DEC Ada tasks and multiprocessors

DEC Ada tasks and multiprocessors

[Mats Weber]

We are running VMS 6.2 on Alpha's with multiple processors. We can't
upgrade to VMS 7.1 now due to our customer's constraints (it's a large
system with peripherals that are not yet ready for VMS 7.1 (drivers,
etc.)).

We are using DEC Ada 3.3 for AXP, and our current problem is that we
cannot use multiple processors for the Ada tasks in a single Ada
program. We do not want to split the application into multiple
programs/processes because that would be too much work.

I know that GNAT for VMS/alpha is soon to be released, but for VMS 7.1.
We would be ready to change to GNAT, but we can't do the 7.1 upgrade
now.

Is there really no way (perhaps by changing the Ada run time library ?)
to make a single Ada program on VMS 6.2/alpha use multiple processors ?

Thanks for any answers/suggestions

Re: DEC Ada tasks and multiprocessors

[Larry Kilgallen]

In article <338453EE.15F0@elca-matrix.ch>, Mats Weber <Mats.Weber@elca-matrix.ch> writes:

> We are using DEC Ada 3.3 for AXP, and our current problem is that we
> cannot use multiple processors for the Ada tasks in a single Ada
> program. We do not want to split the application into multiple
> programs/processes because that would be too much work.

A single process on VMS V6 can only use one CPU at a time.
That is an operating system constraint which has been in VMS since 1978.
The constraint is lifted on VMS V7 for Alpha.

> We are running VMS 6.2 on Alpha's with multiple processors. We can't
> upgrade to VMS 7.1 now due to our customer's constraints (it's a large
> system with peripherals that are not yet ready for VMS 7.1 (drivers,
> etc.)).

I just updated a driver which was NEVER, EVER going to run on anything
past VMS V6.2 so that it can be used on VMS V7.1 because the folks who
signed 20 year contracts for continued manufacture of a particular model
of hardware changed their mind.  Updating the driver was straightforward
because there was no need for 64-bit addressing support. A recompile
and relink (with the proper OS libraries) was all it needed.

Of course a lot of time the problem is that driver source is
controlled by a different organization which is not so interested
in upgrading.

Larry Kilgallen

Re: DEC Ada tasks and multiprocessors

[Robert Dewar]

Mats said

<<Is there really no way (perhaps by changing the Ada run time library ?)
to make a single Ada program on VMS 6.2/alpha use multiple processors ?

Thanks for any answers/suggestions>>


You would indeed have to rewrite substantial parts of the runtime library.
A very difficult task, since the necessary interfaces are undocumented

Re: DEC Ada tasks and multiprocessors

[Brendan Boulter]

Mats Weber wrote:
> 
> We are running VMS 6.2 on Alpha's with multiple processors. We can't
> upgrade to VMS 7.1 now due to our customer's constraints (it's a large
> system with peripherals that are not yet ready for VMS 7.1 (drivers,
> etc.)).
> 
> We are using DEC Ada 3.3 for AXP, and our current problem is that we
> cannot use multiple processors for the Ada tasks in a single Ada
> program. We do not want to split the application into multiple
> programs/processes because that would be too much work.
> 
> I know that GNAT for VMS/alpha is soon to be released, but for VMS 7.1.
> We would be ready to change to GNAT, but we can't do the 7.1 upgrade
> now.
> 
> Is there really no way (perhaps by changing the Ada run time library ?)
> to make a single Ada program on VMS 6.2/alpha use multiple processors ?
> 
> Thanks for any answers/suggestions