Really poor performance on /dev/ttyv* only

[Scott Long]

Antony Mawer wrote:
> On 1/11/2005 6:02 PM, Greg 'groggy' Lehey wrote:
> 
>> I've just installed -CURRENT on a Dell Inspiron 6000, and I discover
>> that the keyboard response on virtual terminals (/dev/ttyv*) is very
>> slow.  If I keyboard repeat, the echo to the terminal is jerky, about
>> 3 or 4 characters at a time with a marked delay in between.  Under X
>> or over the network there's no problem.  Has anybody else seen this?
>> The kernel isn't 100% GENERIC (I've disabled WITNESS and
>> WITNESS_SKIPSPIN, for example), but I can't see anything that would
>> explain this behaviour.
> 
> 
> I've seen this on two FreeBSD 4.7 systems connected via a KVM (sharing 
> with two Windows 2003 servers)... typing at the console of them was 
> almost like typing via ssh on a satellite connection. Connecting via ssh 
> was fine, it was only locally that it was a problem. Resetting the 
> keyboard repeat rate on BSD had no discernible impact.
> 
> I put it down to some sort of interaction between the KVM, the Windows 
> servers and FreeBSD and put up with it...
> 
> Cheers
> Antony
> 

I have a USB KVM that violates the USB protocol and results in a storm 
on the USB controller once in a while.  This can result in really 
sluggish console performance.  I can imagine scenarios where PS/2 KVM
could do similarily silly things with the same results.

Scott