clocktest - A test program for posix clock interfaces

clocktest is a test program for clock access via the POSIX clock and timer
interface as defined in the POSIX standard and the Single Unix Specification
(on the web http://www.unix.org). clocktest allows to perform the following
tests on a Unix system:

- Discovery of available clocks
- Display of current clock values and clock precision
- Test if process clocks are supported
- Verification of process clock operation
- Test if thread clocks are supported
- Verification of thread clock operation
- Test timed generation of periodic and single shot signals
- Access to arbitrary nonstandard clocks (such as CLOCK_SGI_CYCLE)
- Test may be run directly through the kernel system call interface
  or via function calls through the system library
- Verification of POSIX compliant behavior of system library for
  CLOCK_PROCESS_CPUTIME_ID and CLOCK_THREAD_CPUTIME_ID (a known
  glibc deficiency)

Usage
-----

clocktest <option1> <option2> ... <test>

Available tests are

--scan	Perform a scan for available clocks. Test availability of process
	and thread clocks. Verify POSIX compliant behavior of CLOCK_*_CPUTIME_ID
	clocks if glibc interface is in use.

--timer	Perform a periodic timer test. By default the test is run on
	CLOCK_REALTIME with a period of 1234567ns and a count of 5 signals

--show	Show clock value and precision

--clock-status Clock status summary for standard clocks (also default if no
	test specified)

--process-clocks Tests the ability to retrieve process and thread clocks of
	other processes

--single-thread	Verify thread/process clock operation in a single process

--multi-thread	Verify thread/process clock operations using threads

Available options are:

--kernel	Use kernel interface for clock tests [default]
--glibc		Use glibc library for clock tests
--clock=N	Use the named or numbered clock for the test
--interval=N	Use the specified interval for the timer test
--count=N	Specify the number of interations for a periodic timer test.
		Specify count=1 for single shot mode
--busywait	Busywait instead of giving up the time slice. This increases
		the reaction time of the process receiving the signal.


Typical uses:

clocktest	Show default clocks and their resolutions

clocktest --clock=SGI_CYCLE --timer
		Test intervals generated by SGI SHub RTC interrupts

clocktest --glibc --scan
		Detect glibc limitations

clocktest --kernel --scan
		Show kernel time capabilities