Re: content distribution in polymix-4 - some confusion

On Sun, 4 Sep 2005, Serge Ayoun wrote:

> It is written at
> http://www.measurement-factory.com/results/public/cacheoff/N04/report.by
> -alph.html#Sec:Polygraph that polymix-4 uses the following statistic:
>
>
>
> Images:            65%      4.5KB size
> HTML:              15%      8.5KB
> Download:           0.5%  300KB
> Other:             19.5%   25KB
>
> Average of these is: A=10.575KB
>
> Also 85% are regular request and 15% are IMS. Among IMS, 66% requires
> complete response.
>
> So calculating the final expected average response size, we should get:
>
> A*0.85 + 0*.15*.33+ A*.15*.66 = 10KB
>
> However in "Reply size" section, average size is said to be 6.8KB. How
> is it possible?

Besides 304 responses to IMS requests (10%), there are several other 
factors that decrease mean response size compared to the mean object 
size. First of all, PolyMix-4 has a realistic byte hit ratio 
simulation model (the PopModel::bhr_discrimination parameter), where 
smaller objects are more popular than large ones. This leads to byte 
hit ratio being smaller than object/document hit ratio, an important 
characteristic of real traffic that earlier workloads were not able to 
mimic.

There are also bodyless HEAD responses and aborted responses (0.2%).

HTH,

Alex.