Table of Contents
lat_syscall - time simple entry into the operating system
lat_syscall
[ -P <parallelism> ] [ -W <warmups> ] [ -N <repetitions> ] null|read|write|stat|fstat|open
[ file ]
- 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 CB/dev/zero. Note that some operating systems do not support
CB/dev/zero.
- write
- times how long it takes to write one byte to CB/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 format is
Null
syscall: 67 microseconds
Funding for the development of
this tool was provided by Sun Microsystems Computer Corporation.
lmbench(8)
.
Carl Staelin and Larry McVoy
Comments, suggestions, and bug reports
are always welcome.
Table of Contents