Powerhouse Quiz takes 60%+ CPU in EXEC mode

[Hamilton, Allison]

If your files are poorly optimized, or quite fragmented, or your disk close
to full, you will see very high CPU usage when trying to access the files
because RMS is having to work so hard to get the information you request.  I
believe that you are correct in that this would show up as EXEC mode.  My
experience is that once a disk hits 80% full it's performance starts to
drop, and once it hits 90% full you might as well go home because it'll
spend it's life trashing.  If the files are fragmented then you can correct
that by using a disk defragger or you can do a backup/restore of the disk to
restructure the files in a more contiguous manner. (You can see
fragmentation using anal/rms or a disk defragger report.)  I would use the
defragger since there seem to be ones that work safely out there now.  In a
previous company, we used to run the defragger in the background every
night.  It would shuffle all the files that weren't being used around to try
to make them more contiguous.  Did a pretty good job at keeping us
functional, without having to take disks offline to do backup and restores.

If your files have not been optimized and you created them through
PowerHouse, I would strongly suggest that you read the RMS manuals and
optimize them. PowerHouse takes very general default options when the files
are created, which are not appropriate for large or high volume files, but
that's all it can do at that point.  I can't remember the exact sequence,
but first you do an anal/rms/fdl of the file to get an fdl of the current
file.  Then you run edit/fdl/anal  in some format, but I can't remember the
exact commands, to optimize the file based on the data in it, and the
loading characteristics.  Then use a convert/fdl to create a new, optimized
file and load it. You can edit/fdl interactively to split file areas across
disks, and other 'clever' optimization techniques if you know what you are
doing. (I think there was an article on how to do this in a SupportLink.)

For new files, if you know the load characteristics (volume, data entry
patterns...) you can do an interactive edit/fdl after generating the fdl to
create an optimized file from the start, before data is loaded.  It is often
good for performance to re-optimize the file at regular intervals as data is
loaded, because your original load characteristics may not have been
accurate.  This is true of all files, not just those used by PowerHouse.  It
is RMS, not PH that has problems dealing with poorly optimized files.  We
optimized our large or active files for all applications, written in all
languages.
Allison Hamilton

> ----------
> From: 	Chris Sharman[SMTP:Chris.Sharman@ccagroup.co.uk]
> Sent: 	Wednesday, February 24, 1999 3:46 AM
> To: 	john.webster@cdp.co.nz
> Cc: 	Chris.Sharman@ccagroup.co.uk; powerh-l@lists.swau.edu
> Subject: 	RE: Powerhouse Quiz takes 60%+ CPU in EXEC mode
> 
> >Check the number of defines; if its more than a dozen or so, check the
> select
> >statement; if you are selecting relatively few records from a large
> database
> >remember that defines are evaluated BEFORE the select statement... then
> split
> >the report into two passes - one to select the data required and write it
> to a
> >subfile, the second to pick up the subfile, link to data not needed for
> >selection, and evaluate the defines.
> >
> >IMHO this is one of the major ways of increasing Quiz/QTP performance.
> 
> Interesting tip, thanks. I'd have thought Cognos ought to address that
> one, in
> the same way they don't read more records than necessary before rejecting
> a
> record complex.
> 
> But everyone's missing part of my point: Quiz & QTP may be CPU hungry, but
> they
> run in USER mode (I hope). I'm seeing a big hit in EXEC mode, and
> relatively
> modest USER mode demand. This suggests it's RMS itself being CPU bound,
> which
> I find very difficult to fathom.
> ______________________________________________________________________
> Chris Sharman			Chris.Sharman@CCAgroup.co.uk
> CCA Stationery Ltd, Eastway, Fulwood, Preston, Lancashire, PR2 9WS.
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