Re: waking up processes on external input

["Barry Cook" <Barry@xxxxxxxxxxxx>]

Richard,

It was part of the hardware.

The low-latency from data delivery to use was a key to the Transputer's high 
performance in multi-processor configurations. Without it modern 
multiprocessors can't do as well - unless you restrict the applications you 
run on them

Input could be a data communication or an 'event'.

If the process to be put on the queue was a high priority process then the 
time from hardware signal to process running was below 1us.

Event inputs, equivalent to interrupts on traditional processors, causing 
sub-microsecond 'interrupt handler' process activation was somewhat faster 
than interrupt response times of other processors, even of today's 
Gigahertz-clock-rate CPU's!

   Barry.

Dr Barry M. Cook, BSc, PhD, CEng, MBCS, CITP, MIEEE
CTO,
4Links Limited,
The Mansion,
Bletchley Park,
MK3 6ZP,
UK.
----- Original Message ----- 
From: "Richard Tonge" <rtonge90@xxxxxxxxxxx>
To: <occam-com@xxxxxxxxxx>
Sent: Sunday, September 24, 2006 8:23 AM
Subject: waking up processes on external input


> My current understanding is that on the transputer, processes were not 
> members of the process queue when they were waiting for input from the 
> external links. This would mean that whenever input arrived, some 
> mechanism would have to add to the queue any process waiting on the link.
>
> Was this mechanism was part of the hardware, or was it done with a 
> software interrupt handler?
>
> Thanks,
>
> Richard Tonge
> Ageia Technologies inc.