[fedora-arm] smsc95xx performance bug: eth vs usb

[Niels de Vos]

On Wed, Jun 1, 2011 at 8:59 PM, DJ Delorie <dj at redhat.com> wrote:
>
>> Or does it happen with reads too?
>
> With both the sata drive (sda) and flash drive (sdb) (both usb)
> connected, and network (also usb) up and running, I did some raw read
> tests:
>
> dd if=/dev/sda1 of=/dev/null bs=4096 count=102400
> dd if=/dev/sdb1 of=/dev/null bs=4096 count=102400
>
> sda              9.4  MB/sec
> sda+ping        23.4
>
> sdb              7.8
> sdb+ping        21.3
>
> both            14.7 each (29.4 total)
> both+ping       14.0 each (28.0 total)
>
> So, the problem seems to happen if you have one usb-storage active and
> no other usb activity, but other activity (either another usb-storage
> or ethernet pings) seems to work around the problem.

You also confirmed that one usb-storage and, quoting you:
> a serial port connected to a 9600 baud character generator,
> and got good performance.  Likewise with a usb mouse, as long as I
> wiggled the mouse during the test.

Were you referring to an onboard serial port ttyS or ttyO, or a ttyUSB?