term% cat index.txt KPROF(3) Library Functions Manual KPROF(3)
NAME
kprof - kernel profiling
SYNOPSIS
bind -a #K /dev
/dev/kpctl
/dev/kpdata
DESCRIPTION
The kprof device provides simple profiling data for the operating sys‐
tem 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 kernel
text. The first count holds the total number of clock ticks during
profiling; the second the number of ticks that occurred while the ker‐
nel 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 ker‐
nel and reports the results.
bind -a '#K' /dev
echo start > /dev/kpctl
runtest
echo stop > /dev/kpctl
kprof /386/9pcdisk /dev/kpdata
SOURCE
/sys/src/9/port/devkprof.c
SEE ALSO
prof(1)
KPROF(3)