USB hub provoked slowdown.

Ian FREISLICH ianf at clue.co.za
Mon Nov 5 05:00:19 PST 2007


Hi

On my old home system running 7.0-BETA1 - Dual P3-800, when I plug
my in-monitor (HP L1955) USB hub into my shiny new USB2 PCI card,
my entire system starts wading through molasas.

By this I mean, for example:

mplayer: ~30% cpu
xorg: ~12% cpu

Then insert molasas inducing HP monitor uhub

mplayer: ~99% cpu
xorg: ~75% cpu

Removing the hub lets the previous consumption occur.

What I don't understand is why these seemingly unrelated to usb
processes cpu utilisation goes up when I plug the uhub in.  Interrupt
and system CPU usage remains unchanged.  Plugging the keyboard and
mouse directly into the usb card works fine.

I am at a loss.

The USB card is identified as:

uhci0 at pci0:0:12:0:      class=0x0c0300 card=0x30381106 chip=0x30381106 rev=0x61 
hdr=0x00
    vendor     = 'VIA Technologies Inc'
    device     = 'VT82xxxxx UHCI USB 1.1 Controller (All VIA Chipsets)'
    class      = serial bus
    subclass   = USB
uhci1 at pci0:0:12:1:      class=0x0c0300 card=0x30381106 chip=0x30381106 rev=0x61 
hdr=0x00
    vendor     = 'VIA Technologies Inc'
    device     = 'VT82xxxxx UHCI USB 1.1 Controller (All VIA Chipsets)'
    class      = serial bus
    subclass   = USB
ehci0 at pci0:0:12:2:      class=0x0c0320 card=0x31041106 chip=0x31041106 rev=0x63 
hdr=0x00
    vendor     = 'VIA Technologies Inc'
    device     = 'VT6202/12 USB 2.0 Enhanced Host Controller'
    class      = serial bus
    subclass   = USB

The monitor's hub is identified as follows according to usbdevs:

port 2 addr 2: full speed, self powered, config 1, product 0x2504(0x2504), vendor 0x0424(0x0424), rev 0.01

Ian

--
Ian Freislich



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