ref: 0a6bcc7b83d9b5fac12229cac57207b9dc91ba2f
dir: /sys/man/3/kprof/
.TH KPROF 3 .SH NAME kprof \- kernel profiling .SH SYNOPSIS .nf .B bind -a #K /dev .sp .B /dev/kpctl .B /dev/kpdata .fi .SH DESCRIPTION The .I 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. .PP The file .B 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 kernel was running. The rest each hold the number of total ticks the kernel spent at any one program counter, indexed by their offset from the minimum kernel text address. .PP The file .B kpctl controls profiling. Writing the string .B start to .B kpctl begins profiling; .B stop terminates it. The message .B startclr restarts profiling after zeroing the array of counts. .PP The program .I kprof (see .IR prof (1)) formats the data for presentation. .SH EXAMPLE The following .IR rc (1) script runs a test program while profiling the kernel and reports the results. .sp .EX bind -a '#K' /dev echo start > /dev/kpctl runtest echo stop > /dev/kpctl kprof /386/9pcdisk /dev/kpdata .EE .SH SOURCE .B /sys/src/9/port/devkprof.c .SH SEE ALSO .IR prof (1)