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LAT_SYSCALL(8)			    LMBENCH			LAT_SYSCALL(8)

NAME
       lat_syscall - time simple entry into the operating system

SYNOPSIS
       lat_syscall  [ -P <parallelism> ] [ -W <warmups> ] [ -N <repetitions> ]
       null|read|write|stat|fstat|open [ file ]

DESCRIPTION
       null   measures how long it takes to do getppid().  We chose  getppid()
	      because  in  all	UNIX  variants	we are aware of, it requires a
	      round-trip to/from kernel space and  the	actual	work  required
	      inside the kernel is small and bounded.

       read   measures	how  long  it  takes  to read one byte from /dev/zero.
	      Note that some operating systems do not support /dev/zero.

       write  times how long it takes to write one byte to /dev/null.  This is
	      useful  as  a  lower bound cost on anything that has to interact
	      with the operating system.

       stat   measures how long it takes to  stat()  a	file  whose  inode  is
	      already cached.

       fstat  measures	how  long it takes to fstat() an open file whose inode
	      is already cached.

       open   measures how long it takes to open() and then close() a file.

OUTPUT
       Output format is

       Null syscall: 67 microseconds

ACKNOWLEDGEMENT
       Funding for the development of this tool was provided by Sun  Microsys‐
       tems Computer Corporation.

SEE ALSO
       lmbench(8).

AUTHOR
       Carl Staelin and Larry McVoy

       Comments, suggestions, and bug reports are always welcome.

(c)1994 Larry McVoy		    $Date$			LAT_SYSCALL(8)

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