From: Pavel Machek <pavel@ucw.cz>
To: Zhang Rui <rui.zhang@intel.com>
Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
linux-acpi@vger.kernel.org, rjw@sisk.pl, lenb@kernel.org,
eduardo.valentin@ti.com
Subject: Re: [PATCH] ACPI thermal: do not always return THERMAL_TREND_RAISING for active trip points
Date: Sat, 27 Apr 2013 12:23:47 +0200 [thread overview]
Message-ID: <20130427102346.GA30588@amd.pavel.ucw.cz> (raw)
In-Reply-To: <1366967993-3812-1-git-send-email-rui.zhang@intel.com>
Hi!
> Commit 4ae46befb49d4173122e0afa995c4e93d01948a2
> introduces a regression that the fan is always on
> even if the system is in idle state.
>
> My original idea in that commit is that:
> when the current temperature is above the trip point,
> keep the fan on, even if the temperature is dropping.
> when the current temperature is below the trip point,
> turn on the fan when the temperature is raising,
> turn off the fan when the temperature is dropping.
Is that even right algoritm?
Assume I'm running at very cold room, lets say -10C. Assume idle CPU
will hover around 30C with no fan, or hover around 10C with fan
running, trip point being 50C.
You _could_ leave fan off until 50C, having silent, passively cooled
system.
What it will do instead is annoyingly pulse fan at 10C.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
next prev parent reply other threads:[~2013-04-27 10:23 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-26 9:19 [PATCH] ACPI thermal: do not always return THERMAL_TREND_RAISING for active trip points Zhang Rui
2013-04-26 12:07 ` Rafael J. Wysocki
2013-04-27 10:23 ` Pavel Machek [this message]
2013-04-27 12:32 ` Zhang Rui
2013-04-27 18:38 ` Pavel Machek
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