Setting Performance Parameters (SAP Library - ITS Tuning and Troubleshooting Guide)

Setting Performance Parameters

Use

You use this procedure to set parameters in order to optimize performance.

Most parameters are defined during ITS setup, but you have to create some explicitly in the Windows NT registry. When they have been defined, you can change their values in ITS Administration.

The following table lists the parameters you can set to optimize performance and briefly describes each one:

Parameter	Description
CacheInvalidateHour	Hour of each day to clear cached module call results. This is a 24-hour clock! Use in conjunction with CacheInvalidateMinute. The default value is 0.
CacheInvalidateMinute	Number of minutes past the hour specified in CacheInvalidateHour to clear cached module call results. Use in conjunction with CacheInvalidateHour. The default value is 0.
CacheSize	Size of cache used to store data retrieved by module calls to the R/3 System. The cache size is defined during ITS setup, but you can use this parameter to change the value. The default value is is 2097152.
DiagCompression	Enables / disables compression of DIAG data between the ITS and the R/3 System. The DIAG protocol is used to transfer R/3 transaction screens to the ITS. During ITS setup, this parameter is undefined and therefore not visible in ITS Administration. The default is assumed to be 1 (compression of DIAG data enabled). To disable compression of DIAG data, you must set the following Windows NT registry value explicitly to 0: \HKEY_LOCAL_MACHINE\SOFTWARE\SAP\its\2.0\ <ITS instance>\Programs\AGate\DiagCompression You then see the parameter in ITS Administration.
IncAGates	Number of extra AGate processes for heavy loads. You use this parameter to specify the number of extra AGate processes that should be created when existing processes are heavily loaded. The value of this parameter can be no greater than the value of MaxAGates (see below). The default value is 1.
MaxAGates MinAGates	Maximum and minimum number of AGate processes per ITS instance. You should set the number of AGates to a value higher than 1 only if at least one of the following conditions applies: The number of sessions is higher than 400 The memory allocation per AGate is more than 2 GB Since starting an AGate process is an expensive operation, the minimum number of AGates should always be the same as the maximum number of AGates. Please also remember that if you have a dual host installation, you must make corresponding changes on the WGate side. If you change this value from 1 (single AGate process) to greater than 1 (multiple AGate processes) or from greater than 1 (multiple Agate processes) back to 1 (single AGate process), you must change the multiprocess parameter in the wgate.conf file manually to reflect this. Since multiprocess accepts only two values ( no for a single AGate process, yes for multiple AGate processes), you do not need to do anything if you change the value from greater than 1 to a different value greater than 1 . The default value is 1.
MaxCtxtSize MinCtxtSize	Maximum and minimum number of bytes used to store internal data during request processing. The parameters MaxCtxtSize and MinCtxtSize are new in ITS Release 4.6DC4. In earlier releases, the minimum and maximum context sizes were equal to the values specified by the MaxReqSize and MinReqSize parameters. The default value of MaxCtxtSize is 5242880. The default value of MinCtxtSize is 65536.
MaxHrnpSize MinHrnpSize	Maximum and minimum size in bytes of HRNP (HyperRelational Navigation Protocol) container used to store callback data relating to Drag&Relate from the R/3 System. The default value of MaxHrnpSize is 2097152. The default value of MinHrnpSize is 32768.
MaxInetSessionCtxtSize	Maximum size of the persistent context available to an ITS Flow Logic application. The persistent context is created only if a flow file in the application specifies persistent data. The default value is 4096.
MaxReqSize MinReqSize	Maximum and minimum number of bytes used to store request data received from the Web browser. You use these parameters to set the maximum and minimum memory requirement per session. Registry. Under Windows NT, the maximum size specified by MaxReqSize is reserved in the virtual address space, but only the minimum size specified by MinReqSize is actually used until more space is required. In some cases, you can reduce the default value of MaxReqSize. If, for example, you are not using the SAP GUI for HTML, you can reduce the size to as little as 0.5 MB. However, you should determine the optimum size for your own installation gradually through ongoing tuning. It is worth setting this parameter deliberately low in order to see what kind of error messages result. This also gives indicates what kind of value you need to set for your own installation. The default value of MaxReqSize is 5242880. The default value of MinReqSize is 65536.
MaxRespSize MinRespSize	Maximum and minumum number of bytes used to store response data sent to the Web browser. You use these parameters to set the maximum and minimum memory requirement for output. Registry. Under Windows NT, the maximum size specified by MaxRespSize is reserved in the virtual address space, but only the minimum size specified by MinRespSize is actually used until more space is required. The default value of MaxRespSize is 2097152. The default value is MinRespSize is 32768.
MaxRfcSize MinRfctSize	Maximum and minimum size in bytes of RFC container used to store callback data from the R/3 System. The default value of MaxRfcSize is 2097152. The default value of MinRfcSize is 32768.
MaxServiceContextSize	Size of internal buffer used to store service files. These files are automatically cached at runtime to improve performance. The default value is 4096.
MaxSessionContextSize	Maximum size of session context. The session context is initialized at the beginning of each request and is used to store data identified as persistent by the application. The session context is created only if the application specifies persistent data. The default value is 4096.
MaxSessions	Maximum number of sessions allowed. The default value is 400 (64 for a minimal configuration).
MaxWorkThreads MinWorkThreads	Maximum and minimum number of workthreads allowed. When the server starts, the ITS starts a fixed number of workthreads. You should choose values for these parameters that will support the maximum load that the server has to carry. If the number of workthreads remains low for a very long time, you should increase the number by changing the values of MaxWorkThreads and MinWorkThreads. Unless the load on the server is very unevenly distributed, both these values should be equal. If you are not sure what values to specify for these parameters, set MaxWorkThreads to twice the value of MinWorkThreads. Then, look at the load statistics log and determine the number of workthreads required from the maximum number of workthreads used within the observation period. Since the ITS allocates memory for each workthread and session, and each Windows NT process is restricted to 2 GB, you cannot increase the number of workthreads indefinitely. At some point, you have to start another AGate process. For further information, see Performance Limiting Factors. The default value for both these parameters is 40 (4 for a minimal configuration).
MaxWorkThreadStackSize	Maximum stack size (in bytes) available for each workthread. During ITS setup, this parameter is undefined and therefore not visible in ITS Administration. The default is assumed to be 2.5 MB. To change this value, you must set the following Windows NT registry value explicitly to a different value: \HKEY_LOCAL_MACHINE\SOFTWARE\SAP\its\2.0\ <ITS instance>\Programs\AGate\ MaxWorkThreadStackSize You then see the parameter in ITS Administration. The following main factors impact stack size: Recursive calls to HTML^Business functions Recursive calls can occur in any HTML template. In the SAPGUI for HTML, for example, they are used to generate tree controls. If a tree control is very deeply nested, this could result in a stack overflow. HTTP compression If you are using HTTP compression (that is, the value of the service parameter ~http_use_compression is set to 1), the compression algorithm uses stack space to store part of the compressed page. To avoid stack overflow with HTTP compression, you should set MaxWorkthreadStackSize to a value equal to or greater than the size of the largest HTML page that you expect to be generated + 1000000. Since this new setting inevitably affects the memory allocation of each workthread, you may have to adjust the value of MaxWorkThreads. The formula for calculating the total memory consumption of all the workthreads of an AGate process is: ( maxWorkthreads + 3 ) * ( MaxReqSize + MaxRespSize + MaxCtxtSize + MaxWorkThreadStackSize ) If the new value of MaxWorkthreadStackSize results in an unacceptably low number of workthreads per AGate process, you should switch off HTTP compression. In some cases, you can reduce the default maximum stack size. If, for example, you are not using the SAP GUI for HTML, you can reduce the stack size to as little as 1 MB.
RfcCompression	Enables / disables compression of RFC data between the ITS and the R/3 System. The RFC protocol is used to create complex user interface controls in the SAPGUI for HTML and to transfer raw data from the R/3 System to the ITS. During ITS setup, this parameter is undefined and therefore not visible in ITS Administration. The default is assumed to be 1 (compression of RFC data enabled). To disable compression of RFC data, you must set the following Windows NT registry value explicitly to 0: \HKEY_LOCAL_MACHINE\SOFTWARE\SAP\its\2.0\ <ITS instance>\Programs\AGate\RfcCompression You then see the parameter in ITS Administration.
StaticBor	Enables / disables caching of metadata retrieved through calls to remote-enabled function modules (RFCs) and Business APIs (BAPIs) from flow files used in applications based on ITS Flow Logic. In development systems where the RFCs and BAPIs called from flow files are modified frequently, you should set this parameter to 0 (caching disabled). This way, the ITS gets the metadata for each new session. In production systems where the RFCs and BAPIs called from flow files are static (that is, rarely modified), you should set this parameter to 1 (caching enabled). This way, the ITS gets the metadata once and uses it for all sessions, because the behavior described above for development systems is expensive in a production environment. If you are obliged to make changes to RFCs or BAPIs called from flow files when this parameter is set to 1 (caching enabled), you must restart the ITS to activate the changes. In Workplace installations, it is especially important to enable caching. The default value is 1.
StaticTemplates	Enables / disables HTML template and flow file caching. The ITS manages a cache of HTML templates and flow files. In development systems where HTML templates and flow files are modified frequently, you should set this parameter to 0 (caching disabled). This way, the ITS always checks whether a file has been modified since it was last written to the cache. If changes have been made, the ITS reloads the HTML template or flow file into the cache. In production systems where HTML templates and flow files are static (that is, rarely modified), you should set this parameter to 1 (caching enabled), because the behavior described above for development systems is expensive in a production environment. If you are obliged to modify HTML templates or flow files in a production system when this parameter is set to 1 (caching enabled), ITS Administration provides a utility for reloading cached files. The default value is 0.
TimeoutPercentage	Percentage of timeout granted to high-load sessions. When the maximum number of permitted sessions is reached, the ITS kills idle sessions in advance of their timeout limits. For example, if a service has a timeout limit of 20 minutes, and TimeoutPercentage is set to 75 (75%), the ITS could, in high load situations, terminate the session running this service after an idle time of only 15 minutes. The default value is 75 .

Prerequisites

You have started ITS Administration.

Procedure

Select an ITS instance and choose an AGate server hosted at the local machine.

Choose Configuration.

You see several functions in an expanded directory structure.

You set these parameters with either the Performance function or the Registry function.

Choose a function:

To change the parameter values of CacheInvalidateHour, CacheInvalidateMinute, CacheSize, IncAGates, MaxAGates, MaxSessions, MaxWorkThreads, MinAGates, MinWorkThreads, StaticTemplates, StaticBor and TimeoutPercentage, choose Performance

To change the parameter values of DiagCompression, MaxCtxtSize, MaxHrnpSize, MaxInetSessionCtxtSize, MaxReqSize, MaxRespSize, MaxRfcSize, MaxServiceContextSize, MaxSessionContextSize, MaxWorkThreadStackSize, MinCtxtSize, MinHrnpSize, MinReqSize, MinRespSize, MinRfcSize and RfcCompression, choose Registry ® Programs ® AGate

Set values for the parameters as described in the table above:

To change a parameter in ITS Administration, choose it and enter the new value below the current value.

Save your changes.

Result

ITS Administration updates the values in the Windows NT registry. To apply these changes, you must restart the ITS instance.