linux-kernel - Re: [REGRESSION][BISECTED] Double energy consumption on idle

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Message-ID: <Z2uaFYEdPZL449_M@wunner.de>
Date: Wed, 25 Dec 2024 06:37:25 +0100
From: Lukas Wunner <lukas@...ner.de>
To: Kurt Borja <kuurtb@...il.com>
Cc: linux-crypto@...r.kernel.org, Herbert Xu <herbert@...dor.apana.org.au>,
	"David S. Miller" <davem@...emloft.net>,
	linux-kernel@...r.kernel.org
Subject: Re: [REGRESSION][BISECTED] Double energy consumption on idle

On Tue, Dec 24, 2024 at 07:42:49PM -0500, Kurt Borja wrote:
> When I first booted into v6.13 I noticed my laptop got instantly hotter
> and battery started draining fast. Today I bisected the kernel an ran
> powerstat [1]. It comes down to
> 
> Upstream commit: 6b34562f0cfe ("crypto: akcipher - Drop sign/verify operations")
> 
> These results are reproducible on my system 100% of the time, and the
> regression is still present on the latest upstream commit.
> 
> Please tell me if there is more info or test I should provide. I can
> test any patch candidates too.

The commit removes dead code and doesn't touch anything power-related.
So it's quite odd that it should cause a power regression.

Could you try reverting only this single commit and verify that the
issue goes away?  Just to double-check that this commit is really
the root cause.

> Before commit 6b34562f0cfe
> CPU:  24.94 Watts on average with standard deviation 0.21  
[...]
> After commit 6b34562f0cfe
> CPU:  57.64 Watts on average with standard deviation 0.88

That's a huge amount of extra power draw.  I'd suspect the Nvidia
discrete graphics to consume such an amount, so maybe it's not
powered down?  Have you enabled relevant Kconfig options such as
CONFIG_VGA_SWITCHEROO and CONFIG_DRM_NOUVEAU on the v6.13-rc kernel?

Thanks,

Lukas