[comp.sys.mac.misc] Settings of cache-memory vs system performance

rdw89@ecs.soton.ac.uk (Williams RD) (03/07/91)

In <1991Mar6.141414.6567@nada.kth.se> ulfis@nada.kth.se (Anders Ulfheden) writes:


>When playing around with Speedometer for measuring system performance I have
>noticed that turning the cache memory ON, reduces the speed in some cases
>with a factor 2!

It seems to me that Speedometer ratings are not an 'absolute' quantity.
I have been conducting extensive tests on my IIsi with Speedometer,
because under certain circumstances the machine seems to slow down
to a crawl.  The effect of selecting a 256 greyscale monitor configuration
is not always as drastic as Speedometer reading postings from other
people would imply.

I would be very interested to know the REAL reasons for sudden slow
downs, especially on the IIsi.  Here are a few things that have affected
Speedometer ratings:

* Multifinder vrs Finder (obvious!)
* Under Multifinder, switch from Speedometer to another application,
  then back to Speedometer.  Often speeds up significantly.
* Under Finder or Multifinder, launch an application, then quit, then
  allow a screensaver (After Dark, say) cut in.  Then run Speedometer;
  this combination has (very frequently, though not ALWAYS) dramatically
  improved the 'Math' performance of my IIsi with FPU enabled.  A typical
  math performance would be 117, but after doing this, the math performance
  often leaps to 149 (complete with tinkling glass sound effect - gave me
  a bit of a suprise!).
* Restarting the computer with 256 greys, against starting with B&W
  and then selecting 256 greys.  Starting with 256 greys sometimes
  reduced math performance to 85, and CPU from 5.3 to 3.7.
* TURBO PASCAL.  Yes, I expect no-one else in the entire world is
  still using Turbo on the mac, but apart from not liking run sessions
  under multifinder (which the documentation hints at), even under
  Finder the application seems to completely destroy performance on
  the IIsi.  This problem remains even after quitting the application!

Any comments?

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Richard Williams,                                  |
Department of Electronics and Computer Science,    |
Southampton University,                            |  EMAIL ADDRESS:
Highfield,                                         |  rdw89@ecs.soton.ac.uk
Southampton.                                       |
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