gc-by-area and host uptimes

[Jeffrey Mark Siskind <Qobi@ZERMATT.LCS.MIT.EDU>]

        It is currently broken for Genera of all versions.

Thats a shame. I really hope that Symbolics changes their mind and chooses
to fix and support. Please read on.

        With the advent of
        :Start GC :Immediately By-Area, there's no pressing need for it either.

I disagree. As my previous mail relates, my experience is that using gc-by-area
requires a significant amount of hand-holding to do several iterations of GC.
This takes a lot of time, and also puts a burden on the user to make a lot
of decisions along the way. Even then there is no guarantee that there aren't
so many references that cross areas to make gc'ing a small subset of them at
a time of any use.

        By the way, it was actually pretty fast for the early Ivories, since there
        were no "real concerns" of working set, etc.  But it's attrociously slow
        on a full system, taking two to twelve hours (without-interrupts) for a
        typical dynamic GC.

That doesn't bother me. Several gc-by-areas takes me also twelve hours. During
that time I am dead affraid to touch my machine for fear that I might cons
and destroy the saftey predictions of the GC mechanism. I'd rather be able to do
that unattendend over night or during the weekend. For all I care a GC that
took 72 hours that I ran once every two or three months wouldn't be that bad
at all.

        I was explicitly vague about all of this on the public list because I
        really didn't want to commit to shipping or supporting anything like this
        in the forseeable future.  There's an awful lot of work involved in making
        this into something that's near the quality of the system GC.

    Thanks for the info. I dont think a mere mention of a hack implies the
    future requirement for shipping or supporting; a disclaimer that it does
    not work, is dangerous, etc., is not intended for users, should quiet
    most folks from even asking for it.

Not me, I am still asking for it, based on the fact that I beleive that it
is a good idea irrespective of its implementation status.

    Then, your comment that :Start GC
    :Immediately By-Area superceding its use or need can also be your final
    comment on the matter.

I hope that it is not the final comment on the matter.

    I was just lobbying for letting folks know
    things, otherwise rumors get around and become stupid. You might end up
    finding that you are being accused of hoarding an important tool that
    solves all virtual memory problems ever considered, when in fact it
    never even did what they thought it did...