"Eric Thomas (Heidelberg Sc. Center)" <ERIC@DHDIBM1>
Wed, 22 Apr 1987 17:16 ESZ
|
There exists an IBM internal use only program on VNET which speeds up
DMSFREx calls. It is of course not available to BITNET/EARN people and if I
knew how it worked, I would not be allowed to explain it :-) I have been able
to play a little with it though, and it seems to be able to speed up execs by
-10% to 20% of execution time. Yes, -10%, in some cases it makes the program
run SLOWER than with the standard DMSFRE. The reason is obvious: if the
program is only issuing requests that can be served by the standard DMSFRE
only, it has to transfer control to DMSFRE and all that you get is the extra
overhead involved with the tests performed by the accelerator.
Anyway I was impressed by the improvement and decided to write my own -- an
EARN/BITNET internal use only one :-) I don't have the source of the IBM
program and have no idea of how it works, but I probably used a different
algorithm since the performance savings are usually different for a given
exec. My tests showed it to be generally faster than the IBM one, but in
several cases it was the opposite, especially for long execution times. I
would like to provide it as an optional facility with the next release of
LISTSERV, ie YOU decide whether you run it or not. I have strictly no idea of
how much CPU it may save you on a 'live' situation, and I cannot swear that it
will not end up in an addressing exception after working fine for 2-3 hours
(it's active on my virtual machine as I type these lines though :-) ). I would
therefore be very interested to find volunteers for beta-testing, especially
as I don't have time to test it extensively myself. The thing is one little
MODULE called KK (temp work name), which must be invoked ONCE (without being
NUCXLOADed or anything like that -- just type 'KK') and will remain active
until the next IPL CMS. You cannot terminate it without re-IPLing, mainly
because I'm too lazy to write the corresponding code :-) That's all you have
to know to test it. Please send requests to --> ERIC@FRECP11 <-- only.
Eric
|
|
|