[HECnet] Emulated XQ polling timer setting and data overrun

[Mark Pizzolato - Info Comm]

On Thursday, June 05, 2014 at 4:50 PM, Mark Pizzolato wrote:
On Thursday, June 05, 2014 at 4:33 PM, Johnny Billquist wrote:
On 2014-06-06 01:16, Mark Pizzolato - Info Comm wrote:
OK.   So you sound like you really need a throttling option for the
LAN
devices.   I'll look over the throttling logic in the bridge and fold
in something similar.

Well, I'm not so sure that code should be a model to pattern anything after.
Everything about my bridge is just a hack. Done just to fix an
immediate problem without any proper design at any corner. :-)

It definitely has more going for it then my first thoughts.   Before looking at
your bridge code, I was merely going to create an option to measure the time
between successive packets.   Your model allows for some bursting but then
starts throttling.

I'll make it an option and the control variables (TIMEWINDOW, BURSTSIZE,
DELAY) configurable.   Default will be no throttle.

The current simh code base has Ethernet transmit throttling support for XQ and XU devices.

The default behavior is unchanged (i.e. no throttling).

Throttling for a particular LAN interface can be enabled with:

      sim> SET {XQ|XQB|XU|XUB} THROTTLE=DISABLE
      sim> SET {XQ|XQB|XU|XUB} THROTTLE=ENABLE
      sim> SET {XQ|XQB|XU|XUB} THROTTLE=TIME=n{;BURST=n{;DELAY=n}}

Where:
                  TIME=n specifies an inter-packet gap (in ms) which can trigger throttling
                  BURST=n specifies the number of successive packets which sent with a gap < TIME will trigger throttling
                  DELAY=n specifies the number of milliseconds to delay when before transmitting the next packet

Defaults for these are TIME=5, BURST=4 and DELAY=10

The defaults were taken from Johnny's Bridge program.   Since I don't have working physical systems to test with, I'm looking for feedback on good working choices for these default values.

- Mark