🚀 go-pugleaf

>OK, so which of the OSes that support working set scheduling do so
>without having to be told by some external agent what the working set of
>a process at some given time is?  (Do the VMS calls even tell the OS
>that, or do they just tell it how big the working set is?)

It may have gotten lost: Gould NP1 UNIX.
The NP1 hardware supports reference bits.


>Jerry Leichter claimed that the VMS software people showed that a
>reference bit is not necessary, given the appropriate algorithms; does
>VMS how have appropriate algorithms to determine the contents of the
>working set without requiring a reference bit, or did the designers
>decide that the appropriate algorithm is to believe what the user or the
>application tells you and not try to figure it out for yourself?  (Not a
>rhetorical question - I'm willing to accept that the latter is the
>appropriate algorithm, given sufficient evidence to demonstrate that
>claim.)

Simulate reference bits by making the page non-RW, and faulting when you
try to read - voila, a reference, and then you just make the page readable.
Similarly, simulate modify bits by making the page non-W...
    I posted a reference to a SPUR paper that discusses the HW/SW tradeoffs
involved, yesterday.
--
Andy "Krazy" Glew,  Motorola MCD,    	    	    aglew@urbana.mcd.mot.com
1101 E. University, Urbana, IL 61801, USA.          {uunet!,}uiucuxc!udc!aglew
   
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