Oracle® Solaris Studio 12.4: Performance Analyzer

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Updated: January 2015

Call Stacks and Program Execution

A call stack is a series of program counter addresses (PCs) representing instructions from within the program. The first PC, called the leaf PC, is at the bottom of the stack, and is the address of the next instruction to be executed. The next PC is the address of the call to the function containing the leaf PC. The next PC is the address of the call to that function, and so forth, until the top of the stack is reached. Each such address is known as a return address. The process of recording a call stack involves obtaining the return addresses from the program stack and is referred to as unwinding the stack. For information on unwind failures, see Incomplete Stack Unwinds.

The leaf PC in a call stack is used to assign exclusive metrics from the performance data to the function in which that PC is located. Each PC on the stack, including the leaf PC, is used to assign inclusive metrics to the function in which it is located.

Most of the time, the PCs in the recorded call stack correspond in a natural way to functions as they appear in the source code of the program, and the Performance Analyzer’s reported metrics correspond directly to those functions. Sometimes, however, the actual execution of the program does not correspond to a simple intuitive model of how the program would execute, and the Performance Analyzer's reported metrics might be confusing. See Mapping Addresses to Program Structure for more information about such cases.