Re: [gentoo-user] Does USB devices share bandwidth?

[sternklang gentoo]

Hi,

If there are only two ports on the card, there is almost certainly a single
hub controller on the card, so they would share the available bandwidth.
That would be a max of 12Mbits/second for 1.1.

On 6/22/06, Caster <cast3r@×××××.com> wrote:
>
> On 6/22/06, 张|武 <zhangweiwu@××××××.com> wrote:
> >
> > Hello. My old sparc server have a USB extension card, which provides two
> > USB slots at the back of the machine, driving a USB printer on Slot A.
> > This printer runs at heavy load. because it cannot print the documents
> > as fast as we need, I wish to add another printer. In most casese, we
> > need the two printer working together the same time rather then one
> > after the other.
> >
> > The two USB slots provided by the USB card are both OHCI (some USB 1.x
> > stuff, not USB 2.0). So far it seems one single printer uses up all the
> > USB bandwidth (sometimes printer stop there several seconds wait for
> > signal). What would happen if I put another Printer there?
> >
> > case A: the new printer uses the bandwidth on slot B, both run as fast
> > as if they were the only USB printer;
> > case B: the new printer share bandwidth with the old one, the result is
> > both printer work 1/2 fast, that is equal to not having bought another
> > printer at all.
> >
> > Which one is true?
> >
> > Thanks in advance:)
> >
> > --
> > gentoo-user@g.o mailing list
> >
> >
>
> According to http://www.sounddevices.com/tech/usbbasics.htm if the ports
> are on the same controller, they share bandwith. It probably depends on the
> hardware if it provides controller for each port or not. I think mostly it's
> two ports per controller, but dunno how to determine it... From lspci, and
> lsusb I would think that in my case (nforce4ultra) it's only one controller,
> but to share 10 ports ? Nonsense. In windows it shows 5 devices, which would
> correspond with the idea of 2 ports per controller... but dunno how to see
> that in linux.
> You could probably plug some usb flash storage in and perform transfers to
> see if it slows down the printing, to be sure :)
>
> Caster
>



-- 
sternklang
sternklang.gentoo@×××××.com