Brian Peterson wrote:
The way I've always understood this is that SDSF schedules an SRB into the
target address space to get spool data in buffers.
Not in any supported release. (Specifically, not since z/OS 1.2.)
The difference between "S" (SDSF Browse) and the "SB"/"SE" (ISPF
Browse/Edit) line commands is that with the latter commands, all the data
is probably fetched up front. With "S", SDSF gets the data only when you
need it, as you need it. If you never scroll down to the bottom of the
data, SDSF never needs to get the data from the target address space.
Further, the SRB that SDSF schedules to the target address space does not
force the job to swap in. This means that if the low priority job happens
to be swapped out, the SRB won't run. SDSF designers don't want to give a
low priority job a "benefit" (forcing the system to swap it in) just to
view the in-memory spool data.
SDSF designers really have nothing at all to do with this. In z/OS 1.4
and z/OS 1.7 (the environments described by the OP), a JES2 service is
employed to read the outstanding spool buffers from an executing job.
That JES2 service schedules a preemptable SRB into the subject job's
address space. (You may wish to review APAR OA04704 for some history of
and at least one complaint about the behavior of this JES2 service.)
Dispatching the SRB will cause a swap-in of the target address space if
it is swapped out.
Finally, I have always understood that the SRB "times out" after 10
seconds. Thus, the delay. If the job is swapped in, the SRB will
run "instantly", but if swapped out, the SRB sits and waits until it times
out.
I've never heard of such a time-out. However, if it exists, it will
most-likely be implemented inside the JES2 service and not directly by
its callers.
--
Edward E Jaffe
Phoenix Software International, Inc
5200 W Century Blvd, Suite 800
Los Angeles, CA 90045
310-338-0400 x318
[EMAIL PROTECTED]
http://www.phoenixsoftware.com/
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