Re: Modifying Hit Ration and Object Size

From: Alex Rousskov (rousskov@measurement-factory.com)
Date: Wed Oct 10 2001 - 15:43:14 MDT


On Wed, 10 Oct 2001, Washington, Crystal wrote:

> I am attempting to run some investigative Polygraph test runs on
> our servers using 2.5.4. I was asked to run each test with
> different hit ratios and various object sizes. What are the
> simplest methods of changing these two parameters

To modify offered hit ratio, change recurrence ratio of your Robots:
 http://www.web-polygraph.org/docs/reference/pgl/types.html#type:docs/reference/pgl/types/Robot

To modify object sizes, adjust the size distributions of Content
objects used by your Servers:
 http://www.web-polygraph.org/docs/reference/pgl/types.html#type:docs/reference/pgl/types/Server
 http://www.web-polygraph.org/docs/reference/pgl/types.html#type:docs/reference/pgl/types/Content

Warning: PGL has no pointers, references, or ``pass by name''
parameters. A fresh copy of an object is created every time an object
is passed to a function or is assigned. Remember this fact when you
modify an object copies of which were already used elsewhere (your
changes will not be propagated to old copies)!

The above caveat applies when you change sizes of objects that are
embedded into container objects. For example,

  // wrong:
    cntHtml.may_contain = [ cntImage ];
    ...
    cntImage.size = exp(4KB);
    // now cntHtml uses "old" cntImage and Polygraph will complain

  // correct:
    cntHtml.may_contain = [ cntImage ];
    ...
    cntImage.size = exp(4KB);
    // reset to bring cntHtml in sync
    cntHtml.may_contain = [ cntImage ];

> and in which files would they need to be changed?

The files that need to be modified depend on the base workload you are
going to use. For example, if you want to use PolyMix-3, then merge
workloads/polymix-3.pg and workloads/include/polymix-3-guts.pg files
and then modify the resulting file.

No matter how tempting it may be, do not modify files in the include/
subdirectory as they are shared by many standard workloads.

Alex.



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