From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nate Lawson Subject: Re: Entering C3 Processor State without a Bus Arbiter Date: Thu, 15 Jan 2004 15:52:12 -0800 (PST) Sender: acpi-devel-admin-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Message-ID: <20040115154555.V73140@root.org> References: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Return-path: In-Reply-To: Errors-To: acpi-devel-admin-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: Dino Klein Cc: acpi-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-acpi@vger.kernel.org On Thu, 15 Jan 2004, Dino Klein wrote: > I'm curios as to why the implementation does not enter C3 without the > presence of a Bus Arbiter; also, how come a comment in the source claims > that C3/WBINVD is too expensive? > > After removing the restrictions in the source files, and adding a WBINVD > instruction right before the read from P_LVL3 - the processor was put in > the C3 state. This is on my Via Apollo Pro133A based Abit VP6 board, > which does not have a Bus Arbiter. Just for the record, I did pull out > the second CPU, so I can do "safer" experimentation. WBINVD is too expensive when you're entering C3 hundreds of times per second. Try playing back an mp3 while dd'ing a CDROM in PIO mode to your hard drive. Goodbye data, hello backups! The CPU can't snoop the bus in C3. > I've seen a thread talking about how the processor was not put into C3 > as often enough, when the USB drivers were loaded - in my case I would > say that it was put too often, this with the UHCI + EHCI + HID drivers > loaded, and two mice and one hub attached. Um, because without BM detection, you're entering C3 with BM active while USB is enabled. -Nate ------------------------------------------------------- The SF.Net email is sponsored by EclipseCon 2004 Premiere Conference on Open Tools Development and Integration See the breadth of Eclipse activity. February 3-5 in Anaheim, CA. http://www.eclipsecon.org/osdn