Client/Server CPU Statistics view

The Client/Server CPU Statistics view ( Window > Show View > Other… > QNX System Profiler > Client/Server CPU Statistics ) tracks the amount of client/server time spent in the RUNNING state. In a message-passing system, it may be that a particular thread is consuming a large amount of CPU time, but that CPU time is being consumed based on requests from one or more clients. In these cases, in order to achieve a higher performance, the client requests on the server must be reduced (assuming that the server is identified as a bottleneck).

This panel provides a tabular display of threads that spend time in a RUNNING state (slightly different from pure CPU usage) and breaks down the display such that for each thread there is a summary of how much time it spent directly in the RUNNING state and how much RUNNING time it imposed on other threads in the system and the total of those two times.

Figure 1. The System Profiler's Client/Server CPU Statistics view.

You can expand the table, via the View menu, to show how much time the client imposed on various server threads. The imposed time is cumulative: if client A sends to server B, then until B replies to A, any time that B consumes is seen as imposed on time. If during that time B sends to server C, then server C is also billed time as imposed on by A. The rationale here is that B would not have engaged with server C were it not for the initial message from A.

By sorting by imposed time, it is possible to identify which clients are predominantly driving the system and which servers may be bottleneck points.