linux-kernel - Re: [PATCH] hung_task: Skip scan on idle systems

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Message-ID: <vwzd7i5us7ahsdyk5zb6qfv2ggsqt3oeemlbhakre5jfwjfi3h@ehbdznirzg7h>
Date: Sat, 7 Feb 2026 16:01:43 -0500
From: Aaron Tomlin <atomlin@...mlin.com>
To: Petr Mladek <pmladek@...e.com>
Cc: Lance Yang <lance.yang@...ux.dev>, neelx@...e.com, sean@...e.io, 
	mhiramat@...nel.org, akpm@...ux-foundation.org, joel.granados@...nel.org, 
	mproche@...il.com, chjohnst@...il.com, nick.lange@...il.com, 
	gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hung_task: Skip scan on idle systems

On Mon, Feb 02, 2026 at 02:55:41PM +0100, Petr Mladek wrote:
> It makes some sense. And the check of the average load is trivial
> so it might be acceptable.
> 
> But I somehow doubt that it works. Have you ever seen a system with
> (avenrun[0] == 0)? IMHO, it might be pretty hard to achieve it.
> Or maybe I am too pessimistic. Or are there embedded systems which can
> only be waken by some interrupt from a sensor? Do embedded systems
> run hung task detector?
> 
> By other words. Is this patch solving a theoretical scenario?
> Did you test it in practice, please?
> 
> Best Regards,

Hi Petr,

You are entirely correct; this was a purely theoretical proposition.

I have not validated this against a production workload to quantify any
potential savings. Achieving a load average of exactly zero is elusive in
practice on modern systems, rendering the optimisation likely ineffective.

Please consider this patch withdrawn.


Best regards,
-- 
Aaron Tomlin

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