purepath breakdown explanation
Hello,
I don't understand the purepath detail times,
we are running an application on a 8 CPU server, as you can see
- the response time is 14 833.59 ms
- the exec sum is 285 319.24 ms
as we have 8 CPU, we can compute
Exec Sum / CPU:= 285 319 / 8 = 35 665 ms
so it means that is all the 8 CPU where used at 100%, the response time should be 35 685 ms,and more in case of not 100%.
But as we can see the response time is 14 833.
So how are computed those numbers ?
regards.
Pierre
Here the details:
Please have a look at the following forum post and let me know if this answers your question: Understanding Purepath Breakdown
Hi, Andreas, it doesn't reply to my answer,
could you have a look on what I describe above and explain me your interpretation.
Regards.
Pierre
I am sorry that I "blindely" linked to the other blog post as it sounded very simliar from the headline of your question.
Is it possible that your PurePath is using lots of asynchronous activites, e.g: background threads? The Total Exec Sum could therefore be higher as we sum up the execution time of all parallel executed code. Here is a schematic example
/MyPurePath: Response Time = 1s, Total Exec Time = 1.4s
-> Async Thread #1: 700ms
-> Async Thread #2: 500ms
-> Async Thread #3: 200ms
The PurePath will show you whether you have asynchronous activity.
no problem Andreas 
But my question is not strictly about the fact that total exec is higher than response time,
It is about the fact that if we divide the total exec timee by the number of CPU, we have a number higher than the response time.
We are running an application on a 8 CPU server, and the exec sum is 285 319.24 ms. So basically we can compute that if all processors were 100% busy on it the response time should be 285 319.24 / 8 = 35 665 ms, or more if all the processor where not busy at 100 %.
But what we can see is the response time computed by Dynatrace is 14 833.59 ms.
So Dynatrace compute a response time two times below what the response time I compute, why ?
regards
Any chance you can export the purepath and send it over to me?
find the pp in attachment
Hi anynews ?
Regards.
Pierre
Thanks for reminding me about this - sometimes I loose track of all the forum entries I am working on 
So - it seems that you have a lot of background threads in your PurePath -> check out the Thread Column that you can make visibile in the PurePath Tree. You also see that you have a lot of wait time (85%). This means that most of the Total Exec Time is actually time that threads waited on other threads. Thats why it is possible that the Total Exec time is much higher than what you calculated.
Does this make sense?
