FEW CLOSE ENCOUNTERS WITH REAL WORLD PERFORMANCE ISSUES
FEW CLOSE ENCOUNTERS WITH REAL WORLD PERFORMANCE ISSUESIntroduction
This paper is to explore few interesting performance issues I have personally encountered and
resolved. This paper is primarily designed to show even these uncommon performance issues can be
resolved using common scientific techniques. This presentation introduces various approaches to the
performance analysis useful in resolving these performance issues.
1. High Kernel Mode CPU usage
Background:
There are many application instances each servicing a disjoint group of users. As per the design, any
application instance can be shutdown with no user impact and traffic will be automatically rerouted
to surviving instances (almost similar to RAC, implemented at application level).
Application design is such that one instance of the application is serving a disjoint set of users and
every application instance has a front-end application database. Users connect to these application
instances and most of the working set of data is contained within that application database.
Application instance, application database and the storage is considered one module. This module
can be instantiated to any UNIX server quickly, in case of, hardware failures.
It is a brilliant design eliminating site-wide failure. Also, it is very easy to move the users also from
one application instance, say #1, to another application instance, say #2, if needed. This satisfies near
100% uptime requirements of the application.
There is also central repository database, mostly used for authentication and static data. Figure 1
illustrates this application design.
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