Subject: Re: Warning to USB users
To: Jason R Thorpe <>
From: Andrew Brown <>
List: current-users
Date: 04/13/2001 15:05:40
> > In a recent change Jason Thorpe turned on an option in the USB drivers
> > that uses soft interrupts.  If a port does not have generic soft interrupts (a
> > prime example is i386) it instead uses a callout.  In the latter case the
> > interrupt latency increases greatly.  For most USB devices this has no
> > consequence, but if you are using, e.g., Ethernet adapters, the performance
> > will be pretty bad (on my machine it went from 700 KB/s to 140 KB/s).
> > If this worries you, just change sys/dev/usb/usb_port.h and comment
> > out the define of USB_USE_SOFTINTR.
>Unfortunately, SOFTINTR is going to be required due to another change
>I'm going to make today.

is this likely to be the cause of kern/12632, or is that more a form
of collateral damage?

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