[HECnet] Another TOPS-10 DECnet problem

[Thomas DeBellis]

Oh, that old cat fight?  Meow!!  I'm walking away from it; I don't know 
how much email got spewed between MRC and BAH about it.  I don't think 
either side ever got the point that you are not comparing apples to apples.

Having looked at both schedulers, I don't immediately see that either 
was more efficient than the other.  There clearly was cross 
fertilization in a number of areas.

Recall that Tops-20 has processes and that a job may have a large number 
of processes.  The number of jobs then is not going to be a valid 
comparison.  For example, let's take a look at Galaxy on Tops-10, which 
occupies 10 job slots:

Job    Who     Line#    What   Size(P) State   Run Time

  1    [OPR]     DET     NEBULA  26+40   HB 0
  3    [OPR]      0      QUEUE   9+38    ^C 1
  7    [OPR]     DET     QUASAR  40+40   SL 1
  9    [OPR]     DET     PULSAR  5+40    HB SW 0
10    [OPR]     DET     ORION   109+40  SL 0
11    [OPR]     DET     NML     15+18   HB 3
13    [OPR]     DET     CDRIVE  30+40   HB 0
14    [OPR]     DET     FAL-10  104+40  SL 1


They're all underneath a _single_ job on Tops-20 or built into the EXEÇ, 
but producing the same load because it is the same code.

We did do some instrumenting and we found that the snazzy parsing 
(COMND%) was not contributing that much to load.  There was some 
overhead simulating UUO's, which are obviously natively executing on 
Tops-10.  Nearly all editing was done with WYSIWYG video editing, which 
surely must produce more load than TECO or SOS.  Some work was put into 
TEXTI% to mitigate the context switching.

MRC's position was that Tops-20 was doing more, but I'm not sure how 
comfortable I am with that.  Having used and programmed both, I think 
it's more like 'doing differently'.  I would say that it was rare to 
find people who could easily move between the two and/or who weren't 
highly opinionated.

It's a waste of time; you bought what did the job best for your 
environment.  It's kind of like apples and pineapples; they sound the 
same but they're just not.
------------------------------------------------------------------------
On 11/11/21 5:20 PM, Robert Armstrong wrote:
>
> >You had a 20 that would handle 600 students in 1977/???/
>
>   I think he said something about six 20s…  I’m pretty sure there’s no 
> way one CPU would have handled 600 timesharing users.   We could get 
> to around 120 on a single KL10E with TOPS-10 before it got unbearably 
> slow.  With TOPS-20 on the same hardware we could only get to 80 or 
> so; TOPS20 was something of a pig.
>
> Bob
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.sonic.net/pipermail/hecnet-list/attachments/20211111/28756f1a/attachment-0001.htm>