(libc.info.gz) Processor Time
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(libc.info.gz) Processor And CPU Time
21.3.2 Processor Time Inquiry
-----------------------------
The 'times' function returns information about a process' consumption of
processor time in a 'struct tms' object, in addition to the process' CPU
time. Time Basics. You should include the header file
'sys/times.h' to use this facility.
-- Data Type: struct tms
The 'tms' structure is used to return information about process
times. It contains at least the following members:
'clock_t tms_utime'
This is the total processor time the calling process has used
in executing the instructions of its program.
'clock_t tms_stime'
This is the processor time the system has used on behalf of
the calling process.
'clock_t tms_cutime'
This is the sum of the 'tms_utime' values and the 'tms_cutime'
values of all terminated child processes of the calling
process, whose status has been reported to the parent process
by 'wait' or 'waitpid'; see Process Completion. In
other words, it represents the total processor time used in
executing the instructions of all the terminated child
processes of the calling process, excluding child processes
which have not yet been reported by 'wait' or 'waitpid'.
'clock_t tms_cstime'
This is similar to 'tms_cutime', but represents the total
processor time system has used on behalf of all the terminated
child processes of the calling process.
All of the times are given in numbers of clock ticks. Unlike CPU
time, these are the actual amounts of time; not relative to any
event. Creating a Process.
-- Macro: int CLK_TCK
This is an obsolete name for the number of clock ticks per second.
Use 'sysconf (_SC_CLK_TCK)' instead.
-- Function: clock_t times (struct tms *BUFFER)
Preliminary: | MT-Safe | AS-Safe | AC-Safe | POSIX Safety
Concepts.
The 'times' function stores the processor time information for the
calling process in BUFFER.
The return value is the number of clock ticks since an arbitrary
point in the past, e.g. since system start-up. 'times' returns
'(clock_t)(-1)' to indicate failure.
*Portability Note:* The 'clock' function described in CPU
Time is specified by the ISO C standard. The 'times' function is a
feature of POSIX.1. On GNU systems, the CPU time is defined to be
equivalent to the sum of the 'tms_utime' and 'tms_stime' fields returned
by 'times'.
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