linuxaudio.org

On Tue, Mar 24, 2009 at 11:39:03PM -0700, Ken Restivo wrote:

quoted text
> Is it possible that the USB protocol sets a *minimum* on latency,

> and thus any speed improvements in the USB hardware are essentially

> moot, limited by this lower bound imposed by the USB protocol?

Yes, there is a lower bound.  It depends on the protocol version being

used.
Also, don't blindly believe the latency values displayed, as these may

be estimates.  If you have the means, measure the latency using external

analysis.
--
Diversion.
We've been reading about USB latency in the past couple of days on the

One Laptop Per Child project, where USB to Ethernet devices are attached

to tiny school servers.  If you'd like to follow the technical details

...
Problem statement:

http://lists.laptop.org/pipermail/devel/2009-March/023887.html
Solution:

http://lists.laptop.org/pipermail/server-devel/2009-March/003105.html

(it was a USB 1.1 device)
And for the truly interested, the wireless chipset is also on USB, and

the Linux kernel appears to do half the possible data rate, given that

the OpenFirmware can achieve so much more with full control of the

hardware:
http://lists.laptop.org/pipermail/devel/2009-March/023899.html
(the data rate that is achieved by the kernel is well within the needs

of the target market though).
--

James Cameron    mailto:quozl@us.netrek.org     http://quozl.netrek.org/

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