David_Dalgaard_
Nimbostratus
Jul 12, 2012

# iRule Performance

Hi folks

We are just starting to look into iRules and I am trying to figure out what performance impact iRules will have. I googled around and found the following thread:

https://devcentral.f5.com/Community/GroupDetails/tabid/1082223/asg/50/aft/3650/showtab/groupforums/Default.aspx

UnRuleY gives a great explanation, but this explanation falls apart when I try to use the iRule Runtime Calculator.

I have an iRule where average CPU cycles is 170000. The box it is deployed on is a 6900 (2 CPUs, 2 cores @ 2,2GHz). As far as I can understand iRules are fully compatible with CMP, which means that I could roughly multiply the clock by four, but just to make it simple let us calculate with 1 core only.

Average CPU cycles * executions per second / clock frequence = 170,000 * 100 / 2,200,000,000 = 0.007727 % (this number makes great sense to me, but I might have misunderstood something in regard to CPU cycles/clock frequence)

However, when I use the calculator and put 170000 under Event_1, I get the above results - but I don't think it's multiplied by 100.....

Can anyone tell me if unRuleY/I made a calculation error or is it the calculator that is wrong??

Thanks!

### 4 Replies

• However, when I use the calculator and put 170000 under Event_1, I get the above results - but I don't think it's multiplied by 100.....100 is from % (format cells > number > percentage), isn't it??
• Thanks for you reply Nitass, however, I am not sure I follow you? Where should the formatting be different?
• Average CPU cycles * executions per second / clock frequence = 170,000 * 100 / 2,200,000,000 = 0.007727 %i understand you ask why irule runtime calculator result is 0.007727 % same as your above calculation but you do not think there is *100 in the runtime calculator, don't you?

if so, i understand *100 in the runtime calculator is percentage format cells (format cells > number > percentage in excel file).

or am i lost?? :-)
• Well, the standard formatting is in percentage, but if I change to decimals I get the number I expect.

I just think its weird that the formatting is wrong. I guess other have used this doc before me..

Can anyone verify that my result is the correct? 0.007727 % for 100 executions per sec?