Sorry for the slightly off-topic question, but how come this persons posts
are always so complicated to work through with all of the pieces and URL
links? Is it the function of how they are posting (i.e. perhaps online with
certain options), or is this a manual effort?

I'm hoping to not spark a long debate. I'm hoping it's just a "one or the
other" answer.

David Logan

-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf
Of Anne & Lynn Wheeler
Sent: Tuesday, January 22, 2008 7:18 AM
To: IBM-MAIN@BAMA.UA.EDU
Subject: Re: How does ATTACH pass address of ECB to child?

The following message is a courtesy copy of an article
that has been posted to bit.listserv.ibm-main,alt.folklore.computers as
well.

[EMAIL PROTECTED] (Peter Relson) writes:
> You can be certain that POST will always support the CS quick-post
protocol
> and the LOCAL LOCK.

re:
http://www.garlic.com/~lynn/2008b.html#50 How does ATTACH pass address of
ECB to child?

as stated in the above post ... the principles of operation wording is
from over 35yrs ago ... charlie had invented the compare&swap
instruction at the science center while doing fine-grain lock for cp67
... and the pok favorite son operating system people had rejected it
... i.e. the test&set was more than adequate for the global kernel
spin-lock multiprocessor support from 360 ... mention of global
spin-lock
http://www.garlic.com/~lynn/2008b.html#58 How does ATTACH pass address of
ECB to child?

the challenge given the science center
http://www.garlic.com/~lynn/subtopic.html#545tech

was come up with example uses for compare&swap instruction ... other than
(multiprocessor) locking operation ... some discussion
http://www.garlic.com/~lynn/2008b.html#58 How does ATTACH pass address of
ECB to child?

i.e. the compare&swap instruction can be used for atomic updates for
whole class of operations w/o requiring "locking" operation (which would
typically also require supervisor call into the kernel to have
uninterruptable operation ... as a means of simulating atomic update).
as mentioned in the above analogy with dbms financial transaction and
optimistic operation ... that avoids lock ... if certain original
conditions continue to hold when the transaction changes are actually
made permanent.

so the wording in the principles of operation was from the stand-point
that the pok favorite son operating system people still had to
understand the implications of how compare&swap instruction could be
used ... and then actually have the changes permeate their
implementation.

my familiarity with cp67 dates back to when 3 people from the science
center
http://www.garlic.com/~lynn/subtopic.html#545tech
came out to install cp67 at the univ the last week of jan68 (40yrs ago
this week)

one might claim that maybe that its time to update that 35+yr old
perspective in the principles of operation compare&swap writeup.

A.6 Multiprogramming and Multiprocessing Examples
http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/DZ9ZR003/A.6?SHEL
F=DZ9ZBK03&DT=20040504121320

other posts in this thread:
http://www.garlic.com/~lynn/2008b.html#31 How does ATTACH pass address of
ECB to child?
http://www.garlic.com/~lynn/2008b.html#47 How does ATTACH pass address of
ECB to child?
http://www.garlic.com/~lynn/2008b.html#48 How does ATTACH pass address of
ECB to child?
http://www.garlic.com/~lynn/2008b.html#51 How does ATTACH pass address of
ECB to child?
http://www.garlic.com/~lynn/2008b.html#60 How does ATTACH pass address of
ECB to child?

for some topic drift ... related to dbms operation ... misc. posts about
the original relational/sql project
http://www.garlic.com/~lynn/subtopic.html#systemr

and transcriptions of '95 SQL reunion
http://www.mcjones.org/System_R/SQL_Reunion_95/index.html

there is mention of compare&swap in the discussion about use for
"locking"
http://www.mcjones.org/System_R/SQL_Reunion_95/sqlr95-Shoot-ou.html#Index311
in this session:
http://www.mcjones.org/System_R/SQL_Reunion_95/sqlr95-Shoot-ou.html

however, the speculation about the origin of compare&swap instruction
was wrong (i.e. compare&swap was chosen because CAS are charlie's
initials).

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