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
AUTHOR
Carl Staelin and Larry McVoy
Comments, suggestions, and bug reports are always welcome.