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Al, Please don't take this personally, but a certain amount of skepticism is warranted for most of the folklore about performance on an AS/400. I understand what your Instructor was trying to convey, and technically he may be correct, but practically I just don't believe that there are any performance problems with qualified program calls. Further, I have a hard time believing that even if there were a difference, it would be large enough to matter. I guess the only way to tell for sure is to run a test.... <Several hours later> OK, I'm done. I just ran a test on one of our /400's that would seem to indicates that your instructor's information is incorrect, outdated, or irrelevant. The tests indicate that an unqualified call appears to take a little longer than a qualified call. See below for the test results. MacWheel99@aol.com wrote: > > From: DBale@lear.com (Bale, Dan) > > > > Wow. Is this documented, Al? > > Referring to my remarks about qualifying vs. library list > > John Earl also challenged what I thought I had learned in IBM school. > > I could not find explicit clarification in any of my manuals, so I e-mailed > question to IBM school asking what I had absorbed incorrectly on this topic & > here is the reply from one of my IBM professors: > > QUOTE > > Al, > > When access is requested to an object and *LIBL is specified for the object > the library list information is used to check authority for the LIBRARY. If a > qualified name is specified, the authority for the LIBRARY is specifically > checked, even if the library is included in the user's library list. > > *LIBL has the system establishing LIBRARY authorities for the libs in the > list. > Subsequent LIBRARY authority lookups are not going to be done UNLESS > the lib_name/obj_name qualification is used. The system will lookup the > authority the user has to the library every time a qualified reference is > used. > > That's just for the library. The system then has to handle the security > for the object itself. Hope that helps. > > Eric J. Jackson > Sr. Education Specialist - AS/400 > IBM Learning Services > 330 N. Wabash, 4th floor > Chicago, IL 60611 > > UNQUOTE > > My primary interest is in correcting any misconceptions that I had had. > My conclusion from this is that my prior statement was a simplification, but > that overall it is true that there is more security checking by qualification > than by library list. One thing that is not clear to me is in the case of a > library with thousands of program objects ... including that in library list > might result in excess checking, also hurting performance. > > ie. our folks sign onto BPCS & they do not get the BPCS logo instantaneously, > because their library list is being heavily loaded with access to approx 20% > of the stuff in 12 Gig. That lag does not bother me yet. > > Al Macintyre ©¿© > http://www.cen-elec.com MIS Manager Programmer & Computer Janitor > +--- > | This is the Midrange System Mailing List! > | To submit a new message, send your mail to MIDRANGE-L@midrange.com. > | To subscribe to this list send email to MIDRANGE-L-SUB@midrange.com. > | To unsubscribe from this list send email to MIDRANGE-L-UNSUB@midrange.com. > | Questions should be directed to the list owner/operator: david@midrange.com > +--- For this test I created a program called "A" and put it in library "JOHN". Program "A" has a single statement: C EVAL *INLR = *ON By ending the program with LR on after each call, I am causing a security lookup with each call to the program, rather than reusing an open version of the program. Then I created two CL programs (TEST1 and TEST2) that call program "A" a variable number of times. The variable number is passed into the program using the parameter "&Iter". Program "TEST1” did an unqualified call (CALL A), and program "TEST2" a qualified call ( CALL JOHN/A ). Here is the code for the unqualified call: 0001.00 PGM &Iter 0002.00 0003.00 DCL &Count *Dec ( 15 5 ) 0004.00 DCL &EndMsg *Char 80 0005.00 DCL &Iter *Dec ( 15 5 ) 0006.00 DCL &Iter_Char *Char 15 0007.00 DCL &StartMsg *Char 80 0008.00 0009.00 CHGVAR &Iter_Char &Iter 0010.00 CHGVAR &EndMsg ('End call of 1 unqualified program' *BCAT + 0011.00 &Iter_Char *BCAT 'times') 0012.00 CHGVAR &StartMsg ('Begin call of 1 unqualified program' *BCAT + 0013.00 &Iter_Char *BCAT 'times') 0014.00 SNDJRNE JRN( QAUDJRN ) TYPE( 'PT' ) ENTDTA( &StartMsg ) 0015.00 0016.00 LOOP: 0017.00 CHGVAR &Count ( &Count + 1 ) 0018.00 CALL A 0019.00 IF ( &Count *NE &Iter ) THEN( GOTO CMDLBL( LOOP )) 0020.00 0021.00 SNDJRNE JRN( QAUDJRN ) TYPE( 'PT' ) ENTDTA( &EndMsg ) 0022.00 0023.00 SNDMSG MSG( &EndMsg ) TOUSR(JOHN) 0024.00 ENDPGM The difference between "TEST1" and "TEST2" was that line 18 of "TEST2" looked like this: 0018.00 CALL JOHN/A and the journal entry messages were changed. Here is "TEST2": 0001.00 PGM &Iter 0002.00 0003.00 DCL &Count *Dec ( 15 5 ) 0004.00 DCL &EndMsg *Char 80 0005.00 DCL &Iter *Dec ( 15 5 ) 0006.00 DCL &Iter_Char *Char 15 0007.00 DCL &StartMsg *Char 80 0008.00 0009.00 CHGVAR &Iter_Char &Iter 0010.00 CHGVAR &EndMsg ('End call of 1 qualified program' *BCAT + 0011.00 &Iter_Char *BCAT 'times') 0012.00 CHGVAR &StartMsg ('Begin call of 1 qualified program' *BCAT + 0013.00 &Iter_Char *BCAT 'times') 0014.00 SNDJRNE JRN( QAUDJRN ) TYPE( 'PT' ) ENTDTA( &StartMsg ) 0015.00 0016.00 LOOP: 0017.00 CHGVAR &Count ( &Count + 1 ) 0018.00 CALL JOHN/A 0019.00 IF ( &Count *NE &Iter ) THEN( GOTO CMDLBL( LOOP )) 0020.00 0021.00 SNDJRNE JRN( QAUDJRN ) TYPE( 'PT' ) ENTDTA( &EndMsg ) 0022.00 0023.00 SNDMSG MSG( &EndMsg ) TOUSR(JOHN) 0024.00 ENDPGM The Library list for the job was as follows: LIBMSYS SYS PowerTech IBM System Library LUSRSYS SYS PowerTech User System Library QSYS SYS System Library QSYS2 SYS System Library for CPI's QHLPSYS SYS QUSRSYS SYS POWERLOCK PRD PowerLock Network Security Product Library QGPL USR QTEMP USR JOHN USR Programmer library for John Earl The tests were run under User Profile "JOHN" who has no special authorities. "JOHN" is a member of group "PROG" which has *JOBCTL and *SAVSYS special authorities. I ran three sets of tests. For each set I called programs TEST1 and TEST2 twice. The first time I passed a value of 10,000 to the programs and the second time I passed a value of 100,000 to the programs. Using the SNDJRNE commands allowed me to log the start and end time of these loops. The tests were run on a model 170 with 128MB of Memory and 8GB of disk. OS version is V4R3. There were no other active jobs other than my workstation during the tests, and I refrained from hitting any keys until the completion message appeared on my screen. The results were as follows: First Test Second Test Third Test UnQual Qualified UnQual Qualified UnQual Qualified 100000 14:09:29 14:05:42 22:23:59 22:38:04 23:20:43 23:33:29 Calls 14:13:30 14:09:08 22:27:51 22:41:27 23:24:54 23:36:52 Difference 0:04:01 0:03:26 0:03:52 0:03:23 0:04:11 0:03:23 10000 13:52:12 14:03:39 22:46:46 22:46:22 23:17:41 23:18:08 Calls 13:52:36 14:04:00 22:47:09 22:46:42 23:18:05 23:18:28 Difference 0:00:24 0:00:21 0:00:23 0:00:20 0:00:24 0:00:20 These tests indicate that their is slightly _better_ performance with a qualified call than with an unqualified call. So while the technical description that your instructor gave you may still be true, the actual effect on performance is the opposite of his predictions. But even if the results were reversed, one has to ask how important performance is in this circumstance? If 10,000 calls runs 3 - 4 seconds longer and 100,000 calls run anyhere from 29 - 48 seconds longer how many applications will really be slowed down by choosing one way over the other? If you've got an interactive app that refers to 3 or even 10 unqualified objects, will anyone notice that you didn't qualify them? If you have a batch job that refers to 250,000 unqualified objects and it runs 2 minutes longer, who will know? A good summary would be that this performance "issue", like many of the other performance legends that we carry forward from the days when machines were slow, only serves to distract us from the real task at hand (building sound applications). A secondary point is that whenever someone claims that one method performs better or worse than another, it ought to be really easy to test the claim on our own. All of this is of course, JMHO, and you're welcome to repeat the test on your own machine and tell us whether you get corroborating results. jte (Convalescing, with obviously too much time on his hands :) -- John Earl johnearl@400security.com The PowerTech Group 206-575-0711 PowerLock Network Security www.400security.com -- +--- | This is the Midrange System Mailing List! | To submit a new message, send your mail to MIDRANGE-L@midrange.com. | To subscribe to this list send email to MIDRANGE-L-SUB@midrange.com. | To unsubscribe from this list send email to MIDRANGE-L-UNSUB@midrange.com. | Questions should be directed to the list owner/operator: david@midrange.com +---
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