Long response times occur on the SAP GUI although the transaction only has a short runtime in the SAP System. Other terms
Hourglass, performance Reason and Prerequisites
The response time on the SAP GUI is generally made up of the following parts:
1. Time within the SAP System
2. Time for the network transfer
3. Time for displaying on the front end
Calculating the time for the network transfer:
You can use the performance statistics of the SAP System to determine the time in the SAP System. This is approximately the sum of the values: " CPU time", "DB req time" and "Wait time". You can use transaction STAD to display the performance statistics records.
The time for the network transmission cannot be measured exactly. However, you can estimate it using the "FE net time" and "GUI time" statistics values. The "FE net time" is the time for the network transmission of the first request to the server and the last response back to the front end. The measurement of "FE net time" was incorrect (see note 679918).
If a dialog step contains additional round trips, these are measured separately as "GUI time". Therefore, the "GUI time" contains the network time as well as the display time on the front end for all round trips.
You can use the "GUI time" value as a first indicator to see whether a lot of time is consumed outside of the SAP System. If this value is much higher than the time in the SAP System (for example, by a factor of 10 or more), you can perform the time calculation for the network transmission described below. You can then distinguish between which time portion is accumulated in the network and which is accumulated on the PC front end. With the calculated network time, you are still able to differentiate between which time portion is caused by the available range of fluctuation and which is caused by the RTT round trip time.
If necessary, you can increase the range of fluctuation on which the RTT is usually determined by the type of network and the topology.
If the statistical values of the network (throughput and RTT round trip time) are known, you can determine the time for the network transmission using a calculation. If the network characteristics are not known, or to get real values of the network, you can also measure them using the niping SAP test program (see note 500235). With competing data traffic on the network, the measured values are subject to great fluctuations.
networktime = (no_of_bytes)/(throughput) + (no_of_round_trips)*(RTT)
From the performance statistics of the SAP System (transaction STAD), you get the no_of_bytes as a total of the "Terminal in-message" and Terminal out-message" values. The number of round trips consists of the "No. of roundtrips" value. You must increase this value by one because, from the point of view of the SAP GUI, it does not contain the first request and that last responses.
Example: Network values (for example)
Throughput: 6400 bytes/sec
This value corresponds approximately to a 64-kbits line (64000 bit/sec) without competing data traffic.
RTT round trip time: 200 msec = 0.2 sec
The following values result, for example, from the performance statistics:
"Terminal in-message": 25429 bytes
"Terminal out-message": 2717 bytes
This result in the total: 28146 bytes
"No. of roundtrips": 6
To get the number of round trips from the SAP GUI point of view, you still have to add one. That is, no_of_roundtrips = 6+1 = 7
networktime = (28146 bytes)/(6400 bytes/sec) + 7 * 0.2 sec
= 4.4 sec + 1,4 sec
= 5.8 sec
In this example, the time to be expected for the network transmission alone is therefore 5,8 seconds.
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