profil.2

UNIX v6源代码 这几乎是最经典的unix版本 unix操作系统设计和莱昂氏unix源代码分析都是用的该版

.th PROFIL II 5/15/74
.sh NAME
profil \*- execution time profile
.sh SYNOPSIS
(profil = 44.; not in assembler)
.br
.ft B
sys	profil; buff; bufsiz; offset; scale
.s3
profil(buff, bufsiz, offset, scale)
.br
char buff[ ];
.br
int bufsiz, offset, scale;
.ft R
.sh DESCRIPTION
.it Buff
points to an area of core whose length (in bytes) is given by
.it bufsiz.
After this call, the user's program counter (pc)
is examined each clock tick (60th second);
.it offset
is subtracted from it, and the result multiplied by
.it scale.
If the resulting number corresponds to a word
inside
.it buff,
that word is incremented.
.s3
The scale is interpreted as an unsigned,
fixed-point fraction with binary point at the
left: 177777(8) gives a 1-1 mapping of pc's to words
in
.it buff;
77777(8) maps each pair of instruction words
together.
2(8) maps all instructions onto the beginning of
.it buff
(producing a non-interrupting core clock).
.s3
Profiling is turned off by giving a
.it scale
of 0 or 1.
It is rendered
ineffective by giving a
.it bufsiz
of 0.
Profiling is also turned off when an
.it exec
is executed but remains on in child and parent both
after a
.it fork.
.sh "SEE ALSO"
monitor (III), prof (I)
.sh DIAGNOSTICS
\*-