Thursday, June 6, 2013

VUSER CALCULATIONS ?

Calculating How Many Maximum Number Of Users Required If We Need To Achieve 12K Transactions With SLA Of 5 Minutes

Total Number of Transactions to be completed = 12,000
Average Response Time = 5 Minutes

To avoid putting much load on the system I will add 5 Minutes so that to total time taken to complete one iteration will be 10 Minutes. This addition will include the thinktime between the each screen/transaction traverse.

Now, I know each iteration will take 10 Minutes to complete, hence in 60 Minutes only 6 transactions can be completed. i.e. 1 User will do 6 transactions in an hour.

Now how to calculate how many users are required to complete 12,000 transactions in an hour?
The calculation will be:
#Users Required = 12,000/6
= 2000 Users

This way we can find the number of users required if total throughput is provided with an average response time.

Hence to achieve 12,000 transactions I need 2000 Users with 5 minutes of thinktime in between the iterations with an average response time of 5 Minutes.

Hope this post helps you to come-up with a Workload Modelling Concept (a bit). Please do let me know if my assumptions are wrong.

3 comments:

VIJAY GUPTA said...

great explanation .Thanks for sharing the info.

Sindhu said...

Also we can calculate the total number of users using Little's Law

Little's Law

N = (Rt + Zt)* X

N = Number of users in the system
Rt = Response Time
Zt = Think Time
X = Throughput

Here X =12000 per Hr=12000/60 per min=200/min
Rt=5 min
Zt=5 min

N =(5+5)*200
=2000

Regards,
Sindhu

Malkesh Gupta said...

it is very simple-

TPS * Total time (Response time+ Think time) in sec to complete one iteration

Transaction in hr - 2000
Total time for itr - 600 in secs

users = TPS* Total time
users = (12000/3600)*60 = 2000

Cheers
Malkesh