On Mon, 20 Sep 2021 16:26:59 -0500, Hobart Spitz wrote:
> ...
>For those who don't know, in the typical case, a record passes through all
>possible stages before the next record begins the same trip. Each record
>stays in the working page set, at least partially, during the entire time.
>Parts that are referenced have a good chance of staying cache resident
>between stages.
>
I'm guessing the atypical case is a stage such as FANOUT which necessarily
copies the data.
> ... My best guess is that Pipes, in this analogy, would have only
>5%-15% of the narrow openings as an equivalent UNIX piping command, meaning
>that the data (sand) would flow 85-95% faster in the Pipes "hourglass".
> ...
I suspect the cost of moving data is overwhelmed by the cost of process
switching. And z/OS UNIX is probably the worst of all UNIXem because
its design hasn't been optimized for process switching.
(I wonder whether nowadays z/OS creates more address spaces for job
step initiation or for fork(). I'm confident that the design remains
optimized for the former, regardless.)
But remember that nowadays silicon is ofteen cheaper than carbon.
With POSIX pipes I can:
407 $ ls | wc
2 2 17
(got it right the first time. A useless example, admittedly.)
What would that look like using JCL an Batchpipes, replacing "ls"
with LISTDS and "wc" with (utility of your chiice)? (I wouln't get it
right the first time.)
-- gil
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