linux-kernel - RE: [RFT][PATCH v1] cpuidle: teo: Avoid selecting deepest idle state over-eagerly

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Message-ID: <003a01db7e98$2e9ad770$8bd08650$@telus.net>
Date: Thu, 13 Feb 2025 20:23:21 -0800
From: "Doug Smythies" <dsmythies@...us.net>
To: "'Christian Loehle'" <christian.loehle@....com>,
	"'Rafael J. Wysocki'" <rjw@...ysocki.net>,
	"'Linux PM'" <linux-pm@...r.kernel.org>
Cc: "'LKML'" <linux-kernel@...r.kernel.org>,
	"'Daniel Lezcano'" <daniel.lezcano@...aro.org>,
	"'Artem Bityutskiy'" <artem.bityutskiy@...ux.intel.com>,
	"'Aboorva Devarajan'" <aboorvad@...ux.ibm.com>,
	"Doug Smythies" <dsmythies@...us.net>
Subject: RE: [RFT][PATCH v1] cpuidle: teo: Avoid selecting deepest idle state over-eagerly

Hi Christian,

Thank you for trying to repeat my idle test results.

On 2025.02.13 06:07 Christian Loehle wrote:

> I'm curious, are Doug's numbers reproducible?
> Or could you share the idle state usage numbers? Is that explainable?
> Seems like a lot and it does worry me that I can't reproduce anything
> as drastic.

While I am having some severe repeatability issues with my testing,
not for this test.

Please recall my test conditions because the CPU frequency
scaling governor does matter. I was using "performance".
The power comes from the high amount of time in idle state 1.
I verified the idle state 1 power use by disabling all other idle states.
I also have HWP disabled, but do not know if it matters.
If I use the "powersave" governor (driver is intel_pstate, not
intel_cpufreq) then idle power is < 2 watts.

Anyway, my data:

http://smythies.com/~doug/linux/idle/teo-6.14/idle/perf/

> (Idle numbers aren't really reflective in energy used -> dominated by
> active power.)

Well, it depends on idle time verses active time on the computer.
I also measured the difference in the mains power at 20%, from
43.2 watts to 51.4 watts.

I am about to send a long email with all of my test results.
Since I can not seem to function without making graphs,
it has a lot of links to graphs.