Take the 2-minute tour ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

I want to model the server under load.

I'm using following assumptions:

  • The server serves only one request at a time, and all requests take him exactly 100ms to process.
  • All requests that came while server was processing another request are placed into unlimited queue, and the processed in FIFO order.
  • Load is generated by "users", which make a request, wait for it to be served, the wait 5-15s(with flat distribution) before making next request.

The parameter I am most interested in is mean time of user waiting for his request. Ideally, I want to find a function like f(n), where n is number of users, and f(n) - is mean waiting time.

Modeling this for n=1 is easy - (f(1)=0.1), as it is for two users: the probability of second user making request while first user is being served is 0.01, so f(2) = 0.99*0.1 + 0.01*0.15 = 100,5ms.

But I'm stuck when I try to model more users.

Any suggestions?

share|improve this question
    
So you computed the value of f(2)? You could include the value you found. –  Did Aug 16 '11 at 10:58
    
@Didier Piau - included the result. –  Rogach Aug 16 '11 at 11:08
    
Thanks. You write the probability of second user making request while first user is being served is 0.01, why is that so? –  Did Aug 16 '11 at 11:17
    
@Didier Piau - Users are making requests each 5-15 seconds, so the average will be 10s between requests. So the probability is 0.1/10 = 0.01. Oh, but wait, mean time between requests depends on mean time to serve the request... And so here come the problems. –  Rogach Aug 16 '11 at 11:54

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.