On Thursday 09 February 2006 07:32, Alan Stern wrote: > On Tue, 7 Feb 2006, Delbert Franz wrote: > > > (snip) > > > > I did an install of W2K SP4 on a 6 GB scratch IDE drive and > > found that the same temperature change occurs under MSW, > > suggesting that it is not OS dependent. I suspect it is > > in the MB firmware. > > Why do you suspect that? The firmware doesn't get involved when you > insert a USB device. Glad to know that. By firmware, in my mind, I also included the details of the on-board devices, which also may be micro programmed: > > > I then connected a watt meter to the computer and found that > > the idle power usage under Linux was about 106 watts. Inserting > > a usb key in one of the built in USB ports causes the power > > usage to jump by about 30 watts, to a total of about 136. Of course > > it does not take long for the CPU temp to rise by about 4 degrees C. > > However, the CPU load shows no change. The power usage and the > > temperature rise remain when the usb key is removed. Only a reboot > > will reset the system. Removing the usb-storage related modules > > might also cut the power. I have not tried that yet. Need to recompile > > every USB item as a module to do that. > > Probably you would need to remove only the host controller drivers > (uhci-hcd and ehci-hcd).
I found that unplugging the key and then doing: rmmod ehci_hcd, drops the power usage again. > > (snip) > > > I get the same behavior on another computer, built on an Asus > > A8V which uses a K8T800Pro chipset. Both computers use an AMI > > Bios and both use a VT8237 chip for USB. I guess it should not > > be a surprise that they both display similar behavior on this issue. > > The VIA USB host controller chips have some very questionable behavior. > Look at the email threads on this page: > > http://marc.theaimsgroup.com/?a=113508574400006&r=1&w=2 > > > Questions: > > > > 1. Has anyone else detected this behavior on these or other > > motherboards? > > > > 2. Is it reasonable to assume that the behavior stems from some > > implementation detail in the chipset/BIOS? > > Chipset, yes. BIOS, no. > > > 3. Why does the insertion of a usb key in a builtin port > > require 30 watts more power from the CPU???? This is more than > > half the increase from idle caused by loading the CPU with a large > > numerical simulation application:)! > > Why do you think the increased power is all being used by the CPU? Why > couldn't it be used by the USB host controller (and partly by the USB key > itself)? It seemed logical to me that most of the power was dissipated by the CPU, because its temperature rose by about 4 degrees C. The power usage by the key is small compared to 30 wattts. > > > 4. What is going on in the CPU that the CPU load meter does not > > change even though 30 watts more power is being dissipated? > > Insertion of a USB device prevents the CPU from entering certain low-power > states, because it forces the USB host controller to start doing DMA. So > even though the CPU isn't doing any more work computationally, it's still > using more power. > > > I currently plan to use PCI based USB ports for usb-storage > > connections--I see no need to heat the CPU so much just to do > > some I/O on the USB bus. > > Try using non-VIA components. :-) Yes, I have an old, PCI USB controller with a VIA chip on it that claims to be high speed but Linux does not recognize its high-speed mode at all:( I did buy some two-port IOGEAR USB controller cards that seem to work well. > > > Thanks for any insight into this strange behavior. I don't believe > > there is anything amiss in lm_sensors and that the problem lies in > > the USB subsystem as implemented in the VIA chipset. > > Quite likely. > > Alan Stern > > ------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Do you grep through log files for problems? Stop! Download the new AJAX search engine that makes searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! http://sel.as-us.falkag.net/sel?cmd=lnk&kid=103432&bid=230486&dat=121642 _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-users
