RE: content distribution in polymix-4 - some confusion

Thanks Alex for your reply.
Still it is not clear to me how 6.8KB is achieved?

You said that 10% of the requests are IMS with 304 responses. This means
that my equation below needs some correction:

         "IMS - 200"
A*0.85 + A*.15*.33 = 9.5KB

If HEAD requests are 0.2% they do not impact the total average size.
Also since the average is measured at client side I do not see how byte
hit ratio has any effect on the total avg size? Smaller object may be
more popular, they still have an average which is fixed by the
image/html/download/other object statistic.

Thanks,
Serge

-----Original Message-----
From: Alex Rousskov [mailto:[email protected]] 
Sent: Sunday, September 04, 2005 7:02 PM
To: Serge Ayoun
Cc: users-mN9fGWdlm5pku/f+YMZH/di2O/[email protected]
Subject: 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.