linux-kernel - Re: [PATCH v3 0/2] Reduce CPU consumption after panic

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Message-Id: <20250429133941.063544bb4731df0ef802440c@linux-foundation.org>
Date: Tue, 29 Apr 2025 13:39:41 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: carlos.bilbao@...nel.org
Cc: tglx@...utronix.de, seanjc@...gle.com, jan.glauber@...il.com,
 bilbao@...edu, pmladek@...e.com, jani.nikula@...el.com,
 linux-kernel@...r.kernel.org, gregkh@...uxfoundation.org,
 takakura@...inux.co.jp, john.ogness@...utronix.de, x86@...nel.org
Subject: Re: [PATCH v3 0/2] Reduce CPU consumption after panic

(cc more x86 people)

On Tue, 29 Apr 2025 10:06:36 -0500 carlos.bilbao@...nel.org wrote:

> From: Carlos Bilbao <carlos.bilbao@...nel.org>
> 
> Provide a priority-based mechanism to set the behavior of the kernel at
> the post-panic stage -- the current default is a waste of CPU except for
> cases with console that generate insightful output.
> 
> In v1 cover letter [1], I illustrated the potential to reduce unnecessary
> CPU resources with an experiment with VMs, reducing more than 70% of CPU
> usage. The main delta of v2 [2] was that, instead of a weak function that
> archs can overwrite, we provided a flexible priority-based mechanism
> (following suggestions by Sean Christopherson), panic_set_handling().
> 

An effect of this is that the blinky light will never again occur on
any x86, I think?  I don't know what might the effects of changing such
longstanding behavior.

Also, why was the `priority' feature added?  It has no effect in this
patchset.