RE: 2.6.11, USB: High latency?

["kus Kusche Klaus" <kus@keba.com>]

> I couldn't find that previous email in the MARC archives.
> 
> Regardless, you'd have to provide a small bit of information about
> your hardware configuration.  What device speed:  full or high?
> What controller:  EHCI, OHCI, UHCI, something else?  Which driver
> for the stick:  usb-storage, or ub?  What else was using memory
> and PCI bandwidth at the time?  SMP?

The error occurred on an intel Pentium 3 (500 MHz) embedded system with
440BX chipset and 192 MB RAM. USB is handled by the 440BX (intel 82371
PIIX4). The UHCI driver shares interrupt 7 with an intel 82559ER 100
Mbit ethernet controller (which is driven by the e100 driver and active:
As there is no local keyboard, I access the system by ssh). 

The system "disk" is a 128 MB CF card directly connected to the 440BX
primary IDE port and running in PIO mode 2 at about 2 MB/sec peak (but
it is idle most of the time). There is a SM712 VGA chip running in text
mode, a 1000 HZ std PC timer, and no other "interesting" device (nothing
else on the PCI bus or causing any interrupts).

The error was reproduced with statically linked (no modules)
vanilla-2.6.11, 2.6.11-gentoo-r3, and
realtime-preempt-2.6.12-rc1-V0.7.41-11 kernels, all built with gcc
3.4.3. No SMP. USB-storage for the sticks.

I tried with two different sticks (an old 64 MB USB 1.x and a 1 GB USB
2.x), both show the same problem on all USB interfaces on the target.
The same dd command works fine on both sticks on my office PC. 

-- 
Klaus Kusche
Entwicklung Software - Steuerung
Software Development - Control

KEBA AG
A-4041 Linz
Gewerbepark Urfahr
Tel +43 / 732 / 7090-3120
Fax +43 / 732 / 7090-8919
E-Mail: kus@keba.com
www.keba.com
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