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wheeler scheduler and hpo

reply to recent email question about wheeler scheduler and "HPO"

early "wheeler scheduler" that i did as undergraduate ... went into cp67 ... and then dropped in the morph to vm370. i had done a bunch of "virtual memory management" stuff on cp67 at the science center.

Jack Kilby dead 803
there were frequently huge yield-volume issues ... i've observed some number of product sectors that had succesful vendors ... that were essentially ignored because of yield-volume and...

a small subset of that was incorporated into base vm370 release 3. then the resource manager ... including the wheeler scheduler ... and a whole bunch of other stuff that included a bunch of restructuring for multiprocessor work ... much of it had been done for the multiprocessor VAMPS project (which was canceled before being announced)

the resource manager was the guinee pig for first charged for kernel code.

full smp multiprocessor was released in vm370 release 4. the problem was that it was dependent on a bunch of restructuring stuff that i had smp and was already out in the resource manager. the problem was that basic kernel stuff related directly to hardware stuff was still free ... and you couldn't have free kernel (smp stuff in release 4) dependent on priced for software (lots of stuff in the resource manager). to resolve this ... about 80-90 percent of code from the resource manager was merged into the "free" kernel. come release 5 ... the remaining resource manager code (including "wheeler" scheduler) was combined with multiple shadow table support and a couple other things for "HPO".

the base kernel was still free ... but the "add-ons" were priced software.

the original cp67 support for virtual machines that supported (virtual) virtual memory ... just kept a single set of shadow page tables around (per virtual machine). The initial HPO code (combined with what had been called the resource manager) kept around multiple sets of shadow page tables (per virtual machine, when running mvs with multiple virtual address spaces ... you didn't have to completely invalidate all the shadow table entries whenever mvs switched address spaces ... you could keep around more state information)

as an aside ... ECPS was done in release 3 plc4

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