🚀 go-pugleaf

Anne & Lynn Wheeler <ly...@garlic.com> writes:

> one of the things that happened in VM was that since you could operate
> the environment "with" and "with/out" the kernel, there was increased
> emphasis on kernel efficiency and performance i.e. standard operating
> systems tend to claim that the kernel pathlength is what it is, and
> maybe we can tweak it a little ... but there was significant more
> pressure on the VM kernel to keep in lean and mean. 

simple example is between the time that CP/67 was installed at the
university in jan, 1968 where I was an undergraduate and the time I
made presentation at the August '68 SHARE meeting in Boston, I had
reduced many CP/67 pathlengths by a factor of ten to one hundred
times. the following is from that '68 share presentation.

The original CP/67 kernel CPU consumption to execute the referenced OS
MFT14 virtual machine was 856-322 or 534 cpu seconds. By August, I had
rewritten several portions of the kernel and reduced the total CP/67
kernel CPU consumption to 435-322 or 113 cpu seconds for an overall
reduction of a factor of five times (I had also replaced the page
replacement algorithm with a clock-like algorithm, implemented
original fair share scheduling, and done misc. other improvements).


                     OS Performance Studies With CP/67

OS              MFT 14, OS nucleus with 100 entry trace table, 105 record
                in-core job queue, default IBM in-core modules, nucleus total
                size 82k, job scheduler 100k.

HASP            118k Hasp with 1/3 2314 track buffering

Job Stream      25 FORTG compiles

Bare machine    Time to run: 322 sec. (12.9 sec/job)
   times        Time to run just JCL for above: 292 sec. (11.7 sec/job)

Orig. CP/67     Time to run: 856 sec. (34.2 sec/job)
   times        Time to run just JCL for above: 787 sec. (31.5 sec/job)

                Ratio   CP/67 to bare machine

                2.65    Run FORTG compiles
                2.7     to run just JCL
                2.2     Total time less JCL time

1 user, OS on with all of core available less CP/67 program.

Note:   No jobs run with the original CP/67 had ratio times higher than
        the job scheduler. For example, the same 25 jobs were run under WATFOR,
        where they were compiled and executed. Bare machine time was 20 secs.,
        CP/67 time was 44 sec. or a ratio of 2.2. Subtracting 11.7 sec. for
        bare machine time and 31.5 for CP/67 time, a ratio for WATFOR less
        job scheduler time was 1.5.

        I hand built the OS MFT system with careful ordering of
        cards in the stage-two sysgen to optimize placement of data sets,
        and members in SYS1.LINKLIB and SYS1.SVCLIB.

                            MODIFIED CP/67

OS run with one other user. The other user was not active, was just
available to control amount of core used by OS. The following table
gives core available to OS, execution time and execution time ratio
for the 25 FORTG compiles.

CORE (pages)    OS with Hasp            OS w/o HASP

104             1.35 (435 sec)
 94             1.37 (445 sec)
 74             1.38 (450 sec)          1.49 (480 sec)
 64             1.89 (610 sec)          1.49 (480 sec)
 54             2.32 (750 sec)          1.81 (585 sec)
 44             4.53 (1450 sec)         1.96 (630 sec)

-- 
Anne & Lynn Wheeler   | ly...@garlic.com -  http://www.garlic.com/~lynn/