linux-kernel - Re: [PATCH] workqueue: show the latest function name in /proc/PID/{comm,stat,status}

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Message-ID: <aCYOCYsXisQH6mi_@mtj.duckdns.org>
Date: Thu, 15 May 2025 11:53:45 -0400
From: Tejun Heo <tj@...nel.org>
To: Muchun Song <songmuchun@...edance.com>
Cc: jiangshanlai@...il.com, linux-kernel@...r.kernel.org,
	muchun.song@...ux.dev
Subject: Re: [PATCH] workqueue: show the latest function name in
 /proc/PID/{comm,stat,status}

Hello, Muchun.

On Thu, May 15, 2025 at 12:05:23PM +0800, Muchun Song wrote:
> Workqueues, such as system_unbound_wq, are shared across the system,
> making it difficult to determine which tasks are being executed by
> each worker. This patch improves clarity by displaying the latest
> function name associated with each workqueue worker in the
> /proc/PID/{comm,stat,status}. For example:
> 
> Before:
>   # ps 64 67 68
>   PID TTY STAT TIME COMMAND
>   64  ?   I    0:00 [kworker/u34:0-events_unbound]
>   67  ?   I    0:00 [kworker/u33:1-events_unbound]
>   68  ?   I    0:00 [kworker/u33:2-events_unbound]
> 
> After:
>   # ps 64 67 68
>   PID TTY STAT TIME COMMAND
>   64  ?   I    0:00 [kworker/u34:0-events_unbound:flush_memcg_stats_dwork]
>   67  ?   I    0:00 [kworker/u33:1-events_unbound:flush_to_ldisc]
>   68  ?   I    0:00 [kworker/u33:2-events_unbound:idle_cull_fn]
> 
> This change provides a clearer view of the tasks being performed by
> each worker, enhancing system monitoring and debugging.

One worry I have about this is that these will likely be stale most of the
time as kworkers are just sitting and waiting, and there's no connection
between what a kworker ran before and what it's going to run next, so I'm
unsure how useful the extra information is.

Thanks.

-- 
tejun