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

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Message-ID: <c4757667-6d6a-4010-80c5-f5203630557a@intel.com>
Date: Wed, 7 May 2025 22:52:18 +0800
From: "Chen, Yu C" <yu.c.chen@...el.com>
To: Venkat Rao Bagalkote <venkat88@...ux.ibm.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

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.

> 
> 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.

thanks,
Chenyu