Date: Tue, 14 Jan 2003 16:04:43 -0500 (EST) From: John Baldwin <jhb@FreeBSD.org> To: Nate Lawson <nate@root.org> Cc: cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG, Wilko Bulte <wkb@freebie.xs4all.nl> Subject: Re: cvs commit: src/sys/dev/acpica acpi_cpu.c Message-ID: <XFMail.20030114160443.jhb@FreeBSD.org> In-Reply-To: <Pine.BSF.4.21.0301141218150.39326-100000@root.org>
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On 14-Jan-2003 Nate Lawson wrote: > On Tue, 14 Jan 2003, Wilko Bulte wrote: >> On Tue, Jan 14, 2003 at 02:54:13PM -0500, John Baldwin wrote: >> > Albeit lying. If it were just available but not enabled, then the >> > CPU wouldn't slow down when I pulled the power cord of out my laptop. >> > However, when I pull the power cord out of my laptop, the CPU does >> > slow down. Thus, it would seem rather obvious that CPU throttling >> > is most certainly enabled and not just available. >> >> How does this work on desktops? I've seen one of my P2 boxes report >> this throttling thing? >> >> Surely not the power plug being pulled out, although it slowed down >> greatly when pulled ;) > > No, that's the manual override S5 state. ;) > > Throttling on non-laptop systems can only be requested by the BIOS or OS, > I believe. On FreeBSD, that's via sysctl. Basically you have events > coming in and actions taken. When you unplug the power on a laptop, the > BIOS delivers the event to the acpi interpreter which runs the dsdt to > decide what to do. That's my basic understanding. BIOS's don't usually throttle the CPU in the DSDT AFAIK. That is done by the OS in response to the event. In FreeBSD's case, the acpi_acad(4) driver changes the system state which can result in a change in the current throttling speed. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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