Performance Application Programming Interface
Encyclopedia
In computer science
, Performance Application Programming Interface (PAPI) is a portable interface
(in the form of a library) to hardware performance counters on modern microprocessor
s. It is being widely used to collect low level performance metrics (e.g. instruction counts, clock cycles, cache misses) of computer systems running UNIX
/Linux
operating system
s.
PAPI provides predefined high level hardware events summarized from popular processors and direct access to low level native events of one particular processor. Counter multiplexing
and overflow
handling are also supported.
Operating system
support for accessing hardware counters is needed to use PAPI. For example, a Linux/x86 kernel has to be patched with a performance monitoring counters driver (perfctr link) to support PAPI.
Computer science
Computer science or computing science is the study of the theoretical foundations of information and computation and of practical techniques for their implementation and application in computer systems...
, Performance Application Programming Interface (PAPI) is a portable interface
Application programming interface
An application programming interface is a source code based specification intended to be used as an interface by software components to communicate with each other...
(in the form of a library) to hardware performance counters on modern microprocessor
Microprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...
s. It is being widely used to collect low level performance metrics (e.g. instruction counts, clock cycles, cache misses) of computer systems running UNIX
Unix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
/Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
s.
PAPI provides predefined high level hardware events summarized from popular processors and direct access to low level native events of one particular processor. Counter multiplexing
Multiplexing
The multiplexed signal is transmitted over a communication channel, which may be a physical transmission medium. The multiplexing divides the capacity of the low-level communication channel into several higher-level logical channels, one for each message signal or data stream to be transferred...
and overflow
Arithmetic overflow
The term arithmetic overflow or simply overflow has the following meanings.# In a computer, the condition that occurs when a calculation produces a result that is greater in magnitude than that which a given register or storage location can store or represent.# In a computer, the amount by which a...
handling are also supported.
Operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
support for accessing hardware counters is needed to use PAPI. For example, a Linux/x86 kernel has to be patched with a performance monitoring counters driver (perfctr link) to support PAPI.