Re: Object Size

From: Alex Rousskov (rousskov@ircache.net)
Date: Mon May 15 2000 - 12:32:11 MDT


On Mon, 15 May 2000, Tim Eads wrote:

> How can I adjust object size in the Polymix-2 test?

Object sizes are defined via the "content" field:

    S.contents = [ cntImage: 65%, cntHTML: 15%, cntDownload: 0.5%, ... ]

where cntImage, cntHTML, cntDownload, and other content objects are
defined in workloads/include/contents.pg, included from polymix-2.pg.
For example, here is the cntImage definition:

        Content cntImage = {
                kind = "image";
                obj_life_cycle = StaticLifeCycle;
                size = exp(4.5KB);
                cachable = 80%;
        };

As you can see, "images" have exponentially distributed sizes with 4.5KB
mean.

> What is the default size and range?

I think that the final size mix used by PolyMix-2 cannot be described
using a single well-known distribution as it is a combination of very
different distributions (the same applies to the real traffic, I guess).
You can get the actual size distribution and max/min values from
Polygraph logs or reports. For example, the last bake-off reports
usually show a maximum file size of 3 - 4MB:
        http://polygraph.ircache.net/Results/bakeoff-2/polyrep/

For private tests, you are free to change the settings to address your
needs. For example, you can make all objects to have the same
distribution, even a "constant" one. Keep in mind that HTTP headers and
low level protocol overheads are not accounted for in the PGL
configuration.

HTH,

Alex.



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