basic block

A set of instructions with a single entry point, a single exit point, and no branches into or out of the set.


A record in an experiment.

caliper points

A caliper point is a point at which you wish to mark your program so that later you may display performance taken between the marks (caliper points) you have set. A caliper point may be set at a particular location in the source, after a particular time interval, or when a particular signal is received by your program. An implicit caliper point is always present at the start of execution of the process. A final caliper point is set when the process calls _exit. Caliper points are numbered so you can select them with displaying performance data.

call stack

A software stack of functions and routines that represent the state of the program at any time. The functions and routines are listed in the reverse order, from top to bottom, in which they were called. If function a is immediately below function b in the stack, then a was called by b. The function at the bottom of the stack is the one currently executing.

context switch

The act of saving the state of one process and replacing it with that of another when both processes time-share a single processor.


The number of times an event takes place during data gathering. For example, a count may be kept of the number of times a function executes.

CPU time

Process virtual time plus time spent when the system is running on behalf of the process, performing such tasks as executing a system call. This is the time returned in pcsamp and usertime experiments. It can be specified in an experiment by using the ut,30000,2 marching orders.

dynamic shared object (DSO)

An object file that is similar in structure to an executable program, but it has no main program.

exclusive time

The execution time of a given function but not of any functions called by that function. See inclusive time.

graduated instruction

As a performance enhancement, when an R10000 system comes to a point in the execution of a program at which either of two paths might be taken, it begins to execute both paths until it knows for sure which path is correct. Graduated instructions are those on the path it will eventually follow. Issued instructions are those on the path it does not follow.

inclusive time

The execution time both of a given function and of any functions called by that function. See exclusive time.

overflow interval

As used by the hardware counter experiments, it is the number at which a hardware counter exceeds a preset value. See the speedshop man page, dsc_hwc experiment.


Program counter. A register that contains the address of the instruction that is currently executing.

process virtual time

Time spent when a program is actually running. This does not include either 1) the time spent when the program is swapped out and waiting for a CPU or 2) the time when the operating system is in control, such as executing a system call for the program. The marching orders ut,30000,1 return process virtual time.


The runtime linker. This is invoked when a dynamic executable is run. It maps in shared objects used by the executable, resolves relocations as ld does at static link time, and allocates common, if required.

statistical data

Sampling. The results from this method of data gathering vary from run to run.

system time

The time the operating system spends performing services for a program, such as executing system calls and I/O.


Translation lookaside buffer. This is hardware used by the CPU to quickly translate a virtual address (such as the name of a variable) to a physical memory address.

TDT model

Target Description Table model. A CPU model used to calculate ideal time.

user time

The same as CPU time.

wall-clock time

Total time a program takes to execute, including the time it takes waiting for a CPU. This is real time, not computer time. The marching orders ut,30000,0 return wall-clock time.