From cmcl2!rutgers!uwm.edu!cs.utexas.edu!uunet!ibmsupt.uucp!bass.paloalto.ibm.com!webb Tue Aug  7 10:06:08 EDT 1990
Article 2148 of comp.sys.ibm.pc.rt:
Path: cmcl2!rutgers!uwm.edu!cs.utexas.edu!uunet!ibmsupt.uucp!bass.paloalto.ibm.com!webb
>From: webb@bass.paloalto.ibm.com (Bill Webb)
Newsgroups: comp.sys.ibm.pc.rt
Subject: Re: 6152 coprocessor card(s?)
Message-ID: <1990Aug6.184720.24494@ibmpa>
Date: 6 Aug 90 18:47:20 GMT
References: <5417@uwm.edu> <F?.1.n91@cs.psu.edu> <5535@uwm.edu>
Sender: news@ibmpa (news id)
Reply-To: uunet!ibmsupt!webb (Bill Webb)
Organization: IBM AWD Paloalto
Lines: 304


In article <5535@uwm.edu>, jgreco@archimedes.math.uwm.edu (Joe Greco) writes:
|> In comp.sys.ibm.pc.rt article <F?.1.n91@cs.psu.edu>,
ehrlich@cs.psu.edu (Dan &) wrote:
|> :
|> :The Dec. '88 Release of AOS 4.3 supports 2 CPUs in and RT 6152.  I do not
|> :know if IBM every released any instructions although I vaguely remember
|> :seeing them drift by some where.  If memory serves, one also needs a
|> :modified version of the 6152 configuration diskette (the one with the
|> :diagnostics) so the bus addresses of the second CPU card can be set.  One
|> :CPU could be used to run the X server leaving the other for more useful
|> :computations.
|> Is there any other configuration possible?  I'm somewhat more interested in 
|> distributed computing applications, and doubling your processing power is
|> always nice.  :-)
|> :
|> :Joe> Anybody gots any comments?  ;-)
|> :
|> :Hope this helps.
|> It's a good start!   ;-)  Thanks.
|> :
|> ... Joe

Aha, somebody finally noticed that! I had intended to post this quite
a while back but as usual, until somebody brought it up I had forgotten
about it. I had sent out a beta-test of these instructions which was
probably what Dan had seen, but hadn't heard back anything so it just
slipped until now.

Please note that the multiple cpu stuff is completely UNSUPPORTED by 
IBM - it was a personal project that was sufficently far advanced to 
get code into the product but was much too late for the documentation
and testing required for a supported feature. This feature is not exactly
secret as it was demo'ed at the fall 1988 COMDEX as a technology demo
with the two Risc bus masters running BSD 4.3 on top of OS/2 (sigh).

There is also a paper that I'm going to present at the IBM internal Unix
conference next week, as it is not IBM CONFIDENTIAL I hope that I can
also post that here as well. 

In any case, if anybody goes attempt to get a multiple-cpu system
going please send me email with the results.

In any case here are some notes on how it is implemented followed by 
the instructions for how one builds a multi-cpu IBM 6152 system.
Enjoy! Again - this is NOT a suported feature - use at your own risk
etc. etc.

Multiple CPU Architecture for 6152

-       processors run independently of each other, each runs its
        own copy of IBM 4.3/6152.

-       primary cpu (cpu 0) owns real devices (lan, printer
        tape, asy, etc)

-       all cpu's share disks (hard, floppy, optical)
        but only 1 cpu writes to a given hard disk partition.

-       supports 1 or 2 additional processor cards, easiest
        case is 2 (total) cards each of which has its "own" disk.

-       access to "other" processor's disk is via read-only
        mount, or via NFS.

-       I/O support program (unix.exe) runs under DOS or OS/2
        which handles disk and most other I/O.

-       based on PS/2 model 60 (normal 6152 configuration with 
        additional processor cards). Also runs on model 80.

-       a software "microchannel" device implements a network 
        connection between cpu's. The primary cpu acts as a gateway
        to connect the secondary cpu's to other machines.

-       Unix drivers exist to allow other processor's memory to be
        accessed and the CPU's to be controlled.

-       minimal Unix kernel changes from latest ship kernel.

Performance

-       cpu bound jobs run with no appreciable degradation
        compared to conventional 6152's (each processor has 
        2, 4, or 8 meg of private memory). All processors do NOT
        have to have the same memory size.

-       I/O bound jobs compete for the same resources such as disk
        and are degraded, though total I/O thruput is higher. A
        model 80 helps as the 286 cpu becomes a bottleneck.

-       kernel compile that took 53 minutes with 1 cpu, took 
        30 minutes with 2 and 30 minutes with 3. It appeared to
        be disk bound with 3 cpu's.

-       sharing of work between processors was done at a high-level
        with a tool "mc" that one specifies as the C compiler to
        make (e.g.: make "CC=mc cc" )

-       my setup is to use X11 window manager and have a window
        for each secondary cpu.

-       many X benchmarks give almost 2x performance when the 
        benchmark and server run on different cpu's.

DOS implementation details

-       one copy of unix.exe runs, with various structures changed
        to have one-per-cpu. Implements a Hot-key (to switch the
        keyboard, screens, mouse, and speaker from one CPU to another).

-       halt/reboot requests are no-ops from any cpu but cpu 0.

-       code provided to allow secondary cpu's to be automatically started
        from primary cpu as part of normal boot sequence.

-       "main loop" looks for requests from both cpu's; generally services
        each in turn.

-       about 1 week's effort to get first version working; about 1 month's
        effort after that to fix bugs and add necessary features.

-       code is in shipable state.

-       runs on DOS 3.3 and has been run (once) on DOS 4.0

OS/2 implementation details

-       one instance of unix.exe runs per cpu; each runs in its own
        full-screen session.

-       uses standard OS/2 hot-key to switch between cpu's (and other OS/2
        sessions).

-       runs on OS/2 Version 1.1 (presentation manager) and 1.0
        but disk performance is much better with 1.1.

-       microchannel driver implemented using OS/2 shared memory segment.

-       disk performance is good, network performance and "microchannel
        driver" performance needs work (about 10x slower than DOS version).

-       needs additional work to be "proper" OS/2 program (totally event
        driven), currently uses polling for requests from Risc processor that 
        would best be event-driven threads. This would help performance
        and reduce the drag on background tasks.

Other

-       the second cpu is very handy for kernel develepment and performance
        measurements as one can be working on code on the main cpu and 
        running tests or debugging on the other cpu. I've found it nice
        to be able to recover from installing a kernel with a fatal bug
        from home without having someone on site.
----------------------------------------------------------------
Instructions on how to build a mutiple-cpu 6152:


-	assumes that you already have a 6152 with one cpu

-	obtain an aditional cpu (possibly by removing it from
	another 6152)

-	install the December release of 6152 system (or at least
	the kernel, boot, and unix.exe from December), you will
	also need the December /usr/bin/X11/Xibm as it knows how
	to save the screen on hot-key events.

-	install the new @8ff7.adf file onto the reference disk
	working copy (e.g. via doswrite -va @8ff7.adf):


------------------------------------------------------------

AdapterId 8ff7h

AdapterName  "RISC coprocessor card"

NumBytes 4

NamedItem Prompt "I/O port"
	Choice "01e0-01ef"
		pos[3]=00011110b
		pos[0]=00000001b
		pos[1]=00011110b
		io 01e0h-01eFh
		int 7
		arb 14
	Choice "01f0-01ff"
		pos[3]=00011111b
		pos[0]=00000001b
		pos[1]=00011100b
		io 01f0h-01fFh
		int 7
		arb 12
	Choice "200-20f"
		pos[3]=00100000b
		pos[0]=00000001b
		pos[1]=00011010b
		io 200h-20Fh
		int 7
		arb 10
	Choice "Disabled"
		pos[3]=11111111b
		pos[0]=00000000b
		pos[1]=00000000b
	Help 
"Default I/O address is 1e0. <Disabled>
 disables the adapter."
------------------------------------------------------------

-	install the additional processor card, and then use the
	reference diskette to autoconfigure the system. If the 
	two processors have different amounts of memory the first
	one (port 0x1e0) should have the larger amount of memory,
	as that is where one usually runs the X server.

-	the simplest installation will have two processors, each
	of which will have a disk drive for its own use (you will
	need a root and a swap for each processor, but /usr can 
	be shared, either via mounting it read-only, or via nfs).

	For simplicity I will assume that each disk has the normal
	root, swap, and /usr partitions.

-	create two new host names, e.g. if the original system was 'frodo'
	then create frodo-mc0, and frodo-mc1. frodo-mc0 will be the 
	gateway machine for cpu1 to the rest of the world. (You should
	use your local naming conventions if they are different from
	what we use).

-	the hd1 disk can be created by cloning the hd0 disk, e.g.
	use fdisk and minidisk to create the DOS/BIOS partition and
	the unix partitions respectively and then copy the unix
	partitions via the normal newfs/dump/restore mechanism.
	e.g.
		newfs -v hd1a
		mount /dev/hd1a /mnt
		cd /mnt
		dump 0f - / | restore rvf - 
		cd /
		umount /dev/hd1a

		newfs -v hd1g
		mount /dev/hd1g /mnt
		cd /mnt
		dump 0f - /usr | restore rvf - 
		cd /
		umount /dev/hd1g

-	change /etc/rc.config on hd1 to reflect the new hostname
	and network address, e.g. change network and hostname entries
	to:

	network='mc0'
	hostname='frodo-mc1'

-	on the hd0 disk, add the following lines to rc.config, so that
	we make frodo into a gateway (this may require allocating a new
	network number for 'frodo')

	network_2='mc0'
	hostname_2='frodo-mc0'
	net_flags_2="$net_flags"

-	now you can boot up the system. Note that when unix.exe starts
	it will tell you that you have 2 processors. The first processor
	should now be able to come up normally. Once it gets to the login
	state you can hot-key to the second processor (control-alt-esc),
	and boot it. It should come up on the second disk by default
	(e.g. boot hd(1,0)vmunix.) 

-	if everything has worked properly you can add a line to /etc/rc.config
	so that the second cpu is automatically started when the first is
	about to go multiuser. This is done by specifying:

	ipl_cpu=1

	in /etc/rc.config.

-	if one wants to reboot the second cpu, one can do so by first
	halting or rebooting it (e.g. /etc/halt or /etc/reboot), and
	then issing the following commands (on cpu 0):

		/etc/por 1
		/etc/load /boot
		/etc/ipl 1
		
	(note that you must put the 6152 version of boot into /boot
	rather than the RT version).

-	note that messages about the state of the second cpu are displayed
	on the console of the master cpu so that one can determine that 
	has halted or attempted to reboot.

-	note that if your configuration file doesn't have the line
	device mc0 at iocc0 csr 0xffffffff priority 13
	then it will need to be added in order to send packets between
	the two Risc cpu's.

------------------------------------------------------------
The above views are my own, not those of my employer.
Bill Webb (IBM AWD Palo Alto), (415) 855-4457.
UUCP: ...!uunet!ibmsupt!webb


