LoadRunner: PACING Calculation

How to calculate Pacing in LoadRunner?

D = Duration of the test (test window/time frame)

B = Baseline time (total time taken by 1 Vuser to complete 1 whole iteration)

T = Total amount of Think time in the script

I = Expected/Target iteration

R = Residual time of the test window.

 

R = (D - (T + B)*I)

P = Pacing interval

Dividing the residual time by target iteration gives pacing interval

Hence: P = R/I

D is pacing time.

(T + B)*I represent the duration of a scenario and P is the waiting time before the next scenario

Calculating Pacing Time/Think Time to achieve 50 TPS with an average response time of 0.5 seconds with total of 100 Users

Let us start with calculating total number of transactions in an hour.

1 sec = 50 transactions

Transactions per hour by 100 users =50 TPS *3600 sec = 180000 Transactions

We have total number of users given as 100. Let us see how to calculate how many transactions each user will perform.

Total Number of Users = 100

Each User will perform 180000/100=1800 transactions/hour

Since, every transaction is taking on an average 0.5 seconds, let us see how much time is required to complete the each user transactions.

To complete 1800 transactions, it will take 1800*0.5 = 15 minutes

So now, let us see how much think-time is required to complete the required number transactions per User in an hour.

1800 transactions will complete in 15 minutes

Hence, 45 minutes of think time is required in between 1800 transactions (i.e. 45*60 = 2700 seconds of think time required in between 1800 transactions (per user))

2700 seconds required for  1800 transactions

x = 1.5 seconds think time need to include

Let us see how much time is required to complete each iteration.

Total time required to complete each Iteration = x + 0.5 seconds = 1.5 + 0.5 = 2 seconds

Verification: Let us verify if our above calculation is correct.

Total time = 1800 * 2 = 3600 seconds = 1 Hr

So, Each User will perform 1800 transactions where we will provide 2 seconds for each Iteration to complete.