KPROF(3)						     Library Functions Manual							  KPROF(3)

NAME

       kprof - kernel profiling

SYNOPSIS

       bind -a #T /dev

       /dev/kpctl
       /dev/kpdata

DESCRIPTION

       The kprof device provides simple profiling data for the operating system kernel.   The data accumulates by recording the program counter of
       the kernel at each `tick' of the system clock.

       The file kpdata holds the accumulated counts as 4-byte integers in big-endian byte order.  The size of the file depends on the size of ker-
       nel  text.   The first count holds the total number of clock ticks during profiling; the second the number of ticks that occurred while the
       kernel was running.  The rest each hold the number of ticks the kernel program counter was within the corresponding 8-byte range of  kernel
       text, starting from the base of kernel text.

       The  file kpctl controls profiling.  Writing the string start to kpctl begins profiling; stop terminates it.  The message startclr restarts
       profiling after zeroing the array of counts.

       The program kprof (see prof(1)) formats the data for presentation.

EXAMPLE

       The following rc(1) script runs a test program while profiling the kernel and reports the results.

	    bind -a '#T' /dev
	    echo start > /dev/kpctl
	    runtest
	    echo stop > /dev/kpctl
	    kprof /mips/9power /dev/kpdata

SOURCE

       /sys/src/9/port/devkprof.c

SEE ALSO

       prof(1)

																	  KPROF(3)