Path: utzoo!utgpu!watserv1!watdragon!lion!ccplumb
From: ccplumb@lion.waterloo.edu (Colin Plumb)
Newsgroups: comp.sys.transputer
Subject: Re:  info
Message-ID: <20953@watdragon.waterloo.edu>
Date: 15 Feb 90 22:53:34 GMT
References: <9002151831.AA11345@tbag.osc.edu>
Sender: daemon@watdragon.waterloo.edu
Reply-To: ccplumb@lion.waterloo.edu (Colin Plumb)
Organization: U. of Waterloo, Ontario
Lines: 19

In article <9002151831.AA11345@tbag.osc.edu> gdburns@TBAG.OSC.EDU (Greg Burns) writes:
> Since you mentioned putting a real operating system on a chip, what
> is the Qix policy on the old bad pointer crashes system transputer
> problem and what is the Qix policy on multiple users sharing a chip?

As John said, Qix allocates processors to users so you can isolate the
effects of a crash.  You can share processors if you really want to,
although the calls have all changed since I was at Cogent and I can't
tell you the details.  The allocation is dynamic so you can grab all
the chips for a few seconds of heavy grinding.

If a chip crashes in a resource server, the bus controller (a dedicated
T414 which manages the link switches) notices that it's not being sent
heartbeat messages any more and reboots the offending chip.  In a
workstation, if the main processor crashes, there's not a lot anyone
can do, but that's why the workstations have two processors: so you can
run risky stuff on the slave, which the master can kick if it's down :-).
-- 
	-Colin