy <vineethr@...ux.ibm.com>,
        "Jain, Ayush"
 <ayushjai@....com>, cgroups@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Chen Yu <yu.chen.surf@...mail.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v4 0/2] sched/numa: add statistics of numa balance task
 migration


On 07/05/25 8:22 pm, Chen, Yu C wrote:
> Hi Venkat,
>
> On 5/7/2025 10:32 PM, Venkat Rao Bagalkote wrote:
>> Hello Chenyu,
>>
>>
>> On 07/05/25 4:44 pm, Chen Yu wrote:
>>> Introducing the task migration and swap statistics in the following 
>>> places:
>>> /sys/fs/cgroup/{GROUP}/memory.stat
>>> /proc/{PID}/sched
>>> /proc/vmstat
>>>
>>> These statistics facilitate a rapid evaluation of the performance 
>>> and resource
>>> utilization of the target workload.
>>>
>>> Patch 1 is a fix from Libo to avoid task swapping for kernel threads,
>>> because Numa balance only cares about the user pages via VMA.
>>>
>>> Patch 2 is the major change to expose the statistics of task 
>>> migration and
>>> swapping in corresponding files.
>>>
>>> The reason to fold patch 1 and patch 2 into 1 patch set is that 
>>> patch 1 is
>>> necessary for patch 2 to avoid accessing a NULL mm_struct from a kernel
>>> thread, which causes NULL pointer exception.
>>>
>>> The Tested-by and Acked-by tags are preserved, because these tags 
>>> are provided
>>> in version 1 which has the p->mm check.
>>
>> I see below tags from version 1 are missing. I think, its 
>> contridicting to the above line. Please correct me, If I am wrong.
>>
>>
>> Tested-by: Madadi Vineeth Reddy <vineethr@...ux.ibm.com>
>> Tested-by: K Prateek Nayak <kprateek.nayak@....com>
>>
>
> These tags are in the patch 2/2, because Madadi and Prateek mainly
> tested patch 2/2.


Understood. Thanks for clarification.

>
>>
>> For some reason, I am not able to apply this patch on top of 
>> next-20250506. I see patch002 fails to apply. Please find the errors 
>> below.
>>
>
> next-20250507 should be OK(I just checked on top of commit 08710e696081).
> next-20250506 might still have the old patch 2/2, and next-20250507 has
> reverted it.
>
With next-20250507, there is a build issue [1] 
<https://lore.kernel.org/all/1bcc235f-b139-4423-a7bd-2dd16065e08c@linux.ibm.com/> 
, I will test this, once the build issue fixed.


Regards,

Venkat.

> thanks,
> Chenyu