Re: Extra systems in world load

[Richard Shu <rshu@ADS.COM>]

In article <19891031210329.1.BARMAR@OCCAM.THINK.COM> barmar@THINK.COM (Barry Margolin) writes:
>
>    Date: Mon, 30 Oct 89 09:37:00 MST
>    From: intvax!gnome!drstrip@unmvax.cs.unm.edu (David R. Strip)
>
>    What are the disadvantages of adding a large, infrequently used
>    system (e.g., Macsyma) to a world load (on a 3645, to be 
>    precise)? Presumably this increases boot time, but does it
>    have other nasty performance hits once it has  been ignored for
>    a long time?
>
>It will increase the size of the world load on disk, and slightly
>increase the boot time, but it shouldn't have much effect on runtime
>performance.  Programs that aren't used will just sit on disk, waiting
>to be paged in.

I can think of a couple of cases where doing this would increase
response time for a developer.  These are:

1) Doing package DWIM
2) Doing List Callers

In both these cases, the presence of a package with many symbols
will probably cause a significantly longer response time.  I don't
know a lot about how symbols are implemented but I assume there
is a separate hash-table for each package and that the above
functionalities involve paging the hash-table for each package.

BTW, I've wondered for several years if one could effectively "unload"
software by doing a remob on all the symbols in a package.
If the number of symbols is large and many of them are functions,
would there be a significant recovery of free space?

Rich



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