USB hub provoked slowdown.

Ian FREISLICH ianf at clue.co.za
Mon Nov 5 20:27:06 PST 2007


Rui Paulo wrote:
> 
> On 5 Nov 2007, at 12:59, Ian FREISLICH wrote:
> 
> > 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
> 
> A couple of questions:
> 1) Are you using kbdmux?
Yes.

> 2) Does the CPU usage go up when you plug the keyboard OR when you  
> plug the mouse ? Or when both are connected?

The keyboard and mouse have no effect.

> 3) Do you see any change just by plugging the USB hub?

All running processes utilization goes up when the hub is plugged
in.  Their utilization returns to normal when the hub is unplugged.

Ian

--
Ian Freislich



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