[Info-vax] CRTL and RMS vs SSIO

[Simon Clubley]

On 2021-10-08, Lawrence D?Oliveiro <lawrencedo99 at gmail.com> wrote:
> On Saturday, October 9, 2021 at 4:37:26 AM UTC+13, Stephen Hoffman wrote:
>> Having looked at this back in the VAX era, the slow process creations 
>> our apps were incurring were arising from inefficiencies within the DCL 
>> spawn-related processing, and not from within the OpenVMS process 
>> creation overhead. 
>> 
>> Once that was identified and the obvious work-around implemented, 
>> spawns were pretty speedy even VAX-era. 
>> 
>> To Simon's comment, how DCL gets mapped into process address space is 
>> just ugly, too. And hard to debug.
>
> But the whole reason why DCL maps into a process in this way, so that user-mode code can be repeatedly loaded, run and then wiped from the same process, was precisely to avoid multiple process creations. Now you are saying that the DCL mechanism itself contributes to the overhead of process creations!
>

Sort-of wiped. Turns out that's a rather important difference. :-)

BTW, spawn is when you actually do want a new subprocess for some
reason. Not the same thing as loading an image into the existing
DCL process.

Simon.

-- 
Simon Clubley, clubley at remove_me.eisner.decus.org-Earth.UFP
Walking destinations on a map are further away than they appear.