On 2014-01-20 04:38, John Blythe Reid wrote:
I just wanted to sound people out about converting a dataspace to a common
area above the bar. The main interest is the effect it would have on CPU
usage.
To put it into context, the dataspace is used for a set of tables which are
used by the application programs. There are around eight thousand tables
currently occupying about a gigabyte of virtual storage. This is a large
installation with excess of 700 million transactions per month plus a heavy
batch load. The application programs make extensive use of these tables.
Whenever an application program needs an element of one of the tables it
calls a standard assembler module which uses access register mode to search
the table in the dataspace and then returns the requested element to the
application program.
If the set of tables were placed above the bar then access register mode
would not be needed as the tables would be directly addressable in 64 bit
addressing mode.
It all seems much simpler so, at first sight, it would be expected to use
less CPU. A reduction in CPU would be the main justification for doing the
conversion.
I would be very interested on anyone's opinion on this subject.
Regards,
John.
I did some tests of a very similar scenario, expecting to see a
significant performance gain. The actual results showed a reduction in
CPU usage of about 1-2%. We decided that the gain was small enough that
we were better off continuing to enjoy the data isolation provided by
the data space.
--
Regards, Gord Tomlin
Action Software International
(a division of Mazda Computer Corporation)
Tel: (905) 470-7113, Fax: (905) 470-6507
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