RE: WRKSBMJOB, WRKUSRJOB slug-like

FYI, you don't have to have a lot of jobs hanging around.  The job tables
are also called the "work control block table" or WCBT.  Each entry is
associated with a single job and is called a "work control block table
entry" or WCBTE.  At V3R1 and before, there was no index to the active
WCBTE.  This could be true at V3R2 but I don't know.  If you wanted to
discover all the jobson the machine, you had to read the entire table.  I
think that it was at V3R1, some clever person in the lab decided that the
paging technique used to bring in the pages of the WCBT pushed out too much
non-WCBT stuff so they changed the technique to something called "exchange
bring".  This dramatically reduces the memory footprint but also eliminates
prefetching and forces lots of faulting.  I think that I remember a PTF to
fix this.   During Common in Austin Texas right after V3R1 was released, I
had lunch with one of the AS/400 performance "icons" and we chatted about
this.  I had spotted it because someone on some mailing list brought it up
so I went and did a test while running SMTRACE.  It was just pathetic.

The job commands take a long time because the machine is reading the entire
WCBT.  There is no WCBTE index like there is on RISC.  If the WCBT was EVER
very large, the system might still read it all.  Compressing or rebuilding
the table means you read less stuff so it goes faster.  Compress or rebuild
and look for PTFs.

I'm sure glad that Alexey and Eric remember this stuff, I had completely
forgotten about the compress data area.

Richard Jackson
mailto:richardjackson@richardjackson.net
http://www.richardjacksonltd.com
Voice: 1 (303) 808-8058
Fax:   1 (303) 663-4325

-|-----Original Message-----
-|From: owner-midrange-l@midrange.com
-|[mailto:owner-midrange-l@midrange.com]On Behalf Of
-|eric.delong@pmsi-services.com
-|Sent: Friday, September 29, 2000 5:43 AM
-|To: MIDRANGE-L@midrange.com
-|Subject: Re: WRKSBMJOB, WRKUSRJOB slug-like
-|
-|
-|
-|     Dan, do you have a large number of jobs hanging around with spool
-|     files? If your job tables have been extended, you will see very
-|     long waits indeed on the "job" commands.
-|
-|     Alexi responded to this issue with the following:
-|
-|> WRKxxJOB commands work by sequentially scanning WCBT (Work Control
-|> Block
-|> Table - job control structures on AS/400). If it takes a lot of time,
-|> it
-|> indicates that WCBT is heavily fragmented.
-|> Two things can be done: compress WCBT or force WCBT recreation.
-|> To compress WCBT:
-|>  -   create data area:
-|>           CRTDTAARA DTAARA(QSYS/QWCBTCMPTB) TYPE(*CHAR) LEN(1)
-|>
-|>      The following command will then turn on the compression of the
-|> WCBT
-|> during the IPL:
-|>
-|>           CHGDTAARA DTAARA(QSYS/QWCBTCMPTB) VALUE('1')
-|>
-|>      The following command will then turn off the compression of the
-|> WCBT
-|> during the IPL:
-|>
-|>           CHGDTAARA DTAARA(QSYS/QWCBTCMPTB) VALUE('0')
-|>
-|> To force WCBT recreation, perform manual IPL from system console, and
-|> on
-|> one of the menus you can request WCBT recreation.
-|>  It will remove all jobs from system, including all spool files.
-|> Two system values, which control WCBT allocation are QTOTJOB (initial
-|> allocation) and QADLTOTJOB (increment).
-|>
-|> Best regards
-|>     Alexey Pytel
-|
-|hth
-|eric.delong@pmsi-services.com
-|
-|
-|______________________________ Reply Separator
-|_________________________________
-|Subject: WRKSBMJOB, WRKUSRJOB slug-like
-|Author:  <MIDRANGE-L@midrange.com> at INET_WACO
-|Date:    9/28/00 5:11 PM
-|
-|
-|Good grief!  WRKSBMJOB & WRKUSRJOB are absolutely slug-like on
-|this V3R2 system.
-| It can take up to 30 seconds to get a response, everything else
-|(i.e., WRKSPLF,
-|WRKACTJOB) is at or near sub-second response.  This on a system
-|where the CPU
-|usage is 8.2% for a two minute interval (right now).  Is this a
-|V3R2 issue?
-|
-|I recall getting 2- or 3-second response with WRKSBMJOB even on
-|some RISC boxes,
-|and had resorted to using WRKUSRJOB JOBTYPE(*BATCH) to get the subsecond
-|response.  Either way, on this V3R2 box, it's a painful wait for
-|someone who's
-|used to getting it FAST.
-|
-|Anything I can do to improve on this?  Cleanup of some sort?
-|
-|Dan Bale
-|IT - AS/400
-|Handleman Company
-|248-362-4400  Ext. 4952
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