Performance Tuning Guide > Tuning the Siebel Application Object Manager for Performance > Best Practices for AOM Tuning >

Tuning AOM Components for CPU and Memory Utilization


This section provides background information and guidelines for tuning your AOM components, particularly for setting values for the parameters MaxTasks, MaxMTServers, and MinMTServers.

Settings for these parameters determine how well the system performs under specific user load and operations. Parameter settings provide a means of controlling the server capacity through the Siebel Server infrastructure, and directly impact the overall capacity for each server.

How you set the MaxTasks, MaxMTServers, and MinMTServers parameters is a direct function of the factors described in Performance Factors for AOM Deployments, which determine the true capacity of the server.

NOTE:  The art of tuning AOM components is to come up with the right parameter settings that allow the server machines to host the largest number of users (scalability) with minimal impact on user response time (performance).

About MaxTasks, MaxMTServers, and MinMTServers

The AOM parameters MaxTasks, MaxMTServers, and MinMTServers are described below. You configure these parameters using Siebel Server Manager, which is described in detail in Siebel Server Administration Guide.

For background information about multithreaded processes, threads, and related concepts, see AOM Infrastructure.

As more users log in, new tasks start to handle these sessions, and new multithreaded processes are started to support the additional tasks. The tasks and processes are added according to the AOM load-balancing behavior, up to the maximum number of tasks and maximum number of multithreaded processes. For details, see Effect of AOM Parameter Settings, below.

NOTE:  MaxTasks, MaxMTServers, and MinMTServers are generic parameters that apply to many different Siebel Server components. However, much of the behavior described in this chapter is unique to AOM components. For more information, refer to Siebel Server Administration Guide.

These parameters relate to one another in the following ways:

Effect of AOM Parameter Settings

This section illustrates how an AOM behaves given particular example settings for the MaxTasks, MaxMTServers, and MinMTServers parameters. More realistic examples may be found in Formulas for Calculating AOM Parameter Values.

For example, if MaxTasks = 500, and MaxMTServers = 5, then the ratio MaxTasks/MaxMTServers = 100. This means that, at most, 100 threads (tasks) can run in a multithreaded process on this AOM.

Typically, MinMTServers would be set the same as MaxMTServers. However, in this example, assume MinMTServers = 4. In this case, four multithreaded processes start by default, which can handle a total of 400 concurrent threads.

As users start the application on the server, the number of concurrent threads rises, and the following occurs:

If AOM loads fall back, as users log out or session timeouts are enforced, then threads are freed up. In some cases, a multithreaded process whose threads have completed may also time out and stop running (this can happen only when MaxMTServers is greater than MinMTServers).

Guidelines for Configuring AOM Parameters

This section provides formulas and guidelines for setting the MaxTasks, MaxMTServers, and MinMTServers parameters for your AOM components.

NOTE:  All elements in the two formulas shown in Formulas for Calculating AOM Parameter Values vary according to your deployment. The number of concurrent users an AOM can support will depend on factors such as the number of processors, session timeout settings, and the average think time.

Typically, the AOM is the only component using significant resources on the Siebel Server machine. If you run multiple server components, or run non-Siebel modules, then an AOM on this machine may support fewer concurrent threads.

Follow these general steps to determine how to set these parameter values:

Formulas for Calculating AOM Parameter Values

Use the formulas below for calculating parameter values for your AOM components:

As necessary, after making your initial calculations, round up MaxMTServers to the nearest integer, calculate the remainder (X) of MaxTasks/MaxMTServers, then increment MaxTasks by adding (MaxMTServers - X). You do this to make sure that the ratio of MaxTasks/MaxMTServers is an integer.

NOTE:  The figure of 100 in the MaxMTServers formula represents the ratio of concurrent tasks per multithreaded process. The value of 100 is a rule of thumb only. For details, see below.

Variables in the above formulas are described below:

Example Settings for AOM Parameters

Along with other factors such as think time, the calculation of MaxTasks, MaxMTServers, and MinMTServers depends on your assumptions for target_number_of_users, anon_browser_users, and anon_users, which are described above. Example settings follow for Siebel Call Center and Siebel eService.

Example Settings for Siebel Call Center

For Siebel Call Center, assume (for example) a think time of 30 seconds, and assume that target_number_of_users = 500. For this application, anon_browser_users is not a factor. Depending on your implementation, anon_users might be about 5% of target_number_of_users (or 25). Your preliminary parameter values would be:

MaxTasks = (500 + 25) = 525

MaxMTServers = (500 + 25)/100 = 525/100 = 5.25 = 6 (round up)

MinMTServers = MaxMTServers = 6

Adjust the value of MaxTasks. The variable X = the remainder of (525/6) = 3. Increment MaxTasks by (MaxMTServers - X): 525 + (6 - 3) = 525 + 3 = 528. Therefore, the final calculations for parameter values would be:

MaxTasks = 528

MaxMTServers = MinMTServers =6

Example Settings for Siebel eService

For Siebel eService, assume (for example) a think time of 30 seconds, and assume that target_number_of_users = 500. Depending on your implementation, anon_browser_users might be about 25% of target_number_of_users (or 125), and anon_users might be about 20% of target_number_of_users (or 100). Your preliminary parameter values would be:

MaxTasks = (500 + 125 + 100) = 725

MaxMTServers = (500 + 125)/100 = 6.25 = 7 (round up)

MinMTServers = MaxMTServers = 7

Adjust the value of MaxTasks. The variable X = the remainder of (725/7) = 4. Increment MaxTasks by (MaxMTServers - X): 725 + (7 - 4) = 725 + 3 = 728. Therefore, the final calculations for parameter values would be:

MaxTasks = 728

MaxMTServers = MinMTServers =7

Anonymous User Pool on Siebel Web Server Extension

Calculations for anonymous browser users and anonymous users are part of the formulas for setting MaxTasks, MaxMTServers, and MinMTServers. The significance of these figures relates specifically to settings on the Siebel Web Server Extension (SWSE) that define anonymous user pools for one or more applications.

The size of the anonymous user pool should be based on the number of customers performing anonymous browsing without logging in as a registered user, and on how many users log in concurrently and how long each login takes.

After performing your initial MaxTasks sizing, review the SWSE stats page to gauge the actual size of the anonymous user pool at one time, and adjust your MaxTasks setting as needed.

The AnonUserPool parameter, located in the eapps.cfg file in the SWSE installation, determines the maximum size of the anonymous user pool for all affected applications served by the Web server:

Previous examples assumed anon_users = 25 for Siebel Call Center, and anon_browser_users = 125 and anon_users = 100 for Siebel eService.

NOTE:  The anonymous user pool also includes guest users, which are users who are logged in on a guest basis. Guest users apply to standard interactivity applications only. Anonymous browser users and guest users are subject to different timeout settings, using the parameters AnonSessionTimeout and GuestSessionTimeout, located in the eapps.cfg file in the SWSE installation. Your sizing calculations for anonymous browser users should consider guest users and all applicable timeout values affecting anonymous browser and guest user sessions.

For more information about the stats page and about the eapps.cfg file parameters AnonUserPool, AnonSessionTimeout, and GuestSessionTimeout, refer to Siebel Server Installation Guide for the operating system you are using and Security Guide for Siebel eBusiness Applications.


 Performance Tuning Guide 
 Published: 24 October 2003