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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
       Microsystems 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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